Download Plant Biology 2008 Final Program Final program and abstracts of

PB 2008
Plant Biology 2008 Final Program
Final program and abstracts of symposia,
minisymposia, and poster presentations at
Plant Biology 2008
The 2008 Joint Annual Meeting of the
American Society of Plant Biologists
and the
Sociedad Mexicana De Bioquimica
Rama: Bioquimica y Biologia Molecular de Plantas
Siglo XXI Convention Center
Mérida, Mexico
Thursday, June 26 through Tuesday, July 1, 2008
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PB 2008
ASPB OFFICERS AND EXECUTIVE COMMITTEE
August 2008
President: C. Robertson McClung
President-elect: Sarah M. Assmann
Past President: Richard Amasino
Secretary: Danny J. Schnell
Treasurer: Mark R. Brodl
Elected Members: Steven C. Huber, Karen E. Koch, Alan M. Jones
Chair, Board of Trustees: Daniel R. Bush
Chair, Publications Committee: Sally A. Mackenzie
Chair, Women in Plant Biology Committee: Judy A. Brusslan
Chair, Minority Affairs Committee: MariaElena B. Zavala
Chair, Education Committee: Jane P. Ellis
Chair, Membership Committee: Mel Oliver
Chair, International Affairs Committee: Arun Goyal
Sectional Representatives
Midwestern: John Z. Kiss
Northeastern: Lawrence B. Smart
Southern: TBA
Mid-Atlantic: Robert P. Donaldson
Western: Anireddy S.N. Reddy
Executive Director: Crispin Taylor, ex officio
THE MEETING AND ABSTRACTS
The program for Plant Biology 2008 (Yucatan Siglo XXI Convention Center, Mérida, Mexico) was organized by the Plant Biology 2008
Program Committee:
Chair: Danny J. Schnell
Committee: Sarah M. Assmann, Nicholas C. Carpita, Judy Callis, Georg Jander, Janet Braam, Anireddy S.N. Reddy, Federico Sánchez
and Teresa Hernández Sotomayor
The call for abstracts for poster presentations and minisymposia was published in December 2007. The deadline for abstracts was April 4,
2008. All of the abstracts were received electronically via the web. All abstracts received on time were accepted, and the program was
arranged from those abstracts. A searchable online version of the abstracts has been available since May 2008 via
http://abstracts.aspb.org/pb2008/public/. This abstract supplement was produced from the electronic files submitted directly by the
authors (missing numbers represent withdrawn abstracts). The author of each abstract is responsible for the abstract‘s accuracy,
appearance, and content.
© 2008 American Society of Plant Biologists
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PB 2008
CONTENTS
Complete Daily Schedules .....................................................................................................1-17
Thursday, June 26 .........................................................................................................1
Friday, June 27...............................................................................................................3
Saturday, June 28........................................................................................................5-8
Sunday, June 29.........................................................................................................9-10
Monday, June 30......................................................................................................11-13
Tuesday, July 1........................................................................................................15-17
Special Events.....................................................................................................................19-22
Committee Meetings.................................................................................................................23
General Information............................................................................................................25–27
Bus Schedule and Event Transportation......................................................................................28
Event Floor Plans.................................................................................................................29-31
Exhibitors............................................................................................................................32-36
Exhibit and Poster Layout..........................................................................................................37
Going Green.............................................................................................................................38
Spanish Phrases.......................................................................................................................39
Symposia and Minisymposia.................................................................................................40-88
Poster Sessions.................................................................................................................89-277
Index of Authors with Abstract Number.............................................................................279-293
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PLANT BIOLOGY 2008 SPONSORS
We would like to recognize the following organizations for their support of
Plant Biology 2008. We appreciate your continued support and commitment to the
field of plant biology.
Corporate Sponsor
&
Maize Biology Symposium
Internet Café
Official Meeting Bags
Official Meeting Pens
European Science Workshop:
Opportunities for plant biologists
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PB 2008
Plant Biology 2008 Daily Schedule
THURSDAY, JUNE 26
Start Time
8:00 AM
End Time
6:00 PM
Event/Item
Executive Committee Meeting
Location
Fiesta Americana - Club Room
3:00 PM
6:00 PM
Registration open in Fiesta Americana for preregistered attendees only
Fiesta Americana – Mérida Room
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2
PB 2008
Plant Biology 2008 Daily Schedule
Start Time
7:00 AM
End Time
10:00 AM
8:00 AM
4:00 PM
Event/Item
Registration open in hotel for pre-registered
attendees only
Exhibitors move in
8:00 AM
12:00 PM
Plant Physiology Editorial Board Meeting
8:30 AM
10:00 AM
Education Committee Meeting
11:00 AM
12:30 PM
Education Foundation Board Meeting
12:00 PM
6:00 PM
1:30 PM
2:30 PM
Registration open in Convention Center for preregistered attendees and on-site registrants
Opening Address and Awards Ceremony
2:30 PM
3:50 PM
Symposium I - Opening Symposium
2:30 – S011: Samuel C. Zeeman: 2007 Charles Albert
Shull Awardee – What plants do in the dark: the
FRIDAY, JUNE 27
Location
Fiesta Americana – Mérida Room
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Fiesta Americana – Club Room
Fiesta Americana – Board Room Sala
De Cosejo
Fiesta Americana – Exec Cntr 1 & 2
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Salon
Mérida
Siglo XXI Convention Center – Salon
Mérida
conversion of transitory starch into sucrose in leaves
3:10 – S012: Sarah Hake: 2007 Stephen Hales Prize
Winner – A genetic approach to plant morphology
3:50 PM
4:30 PM
Coffee Break
4:30 PM
5:50 PM
7:00 PM
10:00 PM
Perspectives of Science Leaders
Luis R. Herrera-Estrella, Ph.D., professor of plant
engineering at the Center for Research and Advanced
Studies of the National Polytechnic Institute, Irapuato,
Mexico
Opening Reception
7:30 PM – Welcome by Governor
7:45 PM – Ballet
8:30 PM – Reception at Courtyard
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Salon
Mérida
José Peón Contreras Theatre
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4
PB 2008
Plant Biology 2008 Daily Schedule
SATURDAY, JUNE 28
Start Time
7:000 AM
End Time
8:00 AM
Event/Item
Ambassadors’ Club Breakfast
Location
Fiesta Americana – Exec Cntr 1 & 2
7:00 AM
8:00 AM
Minority Affairs Committee
Fiesta Americana – Board Room
8:00 AM
7:00 PM
Registration Open
8:00 AM
12:30 PM
Poster set up
8:00 AM
7:00 PM
Speaker Ready Room Open
8:30 AM
12:20 PM
Sponsored by Monsanto
Symposium II – Maize Biology – Organizers: Sarah
Hake and Jean Phillipe Vielle Calzada
8:30 – S021: John Jones – The origins and early dispersal
Siglo XXI Convention
Pasaje
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Mérida
Center – Gran
Center – Chichen
Center – Chichen
Center – Salon
of maize: The palynological and archeological evidence
9:10 – S022: Vicki Chandler – Epigenetic silencing across
generations
10:10 - Coffee Break
10:40 – S023: Erik Vollbrecht - The maize inflorescence:
development, domestication and insights into grass
evolution
11:30 – S024: Jean Phillipe Vielle Calzada – The Codifying
Genome of the Palomero Mexican landrace
12:30 PM
3:00 PM
12:30 PM
2:00 PM
Poster Session – Lunch
12-30 – 1:00 Undergraduate Poster Session
1:00 – 2:00 Even Numbered Poster Session
2:00 – 3:00 Odd Numbered Poster Session
Public Affairs Committee Meeting
12:30 PM
7:00 PM
Exhibit Hall and Posters Open
3:00 PM
4:40 PM
Minisymposium 1 – Education Outreach – Chair:
Jane Ellis
3:00 - M0101: Adán Colón-Carmona - An inquiry-based
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall Committee Room
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglo XXI Convention Center – Salon
Mérida
plant genomics course and workshop: Phenotype to gene
and back again
3:25 - M0102: Chris Cullis - Lost crops of Africa: Involving
undergraduates in their rediscovery and development
3:50 - M0103: Nancy Moreno - Web-based biology
teaching resources
4:15 - M0104: Burkhard Schulz/Michael Van Oosten -
Video podCasts as a teaching tool in Plant Physiology
laboratory courses
3:00 PM
4:40 PM
Minisymposium 2 – Organelle Biology and Protein
Trafficking – Chair: Marisa Otegui
3:00 - M0201: Sally Mackenzie - Non-AUG translation
Siglo XXI Convention Center - Salon
Valladolid
initiation in plant protein dual targeting
3:25 - M0202: Steven M. Smith - Defining the plant
peroxisome and modeling its function
3:50 - M0203: Danny J. Schnell - The role of the TOC-TIC
translocons in regulated preprotein targeting to plastids
4:15 - M0204: Marisa S. Otegui - The ESCRT related
CHMP1A and B proteins mediate the localization of the
auxin efflux carrier PIN1 at the plasma membrane and are
required for embryo development.
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Plant Biology 2008 Daily Schedule
Start Time
3:00 PM
End Time
4:40 PM
SATURDAY, JUNE 28 (continued)
Event/Item
Minisymposium 3 – Metabolism Trafficking – Chair:
Georg Jander
3:00 - M0301: Jennifer R. Watling - Hot plants: single
Location
Siglo XXI Convention Center – Salon
Izamal
Minisymposium 4 – Plant Pathogen Interactions –
Chair: Hong Gu Kang
3:00 - M0401: Jagger J.W. Harvey - Biogenesis and
Siglo XXI Convention Center – Salon
Progreso
Minisymposium 5 – Root Biology – Chair: Joseph G.
Dubrovsky
3:00 - M0501: Joseph G. Dubrovsky - Root system
Siglo XXI Convention Center – Salon
Ekbalam
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglo XXI Convention Center – Salon
Mérida
power source, hybrid or turbo-charged?
3:25 - M0302: Alberto A. Iglesisas - Understanding the
fate of trioses-phosphate in plant cells. A study on the
regulation of cytosolic glyceraldehyde-3-phosphate
dehydrogenases
3:50 - M0303: Mark A. Settles - Multiple non-redundant
roles for plastidic 6-phosphogluconate dehydrogenase in
maize
4:15 - M0304: Georg Jander - Reduced activity of
Arabidopsis thaliana HMT2, a methionine biosynthetic
enzyme, increases seed methionine content
3:00 PM
4:40 PM
function of plant viral small RNAs
3:25 - M0402: Xiaohang Wang - Functional
characterization of CLE peptides from a plant-parasitic
nematode, Globodera rostochiensis
3:50 - M0403: Wei Ma - Cyclic nucleotides act as an early
signal upstream from Ca2+ in plant innate immunity
4:15 - M0404: Hong Gu Kang - CRT1, an Arabidopsis
ATPase that interacts with diverse resistance proteins and
modulates disease resistance to turnip crinkle virus
3:00 PM
4:40 PM
formation: How lateral root initiation is related to the
number of cells between successive primordia
3:25 - M0502: Jose Efrain Ramirez Benite - Root transition
zone is the primary site of copper-induced oxidative stress
3:50 - M0503: Rosangela Sozzani - Radial Patterning in
the Arabidopsis root: Exploring for new SHR target genes
4:15 - M0504: Jianbo Shen - Auxin mediates patterning of
cluster root development induced by phosphorus
deficiency in Lupinus albus
4:40 PM
5:10 PM
Coffee Break in Exhibit Hall
5:10 PM
6:50 PM
Minority Affairs Symposium – Chair: Adán ColónCarmona
5:10 - M0601: Eleanore Wurtzel - Maize: A model cereal
crop for developing strategies to solve global vitamin A
deficiency
5:35 - M0602: Neftalí Ochoa Alejo - Chili pepper:
Biotechnology of a historically and culturally important
crop for Mexicans
6:00 – M0603: Elisa Leyva-Guerreo - Vacuolar expression
of linamarase in cassava roots increases root free amino
acids and leaf protein
6:25 - M0604: Alejandra Jaramillo - Piperales: Spices,
medicine and models
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PB 2008
Plant Biology 2008 Daily Schedule
Start Time
5:10 PM
End Time
6:50 PM
SATURDAY, JUNE 28 (continued)
Event/Item
Minisymposium 7 – Protein Modification and
Turnover – Chair: Shaul Yalovsky
5:10 – M0701: Miguel E. Vega Sanchez - The rice E3
Location
Siglo XXI Convention Center – Salon
Valladolid
Minisymposium 8 – Intracellular Signaling – Chair:
Alan Jones
5:10 - M0801: Peter Geigenberger - Acclimatory sensing
Siglo XXI Convention Center – Salon
Izamal
ligase SPL11 ubiquitinates SPIN1, an RNA/DNA binding
protein involved in negative control of flowering time
5:35 – M0702: Shaul Yalovsky - Signaling by type-I
ROP/RAC GTPases requires transient acylation and
consequential partitioning into lipid rafts
6:00 – M0703: Maria Ek-Ramos - Subcellular localization
dynamics of two cell death regulating protein kinases in
tomato
6:25 – M0704: Peter Geigenberger - Redox-regulation of
carbon storage in plants
5:10 PM
6:50 PM
of the carbon status
5:35 - M0802: Elena Baena-González - Arabidopsis KIN10
and KIN11 are central mediators of convergent
transcriptional responses in energy and stress signaling
6:00 - M0803: Su-May Yu - Distinct Hexokinases (HXKs)
Act as Positive or Negative Regulators in the Sugar
Signaling Pathway
6:25 - M0804: Alan Jones - Heterotrimeric G protein
coupled D-glucose Signaling in Arabidopsis
5:10 PM
6:50 PM
Minisymposium 9 – Peptide Signaling – Chair: David
Craik
5:10 - M0901: David Craik - Discovery and Applications of
Siglo XXI Convention Center – Salon
Progreso
Minisymposium 10 – Drought and Flooding Stress –
Chair: Alejandra Covarrubias
5:10 - M1001: Julia Bailey-Serres - Elucidation of the
Siglo XXI Convention Center – Salon
Ekbalam
Membership Committee Meeting
Intercontinental – Salon Independencia
the Cyclotides: Circular Knotted Plant Proteins
5:35 - M0902: Erik A. Schmetz - Specialist herbivore
evasion of plant defense elicitation: Engineered cATPC as
a strategy to recover cowpea (Vigna unguiculata)
recognition and defense against velvetbean caterpillars
(Anticarsia gemmatalis).
6:00 - M0903: Alisa Huffaker - PROPEP Family Regulation
of Pathogen Defense in Arabidopsis thaliana
6:25 - M0904: Renu Srivastava - Proteolytic processing of
a plant peptide hormone by a subtilase in Arabidopsis
5:10 PM
6:50 PM
acclimation response of Arabidopsis seedlings to low
oxygen stress from the cellular to whole-plant level
5:35 - M1002: Alejandra Covarrubias - Translational
regulation conferred by the 3‘ untranslated region of a
transcript encoding a late embryogenesis abundant
protein in response to water deficit
6:00 - M1003: Gabriel Iturriaga - Improvement of drought
tolerance and grain yield in common bean by
overexpressing trehalose-6-phosphate synthase in rhizobia
6:25 - M1004: Yong-Fei Wang - SLAC1 is required for
plant guard cell S-type anion channel function in stomatal
signalling
7:30 PM
9:00 PM
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Plant Biology 2008 Daily Schedule
8
Start Time
7:30 PM
End Time
9:30 PM
7:30 PM
9:30 PM
7:30 PM
10:00 PM
SATURDAY, JUNE 28 (continued)
Event/Item
Education Workshop - Evaluation, Assessment, and
Research in Life Science Education: What, How,
and Why? Erin Dolan will be leading the session on
behalf of the Education Committee. She will be joined by
Nancy Moreno (Baylor College of Medicine). Food and
beverages will be available for workshop registrants. This
event requires a pre-purchased ticket.
Digital Art Workshop I: Guidelines for Preparing
Digital Art — Beginner
Speaker: Michael Hepp of The Sheridan Group
PUI Networking Reception
This annual event serves as an opportunity to bring
people from PUIs together to network, share information
on strategies for teaching and research in plant biology,
and explore other opportunities. This event requires a
pre-purchased ticket.
Location
Intercontinental - Imperio
Intercontinental – Grand Salon II
Intercontinental – Grand Salon I
PB 2008
Plant Biology 2008 Daily Schedule
SUNDAY, JUNE 29
Start Time
8:00 AM
End Time
6:00 PM
Event/Item
Registration Open
8:00 AM
7:00 PM
Posters Open
8:00 AM
7:00 PM
Speaker Ready Room Open
8:30 AM
12:20 PM
Symposium III – Biology of Tomato and
Solanaceaous Species – Organizers: Lukas Mueller and
Lus (Stella) Barrero
8:30 – S031: Roland Schafleitner – A genomics approach
Location
Siglo XXI Convention
Pasaje
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Mérida
Center – Gran
Center – Chichen
Center – Chichen
Center – Salon
to identifying drought resistance traits of potato
9:10 – S032: Fernando Carrari – Development of rapid
strategies for testing of candidate Solanaceae QTLs
9:50 – Coffee Break
10:20 – S033: Luz Stella Barrero – Application of genomic
tools – case study: tomato - Solanaceae
11:00 – S034: Felipe Cruz-Garcia – Synthesis and transfer
to the stigmatic surface of NaStEP, a vacuolar Kunitz
protinase inhibitor homolog and its role in pollen rejection
in Nicotiana
11:40 – S035: Esther Van Der Knaap – Underlying
mechanisms of diversity in tomato fruit morphology
12:30 PM
3:00 PM
12:30 PM
5:00 PM
Poster Session – Lunch
1:00 – 2:00 – Odd Numbered Poster Session
2:00 – 3:00 – Even Numbered Poster Session
Exhibit Hall Open
12:30 PM
2:30 PM
International Affairs Committee Meeting
3:00 PM
6:10 PM
Symposium IV - Martin Gibbs Medal Symposium –
Organizer Richard A. Jorgensen
3:00 – S041: Sue Rhee - Discovering new enzymes by
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall- Committee Room
Siglo XXI Convention Center – Salon
Mérida
combining computational and metabolomic approaches in
Arabidopsis and translating metabolic network knowledge
from model to crop plants
3:40 - S042: Rodrigo Gutierrez – VirtualPlant: A software
platform to support Systems Biology research in the postgenomic era
4:20 – Coffee Break in Exhibit Hall
4:50 – S043: Eric Kramer – Models of auxin transport and
action: from Arabidopsis to Populus
5:30 – S044: Richard A. Jorgensen - The iPlant
Collaborative: A cyberinfrastructure-centered community
for a new plant biology
5:00 PM
6:00 PM
Exclusive Exhibitor Only Cocktail Reception
Intercontinental – Colonial
7:30 PM
8:30 PM
ASPB Fellows Reception
Fiesta Americana - Mérida
7:30 PM
8:30 PM
Fiesta Americana – Yucatan 3 & 4
7:30 PM
9:00 PM
7:30 PM
10:00 PM
7:30 PM
10:00 PM
7:30 PM
10:00 PM
Grantsmanship Workshop-Federal Grant Opportunities
and Grantsmanship: A session on federal plant research
and education programs to learn about new directions in
funding, new priorities within current programs, and how
to get these ideas into well-written, appealing proposals.
Minority Affairs Dinner and Sponsored Speaker:
David Burgess - Boston College - There is Water Flowing
Out of the Pipeline; Why Not Take a Drink? This event
requires a pre-purchased ticket.
Career Workshop I - Getting the Most out of the
Postdoc Experience. This event requires a pre-purchased
ticket.
Career Workshop II - How to Get and Keep a Job – in
Academia, Industry, or Government. This event requires
a pre-purchased ticket.
Euro Workshop - Opportunities for plant biologists
Sponsored by the European Delegation to the USA
Hyatt Regency 2,3, & 4
Fiesta Americana – Yucatan 1
Fiesta Americana – Yucatan 2
Hyatt Regency Chichen Itza
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Plant Biology 2008 Daily Schedule
10
Start Time
7:30 PM
End Time
10:00 PM
7:30 PM
10:00 PM
SUNDAY, JUNE 29 (continued)
Event/Item
TAIR Workshop - Arabidopsis genome annotation: How
TAIR can help you and how you can help us!
Speakers: Peifen Zhang, David Swarbreck, Donghui Li
Gramene and SGN Database Overview Workshop
Location
Hyatt Regency 1
Hyatt Regency Uxmal
PB 2008
Plant Biology 2008 Daily Schedule
MONDAY, JUNE 30
Start Time
7:00 AM
End Time
8:15 AM
Event/Item
Women in Plant Biology Committee Meeting
Location
Fiesta Americana – Board Room
8:00 AM
6:00 PM
Registration Open
8:00 AM
7:00 PM
Posters Open
8:00 AM
7:00 PM
Speaker Ready Room Open
8:30 AM
12:30 PM
Symposium V – Tropical Agriculture – Organizers:
Richard Sayre and Miguel A. Gómez-Lim
8:30 – S051: Richard Sayre – Biofortification of cassava to
Siglo XXI Convention
Pasaje
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Itza Exhibit Hall
Siglo XXI Convention
Mérida
Center – Gran
Center – Chichen
Center – Chichen
Center – Salon
alleviate malnutrition; the bicassava plus program
9:15 – S052: Miguel A. Gómez-Lim – Genetic
transformation of tropical plant species
10:00 – Coffee Break
10:30 – S053: Marcos Buckeridge – A novel alpha-
galactosidase from coffee is likely to control mannan fine
structure in developing seeds
11:15 – S054: Justin Maresh – Alkaloid biosynthesis in
Madagascar periwinkle (Catharanthus roseus)
12:30 PM
3:00 PM
12:30 PM
1:30 PM
Poster Session/Lunch
All Posters
New Member/Section Reception
12:30 PM
3:00 PM
Exhibit Hall Open
3:00 PM
7:00 PM
Exhibit Hall Breakdown
3:00 PM
4:40 PM
Minisymposium 11 – Jasmonate Signaling – Chair:
Gregg Howe
3:00 - M1101: Edward Farmer - Jasmonate signaling and
Siglo XXI Convention Center –
Itza Exhibit Hall
Siglo XXI Convention Center –
Itza Exhibit Hall – ASPB Booth
Siglo XXI Convention Center –
Itza Exhibit Hall
Siglo XXI Convention Center –
Itza Exhibit Hall
Siglo XXI Convention Center –
Mérida
Chichen
Chichen
Chichen
Chichen
Salon
attack-stimulated growth reprogramming
3:25 - M1102: John Browse - JAZ repressor p roteins
control jasmonate signaling
3:50 - M1103: Javier Narváez-Vásquez - Systemic wound
signaling in tomato leaves is cooperatively regulated by
multiple plant peptides
4:15 - M1104: Carlos L. Ballaré - Modulation of jasmonate
sensitivity by reflection signals. A phytochrome answer to
the dilemma of plants
3:00 PM
4:40 PM
Minisymposium 12 - Small Regulatory RNAs and
Chromatin Remodeling – Chair: Jose L. Reyes
3:00 - M1201: Federico Sánchez - MicroRNA167 familiy:
Siglo XXI Convention Center – Salon
Valladolid
Minisymposium 13 – Environmental Sensing and
Responses – Chiar: Elaine Tobin
3:00 - M1301: Javier Lopez - Overexpression of
Siglo XXI Convention Center – Salon
Izamal
new insights on the auxin metabolism regulation in
phaseolus vulgaris roots .
3:25 - M1202: Jose L. Reyes - Conserved and Novel
microRNAs in the legume phaseolus vulgaris in response
to ABA and drought
3:50 - M1203: Michael Axtel - Whole-transcriptome
identification of Arabidopsis microRNA targets
4:15 - M1204: Justin W. Walley - Stress induced
chromatin remodeling differentially regulates plant stress
signaling pathways
3:00 PM
4:40 PM
Arabidopsis CRY1 affects tomato growth, chlorophyll,
anthocyanin and lycopene contents in fruit
3:25 - M1302: Frank Harmon - Temperature entrainment
of the Arabidopsis circadian clock requires ELF3 activity
3:50 - M1303: Shen X. Lu - Testing time: Can a pulse of
proposed oscillator components shift rhythms in
Arabidopsis?
4:15 - M1304: Peter V. Minorsky - Infradian rhythms in
bean seed imbibition -- not the moon, the sun!
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Plant Biology 2008 Daily Schedule
Start Time
3:00 PM
End Time
4:40 PM
MONDAY, JUNE 30 (continued)
Event/Item
Minisymposium 14 - Tomato and Solanaceous
Species – Chair: Ilan Paran
3:00 - M1401: Greg Maloney - Branched-chain amino
Location
Siglo XXI Convention Center – Salon
Progreso
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Salon
Mérida
acid-derived flavor volatiles in tomato fruit
3:25 - M1402: Antonio J. Matas - Cell type specific gene
discovery in tomato fruit using laser capture
microdissection and pyrosequencing
3:50 - M1403: Hui Kang - Involvement of a MADS-box
gene, jointless, in multiple hormonal regulation of tomato
development
4:15 - M1404: Ilan Paran - Common and unique
regulation of sympodial shoot development in pepper and
tomato
4:40 PM
5:10 PM
Coffee Break
5:10 PM
6:50 PM
Minisymposium 15 – Plant - Herbivore Interactions
– Chair: Linda Walling
5:10 - M1501: Linda Walling - Leucine aminopeptidase: A
key regulator for insect defense
5:35 – Abstract 1502: Vijay Singh - Arabidopsis defense
against green peach aphid: role of plant lipids
6:00 – Abstract 1503: Holger Merker - Oldies but goldies:
NAC transcription factors and leucine aminopeptidase in
plant defense
6:25 – Abstract 1504: Gary W. Felton - Salivary Enzymes:
The First Line of Defense against Plant Defenses?
5:10 PM
6:50 PM
Minisymposium 16 – Genome Evolution and
Comparative Genomics –Chair: Doreen Ware
5:10 - M1601: Xiaofan Zhou - The relationship of gene
Siglo XXI Convention Center – Salon
Valladolid
Minisymposium 17 – Hormones – Chiar: Marta
Laskowski
5:10 - M1701: Xiaofeng Wang - Molecular mechanisms of
Siglo XXI Convention Center – Salon
Izamal
Minisymposium 18 – Plant Symbiont Interactions –
Chair: Carmen Quinto
5:10 - M1801: Luis Cardenas - Fast and transient
Siglo XXI Convention Center – Salon
Progreso
evolutionary pattern and function of eukaryotic gene
family
5:35 - M1602: Apurva Narechania - Toward a better
understanding of cereal genome evolution through
ensembl compara
6:00 - M1603: Nelson Avonce - The evolutionary history of
the plant trehalose biosynthesis genes.
6:25 - M1604: Raul Alverez-Venegas - The Highly Similar
Arabidopsis Homologs of Trithorax ATX1 and ATX2
Encode Divergent Bichemical Functions
5:10 PM
6:50 PM
receptor kinase activation, dimerization and
phosphorylation in brassinosteroid signal transduction
5:35 - M17092: Jeff Shen - The WRKY transcription factor
superfamily mediates plant responses to several hormones
6:00 - M1703: Georgiana Ponce - Interplay of ethylene
and gravitropic stimulation regulates the pattern of cell
differentiation in root cap cells of maize roots
6:25 - M1704: Marta Laskowski - Rhizotaxy is regulated by
polar auxin transport
5:10 PM
6:50 PM
intracellular ROS changes in living root hair cells
responding to specific NFs
5:35 - M1802: Julia Frugoli - Regulation of nodule number
in Medicago truncatula: sunn, lss, rdn and rae
6:00 - M1803: Quan Zhang - Positional cloning of STR, a
gene required for arbuscular mycorrhizal (AM) symbiosis
in Medicago truncatula
6:25 - M1804: Ranamalie Amarasinghe - Transporters
operating at the plant-fungal interface in tall fescueendophyte symbiotic association; Novel insights from a
nutritional stand point.
12
PB 2008
Plant Biology 2008 Daily Schedule
Start Time
7:30 PM
End Time
8:30 PM
7:30 PM
9:00 PM
7:30 PM
9:30 PM
7:30 PM
10:00 PM
MONDAY, JUNE 30 (continued)
Event/Item
USDA Reception
All employees of the U.S. Department of Agriculture are
invited to attend this annual reception. Enjoy the
opportunity to share a beverage and mingle with this
diverse group.
Women In Plant Biology Committee Sponsored
Speaker and Dinner - The Good Side of a Macho
Culture. Speaker: Patricia León. This event requires a
pre-purchased ticket.
Digital Art II – Guidelines for Preparing Digital Art —
Advanced. Speaker: Michael Hepp of The Sheridan Group
Plant Metabolic Network (PMN) & Sol Genomics
Network (SGN) & Gramene Metobolic Pathway
Databases Workshop
This workshop will present a number of metabolic
pathway databases: PlantCyc, MetaCyc, AraCyc, SolCyc
and RiceCyc. Speakers: Peifen Zhang, Lukas Mueller,
Chengzhi Liang
Location
Fiesta Americana – Celestun
Fiesta Americana – Yucatan 2,3 & 4
Fiesta Americana – Yucatan 1
Fiesta Americana - Mérida
13
14
PB 2008
Plant Biology 2008 Daily Schedule
TUESDAY, JULY 1
Start Time
8:00 AM
End Time
3:00 PM
Event/Item
Registration Open
Location
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall
Siglp XXI Convention Center – Chichen
Itza Exhibit Hall
Fiesta Americana - Club Room
8:00 AM
2:00 PM
8:00 AM
3:00 PM
Posters Open
Please remove your posters by 2 PM
Speaker Ready Room Open
8:00 AM
10:00 AM
Executive Committee Breakfast
8:30 AM
10:10 AM
Minisymposium 19 – Emerging Technologies –
Chair: Amit Dhingra
8:30 - M1901: Erich Kombrink - The yeast three-hybrid
Siglo XXI Convention Center – Salon
Mérida
Minisymposium 20 – Gene Regulation – Chair: JC
Jang
8:30 - M2001: Colleen Doherty - Identifying cold
Siglo XXI Convention Center – Salon
Valladolid
system: A screening platform for the identification of
targets of small signaling molecules
8:55 - M1902: Zhiyang Zhai - RNAi-in protoplasts as a
rapid, high-throughput procedure for targeted geneinactivation and functional analyses of Arabidopsis genes
9:20 - M1903: Mathew E. Hudson - Genomics of systemspecific model plants using next-generation sequencing
9:45 - M1904: Amit Dhingra - Enabling targeted
resequencing of arbitrarily long conserved DNA sequences
8:30 AM
10:10 AM
regulatory networks in Arabidopsis
8:55 – M2002: Kenzo Nakamura - Sugar-regulated gene
expression and the control of seed oil synthesis in
Arabidopsis
9:20 – M2003: David Skibbe - Mutator transposition alters
the transcriptome and proteome of developing maize
anthers
9:45 – M2004: J.C. Jang - P-bodies and ARE-mediated
post-transcriptome in plants
8:30 AM
10:10 AM
Minisymposium 21 – Seed Biology – Chair: Jeff Shen
8:30 - M2101: Woei-Jiun Guo - An ABA/stress-induced
Siglo XXI Convention Center – Salon
Izamal
Minisymposium 22 – Phytoremediation – Chair:
Sharon L. Doty
8:30 - M2201: Sharon L. Doty - Enhancing
Siglo XXI Convention Center – Salon
Progreso
HVA22 protein inhibits GA-induced programmed cell death
in aleurone cells
8:55 – M2102: Russell Johnson - The wheat PKABA1interacting factor TaABF1 mediates both abscisic acidsuppressed and abscisic acid-induced gene expression in
aleurone cells
9:20 - M2103: Ljudmilla Borisjuk - Functional analysis of
the plastidial glucose-6-phosphate/phosphate translocator
in legume seeds suggests a role for cellular differentiation
and storage control
9:45 – M2104: Daniel Vernon - Diverse impacts of PPR
knockout mutations on Arabidopsis embryo morphology,
cell organization, and plastid development
8:30 AM
10:10 AM
phytoremediation of a variety of organic pollutants
8:55 – M2202: Elizabeth Pilon-Smits - Plant selenium
hyperaccumulation functions as a defense against
herbivory
9:20 – M2203: Usha Balasundaram - A nucleo-cytoplasm
co-localized type 2 metallothionein from Prosopis juliflora
confers heavy metal tolerance to transgenic tobacco
9:45 – M2204: David G. Mendoza-Cozatl -
Characterization of the thiol-peptides in the phloem sap of
Brassica napus and their role in the long-distance
transport of cadmium
15
Plant Biology 2008 Daily Schedule
Start Time
8:30 AM
End Time
10:10 AM
TUESDAY, JULY 1 (continued)
Event/Item
Minisymposium 23 – Photosynthesis – Chair: John
Cushman
8:30 - M2301: Steven Rodermel - Suppressors of the var2
Location
Siglo XXI Convention Center – Salon
Ekbalam
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Salon
Mérida
variegation mutant of Arabidopsis provide access to
regulatory networks that govern chloroplast biogenesis
8:55 - M2301: Aleel K. Grennan - Role of pheophorbide a
oxygenase in chlorophyll degradation
9:20 - M2303: Ruey-hua Lee - Alkaline α-galactosidase
degrades thylakoid membranes in the chloroplast during
rice leaf senescence
9:45 - M2304: Katia Silvera - Crassulacean Acid
Metabolism in tropical orchids: Integrating isotopes,
habitat preference and gene expression
10:10 AM
10:40 AM
Coffee Break
10:40 AM
12:20 PM
Minisymposium 24 – Plant Biotechnology – Chair: Yi
Li
10:40 – P49002: Elsbeth Walker - TcJAMYC: a
transcriptional regulator of paclitaxel (TaxolTM)
biosynthesis in cultured Taxus cells
11:05 - M2402: Yi Li - Gene-deletor: A tool to eliminate all
transgenes in pollen and seed when their functions are no
longer needed or their presence can cause concerns
11:30 - M2403: Rima Menassa - Trafficking, degradation
and purification of recombinant IL-10 protein in plants
11:55 – P49005: Qungang Qi - Biochemical
characterization and mutational analysis of aspartate
kinases to identify feedback-resistant variants and seedspecific over-expression of the variants for enhanced
threonine levels in soybean seed
10:40 AM
12:20 PM
Minisymposium 25 – Cell to Cell and Long Distance
Signaling – Chair: Bernard Carroll
10:40 - M2501: Bernard Carroll – Genetic and molecular
Siglo XXI Convention Center – Salon
Valladolid
Minisymposium 26 – Reproductive Biology – Chair:
Heather Owen
10:40 - M2601: Dazhong Zhao - Signaling of anther cell
Siglo XXI Convention Center – Salon
Izamal
analysis of long-distance mRNA silencing in Arabidopsis
11:05 - M2502: Byung-Kook Ham - Molecular
characterization of phloem-mobile ribonucleoprotein
complexes
11:30 - M2503: Jeanmarie Verchot-Lubicz - Potato virus X
proteins induce ER-derived vesicles to enable
plasmodesmata transport and are targeted for
degradation by the 26S proteasome in plants
11:55 - M2504: Friedrich Kragler - A microtubuleassociated protein regulates the intercellular transport of
the non-cell-autonomous acting homeodomain proteins
10:40 AM
12:20 PM
fate determination by the TPD1 small protein and EMS1
receptor kinase in Arabidopsis
11:05 - M2602: Benjamin Rodriguez-Garay - The
occurrence and integrity of compound pollen in Agave
11:30 - M2603: Subbaiah Chalivendra - Protein-protein
interactions potentially governing pollen tube growth in
tomato (Solanum lycopersicum L.)
11:55 - M2604: Monica Alandete-Saez - Two plasma
membrane proteins expressed in the sperm cells and in
the egg cell of Arabidopsis play different roles during the
fertilization process
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PB 2008
Plant Biology 2008 Daily Schedule
Start Time
10:40 AM
End Time
12:20 PM
TUESDAY, JULY 1 (continued)
Event/Item
Minisymposium 27 – Mineral Nutrition – Chair:
Teresa Hernandez Sotomayor
10:40 - M2701: Uri Pick - A unique mechanism for Fe3+
Location
Siglo XXI Convention Center – Salon
Progreso
and Fe2+ acquisition in a halotolerant alga
11:05 - M2702: Jose Efrain Ramirez Benitez - Aluminium
induces changes in organic acids metabolism in Coffea
arabica suspension cells with differential Al tolerance
11:30 - M2703: Christopher M. Cohu - Reexamining the
role of superoxide dismutase in photosynthesis: Plants
without SOD activity in the chloroplast and cytosol
11:55 - M2704: Georgina Hernandez – Essential role of
MYB transcription factor: PvPHR1 in phosphate starvation
signaling in common bean (Phaseolus vulgaris)
10:40 AM
12:20 PM
Minisymposium 28 – Cellular Growth and Division –
Chair: William Thompson
10:40 - M2801: William Thompson - Analysis of DNA
Siglo XXI Convention Center – Salon
Ekbalam
1:30 PM
Lunch available for purchase
1:30 PM
Program Committee Meeting
1:30 PM
2:30 PM
ASPB Business Meeting
2:30 PM
6:20 PM
Symposium VI: President’s Symposium – Organizer:
C. Robertson McClung
2:30 – S061: C. Robertson McClung – Timing is everything
3:10 – S062: Edgar Spalding – Seeding establishment
Siglo XXI Convention Center – Gran
Pasaje
Siglo XXI Convention Center – Chichen
Itza Exhibit Hall – Committee Room
Siglo XXI Convention Center – Salon
Ekbalam
Siglo XXI Convention Center – Salon
Mérida
replication timing on Arabidopsis chromosome 4
11:05 - M2802: Luis Vidali - Class II formins are essential
for actin organization and tip growth
11:30 - M2803: Trino Ascencio-Ibanez - Geminivirus
infection alters expression of cell cycle genes to promote
endocycling in Arabidopsis
11:55 - M2804: Carmen Quinto - Silencing a receptor-like
kinase in Phaseolus vulgaris transgenic roots arrests
nodule development by impairing vascular bundle
formation
12:20 PM
12:30 PM
seen through the eyes of a computer
3:50 – Coffee Break
4:20 – S063: Steve Kay
5:00 – S064: Scott Poethig – Turning over a new leaf: The
regulation of vegetative phase changes in Arabidopsis
5:40 – Abstract S065: Johanna Schmitt – Arabidopsis in
the real world: Flowering time pathways in natural
environments across the species climate range
8:30 PM
Midnight
Final Party - Within a block from the hotels, stroll right
down the Paseo de Montejo to this lovely historic mansion
that is still owned by the original family. Enter through
the front gate and walk through the mansion to the back
garden for a lovely final reception with drinks and light
fare. Show off your salsa dancing to the live salsa band
or just enjoy the company and relax! A perfect ending to
our visit to this amazing city!
La Quinta Montes Molina
17
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PB 2008
SPECIAL EVENTS
FRIDAY, June 27
Opening Address & Awards Ceremony
1:30 – 2:30 pm at the Siglo XXI Convention Center – Salon Mérida
All attendees are invited to attend this prominent annual ceremony, which recognizes meritorious research and service in
plant biology by the presentation of awards to deserving individuals. Awards to be given this year are the ASPB-Pioneer HiBred International Graduate Student Prize, the Early Career Award, the Charles Albert Shull Award, the Charles Reid Barnes
Life Membership Award, the Corresponding Membership Award, the Fellow of ASPB Award, the Charles F. Kettering Award,
the Lawrence Bogorad Award for Excellence in Plant Biology Research, and the Stephen Hales Prize. The ceremony is
immediately followed by the ASPB Opening Symposium, which will feature the 2007 Charles Albert Shull Awardee, Samuel C.
Zeeman (ETH Zurich), and the 2007 Stephen Hales Prize Winner, Sarah Hake (USDA Plant Gene Expression Center, Albany).
Perspectives of Science Leaders
4:30 – 5:50 pm at the Siglo XXI Convention Center – Salon Mérida
Luis R. Herrera-Estrella, Ph.D., professor of plant genetic engineering at the Center for Research and Advanced Studies of
the National Polytechnic Institute, Irapuato, Mexico, will be the featured speaker. Luis will receive the 2008 ASPB
Leadership in Science Public Service Award during the program.
Plant Biology 2008 Opening Party
7:00 - 10:00 pm in the Jóse Peón Contreras Theatre
7:00 – Welcome by Governor
7:45 – Ballet
8:30 – Reception in courtyard one block away
SATURDAY, June 28
Poster Session and Lunch
12:30 – 3:00 pm in the Siglo XXI Convention Center – Chichen Itza Exhibit Hall
12:30 – 1:00 pm Undergraduate Poster Session
1:00 – 2:00 pm Even Poster Numbers
2:00 – 3:00 pm Odd Poster Numbers
Exhibit Hall and Posters Open
12:30 – 7:00 pm in the Siglo XXI Convention Center – Chichen Itza Exhibit Hall
Small Colleges/PUI Networking Reception
7:30 – 10:00 pm at the Intercontinental – Grand Salon I
This annual event serves as an opportunity to bring people from PUIs together to network, share information on strategies
for teaching and research in plant biology, and explore other opportunities. This event requires a pre-purchased ticket.
Education Workshop: Evaluation, Assessment, and Research in Life Science Education: What, How, and Why?
7:30 – 9:30 pm at the Intercontinental – Imperio
Whether you are broadening the impact of your research through educational activities or considering how to improve your
own teaching, evaluation will help you know when it works and help you learn when it does not. To assist scientists in
considering how to evaluate their educational efforts, including teaching and K-12 outreach, the ASPB Education Committee
is dedicating the Plant Biology 2008 Education Workshop to science education evaluation. The workshop session will start
with an introduction to evaluation and an explanation of how it differs from education research and assessment. Qualitative
and quantitative approaches to evaluation and assessment will be described. Conferees are invited to bring evaluation
questions, ideas, and challenges to discuss, as half of the session will be structured in a working group format. A variety of
resources useful for designing and implementing science education evaluation as well as mechanisms for garnering funding
and publishing results will also be presented. Erin Dolan will be leading the session on behalf of the Education Committee.
She will be joined by Nancy Moreno (Baylor College of Medicine). Food and beverages will be available for workshop
registrants.
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Guidelines for Preparing Digital Art — Beginner
7:30 – 9:30 pm at the Intercontinental - Grand Salon II
Speaker: Michael Hepp of The Sheridan Group
There are a lot of variables to consider when creating digital art. What software are you using? What size should the figure
be? In which format should it be saved? What color mode should be used? We can help you create publication-ready
figures from the beginning so that you won‘t have to spend time fixing problems later. If you‘ve never created digital
figures on your own, or you know only the basics, this is the best place to start. The interactive presentation will include live
demonstrations in Adobe Photoshop and Illustrator, along with material on how to prepare figures that will reproduce the
finest detail and most accurate color both online and in print. Topics will include color space, resolution, fonts, and file type.
The presenter will be Michael Hepp, Technology Strategist for The Sheridan Group, the company that produces Plant
Physiology and The Plant Cell. There will be ample time for Q & A at the end of the session.
SUNDAY, June 29
Poster Session and Lunch
12:30 – 3:00 pm in the Siglo XXI Convention Center - Chichen Itza Exhibit Hall
1:00 – 2:00 pm Odd Poster Numbers
2:00 – 3:00 pm Even Poster Numbers
Exhibit Hall Open
12:30 – 5:00 pm in the Siglo XXI Convention Center - Chichen Itza Exhibit Hall
Career Workshop I – Getting the Most out of the Postdoc Experience
7:30 – 10:00 pm at the Fiesta Americana - Yucatan 1
Panelists will discuss the range of postdoc options, what PIs are looking for in postdoc applicants, how to choose a mentor
and a project, and many other topics.
Career Workshop II – How to Get and Keep a Job – in Academia, Industry, or Government
7:30 - 10:00 pm at the Fiesta Americana - Yucatan 2
Networking strategies, negotiation skills, balancing job responsibilities, and writing effective application letters are among
the topics up for discussion.
Grantsmanship Workshop
7:30 - 8:30 pm at the Fiesta American - Yucata 3 & 4
Federal Grant Opportunities and Grantsmanship: A session on federal plant research and education programs to learn about
new directions in funding, new priorities within current programs, and how to get these good ideas into well-written,
appealing proposals. Both research- and education-centered opportunities will be explored.
Minority Affairs Committee Sponsored Speaker and Dinner
7:30 – 9:00 pm at the Hyatt Regency 2,3,4
Featuring David Burgess from Boston College who will speak on ―There is Water Flowing Out of the Pipeline; Why Not Take
a Drink?‖ This annual gathering is sponsored by the ASPB Committee on Minority Affairs for meeting attendees. This event
requires a pre-purchased ticket.
TAIR Workshop I: Introduction to TAIR
7:30 - 10:00 pm at the Hyatt Regency 1
Arabidopsis genome annotation: How TAIR can help you and how you can help us!
Speakers: Peifen Zhang, David Swarbreck, Donghui Li
The Arabidopsis Information Resource (TAIR; http:www.arabidopsis.org) is a web resource providing free access to a wide
array of biological data and tools for the model plant Arabidopsis thaliana. This workshop will include an introductory
overview of TAIR‘s features before giving more detailed information about TAIR‘s on-going efforts to annotate gene
structure and function. The general orientation will describe the content of the database and the resources linked from the
TAIR portal pages as well as demonstrating how to search mutant seed stocks based on phenotypes. In the Gene Structure
Annotation section, we will describe how Arabidopsis serves as an important resource and potential benchmark for the
annotation of other plant genomes. As such, a "gold standard" of gene structure annotation is demanded. We will describe
our progress in meeting this aim and give details of the recent TAIR8 genome release. We will also explain how we integrate
community data into TAIR and outline the resources available for viewing and accessing this data. The Gene Function
Annotation section will detail the challenging task of trying to extract information from over 2,000 papers published each
year on Arabidopsis genes. We will briefly describe the process of annotating from the literature using controlled
vocabularies, based on GO and PO terms, and then demonstrate how controlled vocabularies allow for standarization of
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PB 2008
annotation, assist in comparative genomics and can be used to classify large data sets. Finally, we will provide some
suggestions for preparing manuscripts that can be quickly and accurately curated and publicized through TAIR.
Gramene & SGN Database Overview Workshop
7:30 – 10:00 pm in the Hyatt Regency - Uxmal
Gramene is a major comparative genomics and genetic database for the plants with an emphasis on capturing genotypic
and phenotypic information from grasses and cross-species sequence comparisons. SGN is a major clade-oriented database
for the Solanaceae, including tomato, potato, pepper, eggplant and other species. In the first part of the workshop, the
different data modules of Gramene and their associated user-interface and tools will be presented. In the second half, the
respective features of SGN will be presented, including resources of the tomato genome sequencing project. The intended
audience for these workshops are people new to grass or Solanaceae genomics and people who have used these databases
in the past but desire to know more.
Sponsored by the European Delegation to the USA
European Science: Opportunities for Plant Biologists
7:30 – 10:00 pm at the Hyatt Regency – Chichen Itza
The symposium will present current trends in European Plant Science and discuss opportunities for Transatlantic
Cooperation.The program will include presentations by Laurent Bochereau, Head of Science, Technology and Education,
Delegation of the European Commission to the USA, on the Transatlantic Cooperation and ERA-LINK; Professor Wilhelm
Gruissem, Chairman of the European Plant Science Organisation, EPSO, Zürich, Switzerland, on Plant Science in Europe; and
Professor Dianna Bowles, Project Coordinator, University of York, U.K. will focus on an Example of Transatlantic Cooperation
in Bio-based products research: EPOBIO (http://www.epobio.net ).
A discussion will follow with Professor Sarah Hake, Center Director of the Plant Gene Expression Center and Adjunct
Professor at University of California, Berkeley, and Dr. Richard V. Greene, Program Manager for Energy Biosciences.
Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, U.S. Department of Energy. A
Questions/Answers period will conclude the workshop.
MONDAY, June 30
Posters Open
8:00 am – 7:00 pm in Siglo XXI Convention Center - Chichen Itza Exhibit Hall
12:30 – 3:00 Poster Session and Lunch
Exhibit Hall Open
12:30 – 3:00 pm in Siglo XXI Convention Center - Chichen Itza Exhibit Hall
New Members/Section Reception
12:30 – 1:30 pm in the ASPB Booth Siglo XXI Convention Center - Chichen Itza Exhibit Hall
A complimentary reception sponsored by ASPB Sections . All ASPB members are invited to attend the networking reception
where all sections of the society will be represented. Learn more about the sectional societies of ASPB and meet their
officers.
Women in Plant Biology Committee Sponsored Speaker and Dinner
7:30 – 9:00 pm at the Fiesta Americana - Yucatan 2, 3, & 4
Our speaker this year, Patricia León, from the Universiodad Nacional Autonoma de Mexico (UNAM) will speak on ―The Good
Side of a Macho Culture‖.
USDA Reception
7:30 - 8:30 pm at the Fiesta Americana - Celestun
All employees of the U.S. Department of Agriculture are invited to attend this annual reception. Enjoy the opportunity to
share a beverage and mingle with this diverse group.
Guidelines for Preparing Digital Art — Advanced
7:30 pm – 9:30 pm at the Fiesta Americana - Yucatan 1
Speaker: Michael Hepp of The Sheridan Group
If you are familiar with the basic concepts related to creating digital art, this session will cover more advanced topics such as
color management, using ICC profiles, working with MS Office documents and PDFs, and more. It will include live
demonstrations of advanced techniques for creating publication-ready figures. The presenter will be Michael Hepp,
21
Technology Strategist for The Sheridan Group, the company that produces Plant Physiology and The Plant Cell. There will be
ample time for Q & A at the end of the session.
Plant Metabolic Network (PMN) & Sol Genomics Network (SGN) & Gramene Metabolic Pathway Databases
Workshop
7:30 – 10:00 pm at the Fiesta Americana – Mérida
Speakers: Peifen Zhang, Lukas Mueller, Chengzhi Liang
This workshop will present a number of metabolic pathway databases: PlantCyc, MetaCyc, AraCyc, SolCyc and RiceCyc. The
Plant Metabolic Network (PMN) is a new freely accessible on-line resource of plant metabolic pathways. PMN is also a
platform for collaborative community curation of biochemical pathways, enzymes and genes. The PlantCyc database,
developed by PMN, comprehensively catalogs biochemical pathways across all plant species. This is the first database of its
kind, dedicated exclusively to plant research. The pathways in PlantCyc are manually curated from the literature. PMN also
has a full collection of plant species-specific databases developed by PMN and collaborators, Sol Genomics Network (SGN)
and Gramene among the others. The species-specific databases include AraCyc (Arabidopsis), RiceCyc (rice), LycoCyc
(tomato), MedicCyc (medicago), to name a few. They each map the full metabolic complement of an organism. MetaCyc is a
global reference database that also includes metabolism of prokaryotes and animals. This workshop will start with an
overview of unique and common features of each database, explanation of the process of pathway curation and methods of
assigning genes to pathways. We will then demonstrate how to query and retrieve the integrated information of pathways,
metabolites, enzymes and genes. We will also discuss applications using the resources such as displaying and analyzing
large scale microarray, proteomic or metabolic profiling data, studying comparative metabolism, and engaging in gene
discovery. Finally, we will outline how the user community can contribute to the ongoing improvement of the database
contents.
TUESDAY, July 1
Posters Open
8:00 am – 2:00 pm in Chichen Itza Exhibit Hall
Lunch available for purchase
12:20 – 1:30 pm in the Siglo XXI Convention Center - Gran Paseje
Final Party
8:30 - 11:00 pm at La Quinta Montes Molina
Within a block from the hotels, stroll right down the Paseo de Montejo to this lovely historic mansion that is still owned by
the original family. Enter through the front gate and walk through the mansion to the back garden for a lovely final
reception with drinks and light fare. Show off your salsa dancing to the live salsa band or just enjoy the company and relax!
A perfect ending to our visit to this amazing city! http://www.laquintamm.com/
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PB 2008
COMMITTEE MEETINGS
The following events are for ASPB Committee Members only unless otherwise noted. Learn more about the
committees and how you can participate at http://www.aspb.org/committees/
THURSDAY, June 26
ASPB Executive Committee Meeting
8:00 am – 6:00 pm Fiesta Americana - Club Room
FRIDAY, June 27
ASPB Education Committee
8:30 am – 10:00 pm Fiesta Americana - Board Room Sala De Cosejo
ASPB Education Foundation Board Meeting
11:30 am – 1:00 pm Fiesta Americana - Exec Cntr 1 &2
Plant Physiology Editorial Board Meeting
8:00 am – 12:00 pm Fiesta Americana - Club Room
SATURDAY, June 28
ASPB Minority Affairs Committee Meeting
7:00 am – 8:00 am Fiesta Americana - Board Room
ASPB Ambassador‘s Club Breakfast
7:00 am – 8:00 am Fiesta Americana - Exec Cntr 1 & 2
ASPB Public Affairs Committee Meeting
12:30 pm – 2:00 pm Siglo XXI Convention Center - Chichen Itza
Exhibit Hall Committee Room
ASPB Membership Committee Meeting
7:30 pm – 9:00 pm Intercontinental - Salon Independencia
SUNDAY, June 29
ASPB International Affairs Committee Meeting
12:30 pm – 2:30 pm Siglo XXI Convention Center - Chichen Itza
Exhibit Hall Committee Room
MONDAY, June 30
ASPB Women in Plant Biology Committee Meeting
7:00 am - 8:15 am Fiesta Americana - Board Room
TUESDAY, July 1
ASPB Executive Committee Meeting/Breakfast
8:00 am - 10:00 am Fiesta Americana - Club Room
ASPB Program Committee Meeting
ASPB Annual Business Meeting
*ALL ASPB MEMBERS WELCOME*
12:30 pm – 1:30 pm Siglo XXI Convention Center - Chichen Itza
Exhibit Hall Committee Room
1:30 pm - 2:30 pm in Siglo XXI Convention Center - Salon Ekbalam
23
24
PB 2008
GENERAL INFORMATION
Location of Events and Exhibits
Plant Biology 2008 major & mini symposia, posters, and exhibits will be held in the Siglo XXI Convention Center
Evening events and workshops will be held in the Fiesta Americana, Hyatt Regency, and the Intercontinental
hotels.
The opening reception will be held at the Jóse Peón Contreras Theatre and the final party will be held at La
Quinta Montes Molina.
Please refer to the daily schedule for locations of specific events. Buses will be provided to the Siglo XXI
Convention Center and the Jose Peon Contreras Theatre. Please refer to the bus schedule within this program.
Registration
The registration desk will be available for questions and registration during the hours below. Tickets for
available events may be purchased at the on-site registration desk, and t-shirts and abstract books/CDs will
have a separate pick-up area. The registration desk will be at the Fiesta Americana on Thursday afternoon and
Friday morning and then at the Siglo XXI Convention Center Gran Pasaje for the rest of the meeting.
Registration at Fiesta Americana in the Mérida Room – for pre-registered attendees only.
Thursday (June 26)
3:00 – 6:00 pm
Friday (June 27)
7:00 am – 10:00 am
Registration at the Siglo XXI Convention Center Gran Pasaje – for pre-registered attendees and on-site
registration.
Friday (June 27)
Saturday (June 28)
Sunday (June 29)
12:00 pm – 6:00 pm
8:00 am – 7:00 pm
8:00 am – 6:00 pm
Monday (June 30)
Tuesday July 1)
8:00 am – 6:00 pm
8:00 am – 3:00 pm
Housing
Any questions or problems concerning roommate matching will be handled by the housing agency, Hachero-Hill,
which will have a representative at the Registration Desk. Individual housing concerns should be addressed
with the respective hotel directly.
Badge Scanning
Attendee badges have RFID cards attached to them. The cards are on your badges to allow exhibitors to scan
your badge to contact you after the meeting if you‘d like them to. The RFID cards contain your name,
institution, email, and phone number and no additional information. Scanning requires direct contact to gather
the information on them. Attendees are welcome to not allow exhibitors to scan their badges if they so choose.
Exhibitors will receive a post-meeting mailing list that does not contain emails and phone numbers. Plant
Biology will honor any attendee who wishes to not be placed on the mailing list. Stop by the Registration Desk
if you have any questions.
Job Placement Center
The Job Placement Center posting area is located near the Registration Desk at the convention center.
Placement notices will be available for viewing during the conference. Placement Center procedures will be the
same as in prior years; information sheets will be available to employers and candidates at the Registration
Desk. Tables will also be available to conduct interviews on-site if the employer chooses to. Scheduling of
interviews is the responsibility of the employer and job seekers. Employers may pick up their position notices
and resumes during the last day of the meeting. Those not picked up will be mailed to the employers.
25
Internet Café
Plant Biology 2008 will feature an Internet Café in the Exhibit Hall. It will be open the same hours as the
posters. Please limit your online time to 10 minutes or less if others are waiting.
Cameras/Video/Audio Recording
Taking photos, video, or audio recording of any kind of the posters and sessions unless will be PROHIBITED
an author/speaker provides specific permission. This prohibition includes but is not limited to the use of camera
phones and any other digital recording devices.
Exhibits & Posters
Exhibits and posters are open during exhibit hours as listed on your schedule. Please refrain from entering
exhibits when they are closed. The posters will be organized by category. Exclusive poster session times are
listed in the schedule. Please attend your posters during the time slots based on your final poster number.
Poster abstracts will be available in the printed abstract book, CD or online. Late submissions are online only.
Speaker Ready Room
A place in the Chichen Itza Exhibit Hall will be available for PowerPoint presentation testing. Speakers should
test their presentations at least an hour prior to their presentation and be at their sessions at least 10 minutes
before they are scheduled to begin.
Message Board
Plant Biology 2008 will provide the traditional message boards near the Registration Desk at the convention
center for attendees to send and receive messages. An online message board is also available on the ASPB
website this year. Please do not use the Job Placement Service boards for messages.
Visiting the Yucatan – What to See and Do
If you would like assistance on touring please contact Amigo Yucatan, [email protected]. Mention that
you are attending ASPB‘s meetings in Mérida. They will work with you to create a specific tour or assist you in
joining a group. Confirmation on all tour arrangements will be from them not ASPB. Amigo Yucatan will also
have a representative available near the Registration Desk.
Getting Around Mérida
Please see the bus schedule and maps on the following pages.
Airport Transporation
Reserved Airport Transporation: Amigo Yucatan is pleased to offer transfers to and from your hotel.
Reserve online at http://www.yucatanbuyonline.com/aspb or visit the Amigo Yucatan representatives available
at registration or in the Hyatt Hotel Lobby. Mention that you are attending ASPB‘s meetings in Mérida.
Taxis
Taxis are available at the Mérida airport for transportation to the hotel. When exiting the airport, look for the
taxi booth to pre-purchase a taxi ticket to your hotel. Taxis will ask for the ticket and you will be on your way.
With the taxi ticket, you do not have any additional fare. If you like, you can tip the driver upon arrival.
Parking
Parking is available at all of the Plant Biology 2008 hotels. Check with the bellman at the front entrance upon
arrival at your hotel. The convention center has a large free parking lot beside it if you are driving or renting a
car.
Safety Notice
While enjoying the beautiful city of Mérida, please remember to keep your personal belongings secured.
Traveling in groups is a safe way to visit the many attractions of Mérida.
Plant Biology 2008 Smoking Policy
Smoking is not allowed at any Plant Biology 2008 annual meeting functions or areas.
26
PB 2008
Child Care
Through the Women in Plant Biology Committee, ASPB will provide a partial reimbursement for child care or
babysitting services for children under 12 years of age whose ASPB-member parents are attending Plant Biology
2008. Funds come from the bequest of Eli Romanoff, a long-time member of ASPP/ASPB and winner of the
Adolph E. Gude Award in 1995. This is a continuation of a program that was originally funded with a donation
from John Radin. The reimbursement is available to ASPB members on a sliding scale. Per family: Graduate
Students - up to $400; Post-docs - up to $300; and Faculty - up to $200
Parents should make their own arrangements via their hotel concierge, and then provide receipts to the Plant
Biology 2008 registration desk at the meeting or by fax to 301-251-6740. No claims will be honored if received
more than 60 days after the meeting closes. Reimbursements will be processed at ASPB headquarters
immediately following the meeting. ASPB assumes no responsibility with respect to child care services and
accepts no liabilities relative to the services.
Meeting Survey
A meeting survey will be e-mailed to attendees immediately following the meeting. Your response is considered
valuable by the society Program Committees. Thank you for your cooperation.
Additional Information/Questions
The conference Registration Desk will be able to assist you with any additional questions regarding the meeting.
27
BUS SCHEDULE & EVENT TRANSPORATION
The conference hotels are approximately 20 minutes away from the Siglo XXI Convention Center. Complimentary buses will
be provided for attendees at scheduled times.
PARKING: Free parking is available at the Siglo XXI Convention Center. Driving directions can be obtained from the
Registration Desk or the hotel concierge.
TAXIS: Taxis will be available at the hotels and the Convention Center for emergencies or if you need to depart at times
outside of the bus schedule below. Attendees are reponsible for their own taxi fees.
BUSES: Plant Biology 2008 will provide free buses for attendees on a scheduled basis from the hotels to the Siglo XXI
Convention Center. Below is a tentative schedule. PLEASE CHECK SIGNAGE IN YOUR HOTEL FOR EXACT TIMES.
Buses will depart every day during the meeting approximately 1 hour before the opening session at the Siglo XXI Convention
Center from the Hyatt Regency and Fiesta Americana Hotels. All hotels are within a walking distances from one another. If
you are not staying at these hotels please plan to arrive at the hotel 1 hour before the opening session of the day. Buses
will depart the convention center 10 minutes after the final session of the day.
For your convenience several buses will rotate to and from these locations throughout the day on an hourly basis. They will
pick-up at the Siglo XXI Convention Center and drop off at the Fiesta Americana and the Hyatt. You may also catch a bus
back to the Siglo XXI Convention Center during one of these hourly trips. PLEASE CHECK SIGNAGE IN YOUR HOTEL FOR
EXCACT TIMES.
TENTATIVE SCHEDULE – Check signage in your hotel for exact times.
June 27th, 2008
12:30 PM - Buses depart Fiesta Americana and Hyatt for the Siglo XXI Convention Center
HOURLY - Buses will run on an hourly basis back and forth from hotels to the Siglo XXI Convention Center
5:20 PM - Buses depart the Siglo XXI Convention Center for the hotels
6:45 p.m - Buses depart the hotels for the Jose Peon Contreras Theater
June 28th, 2008
7:30 AM - Buses depart Fiesta Americana and Hyatt for the Convention Center
HOURLY - Buses will run on an hourly basis back and forth from hotels to the Siglo XXI Convention Center
7:00 PM - Buses depart the Convention Center for the Fiesta Americana and Hyatt
June 29th, 2008
7:30 AM - Buses depart Fiesta Americana and Hyatt for the Convention Center
HOURLY - Buses will run on an hourly basis back and forth from hotels to the Siglo XXI Convention Center
6:20 PM - Buses depart the Convention Center for the Fiesta Americana and Hyatt
June 30th, 2008
7:30 AM - Buses depart Fiesta Americana and Hyatt for the Convention Center
HOURLY - Buses will run on an hourly basis back and forth from hotels to the Siglo XXI Convention Center
7:00 PM - Buses depart the Convention Center for the Fiesta Americana and Hyatt
July 1st, 2008
7:30 AM - Buses depart Fiesta Americana and Hyatt for the Convention Center
HOURLY - Buses will run on an hourly basis back and forth from hotels to the Siglo XXI Convention Center
6:30 PM - Buses depart the Convention Center for the Fiesta Americana and Hyatt
****FINAL PARTY at La Quinta Montes Molina IS WALKING DISTANCE FROM THE HOTELS (a block down the street Paseo
de Montejo) AND BEGINS AT 8:30 PM****
28
PB 2008
Siglo XXI Convention Center Floorplan
Fiesta Americana Floorplan
29
Hyatt Regency Floorplan
30
PB 2008
Intercontinental Floorplan
31
EXHIBITORS
American Society of Plant Biologists Booth 311
15501 Monona Drive
Rockville, MD 20855
Phone: 301-251-0560
www.aspb.org
Stop by the ASPB booth to learn about the many activities of our Society and meet the staff. Get the latest
information about ASPB publications including Plant Physiology and The Plant Cell, membership, education, Plant
Biology 2009, and public affairs.
ASPB Education Committee Booth 321
www.aspb.org/education
Throughout the meeting there will be exhibits and displays at the Education Booth. Winners of the Education Booth
competition sponsored by ASPB will be there to share their innovative strategies for education in plant biology. Dr.
Paul Williams will present his highly acclaimed Wisconsin Fast Plants exhibit. Free education materials will be
available: bookmarks, posters, flyers, and brochures.
Bio Chambers, Inc
Booth 303
477 Jarvis Avenue
Winnipeg, MB R2W 3A8
Canada
1-800-361-7778
www.BioChambers.com
Visit us at the BioChambers display to discuss your research requirements for plant growth chambers or growth
rooms. You can learn about our newest products and pick up literature or arrange for it to be sent to you.
CID, Inc Booth 322
4845 NW Camas Meadows Drive
Camas, WA 98607
360-833-8835
www.cid-inc.com
Innovators in field research methods for 18 years, CID designs and manufactures the world's most portable
instruments for Agricultural and Environmental Research, including Leaf Area Meters, Plant Canopy Imagers, Soil
Profile and Root Monitoring, Hand-Held Photosynthesis Systems and Spectrometers. Fast, light and portable, CID
instruments put data at your fingertips.
Conviron
Booth 102
590 Berry Street
Winnipeg, Manitoba
Canada R3H 0R9
204-786-6451
Toll free 800-363-6451
www.conviron.com
Conviron provides world-leading solutions in controlled environment systems. With products in 80+ countries,
Conviron is the world's largest supplier of plant growth chambers and rooms and high-fidelity greenhouses. Based in
Winnipeg, Canada, Conviron products also suit applications in pharmaceutical, nutraceutical, entomology research as
well as other life sciences disciplines.
Decagon Devices, Inc. Booth 310
2365 NE Hopkins Court
Pullman, WA 99163
Phone: 509-332-2756
www.decagon.com
Decagon Devices offers equipment to measure leaf wetness, PAR and stomatal conductance; as well as, monitoring
soil moisture and water potential. Decagon's Leaf Wetness Sensor determines canopy wetness, with no painting
required. The LP-80 measures real-time PAR and the Leaf Porometer allows you to measure stomatal conductance
without plant damage.
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PB 2008
Dynamax, Inc. Booth 217
10808 Fallstone #350
Houston, Texas 77099
281-564-5100
281-564-5200
www.dynamax.com
Dynamax, Inc. is a leading manufacturer of plant science research instrumentation, and is also the USA and Mexico
representative for ADC BioScientific and Delta-T Devices. Together we provide a wide range of products for plant
science, climate, soils, and environmental research. Please visit us at booth 217.
DOE/NSF/USDA
Booth 414, 416
www.nsf.org, www.csrees.usda.gov, www.er.doe.gov
Representatives from the Department of Energy, the National Research Initiative/US Department of Agriculture, and
the National Science Foundation will provide information about funding opportunities for plant biology research and
education.
Elsevier Booth 312, 314
360 Park Ave South
New York, NY 10010
Phone: 212-989-5800
www.elsevier.com
Elsevier is a leading publisher in Plant Science. New books include: Physiology of Woody Plants, Forest Ecosystems,
Soilless Culture, and more. Our innovative electronic products and services such as ScienceDirect and Scopus provide
cutting-edge online content for the needs of educators, researchers and students worldwide.
Environmental Growth Chambers Booth 202
510 East Washington Street
Chagrin Falls, OH 44122
www.egc.com
800-321-6854
Environmental Growth Chambers (EGC) has the largest selection of plant growth chambers of any company
worldwide. We also produce controlled environmental rooms, tissue culture chambers, lighted and refrigerated
biological incubators, shelf-lighted rooms, gas exchange chambers, hydroponics systems, Day-lit chambers, and Root
Zone cabinets. Please stop by and discuss your upcoming project requirements.
GenWay Biotech, Inc. Booth 302
6777 Nancy Ridge Drive
San Diego, CA 92121
Phone: (877) 4-GENWAY
or (858) 458-0866
www.genwaybio.com
GenWay, a leading protein, antibody and proteomic solutions provider, specializes in providing custom antibodies for
plant proteomic sample preparation columns. GenWay is known for its domain-specific IgY (chicken) antibody
technologies such as the IgY Rubisco removal column which can be used to effectively partition Rubisco protein from
plant proteomic samples.
The iPlant Collaborative
Booth 316
1657 E. Helen Street
Tucson, AZ 85721
www.iplantcollaborative.org
The iPlant Collaborative is a distributed, cyberinfrastructure-centered, international community of plant and computing
researchers enabling new conceptual advances through computational thinking and addressing an evolving array of
the most compelling grand challenges in the plant sciences and associated, cutting-edge research challenges in the
computing sciences.
33
Journal of Experimental Botany/Society for Experimental Biology
Booth 418
Bailrigg House
Lancaster University
Lancaster, LA1 4YE
United Kingdom
+44-1524-594690
www.jxb.oxfordjournals.org
Journal of Experimental Botany publishes high quality peer-reviewed plant science. Research papers from
corresponding authors whose institutions or departments have a full subscription to JXB are now published as OPEN
ACCESS papers and are freely available online to all immediately on publication. Please visit the JXB booth for more
information.
LI-COR Biosciences Booth 209, 211
4647 Superior Street
Lincoln, NE 68504
Phone: 402-467-3576
www.licor.com
LI-COR instruments for photosynthesis and fluorescence, gas analysis, leaf area and light measurement are
recognized worldwide for standard-setting innovation in plant science and environmental research. LI-COR pioneered
the development of infrared fluorescence labeling and detection systems for imaging, DNA sequencing,
microsatellites, and AFLPR for genomic research and discovery.
MO BIO Laboratories
Booth 326
2746 Loker Avenue West
Carlsbad, CA 92010
760-929-9911
www.mobio.com
MO BIO offers a complete line of nucleic acid extraction and purification kits from a variety of sample sources such as
plants, bacteria, plasmid, and others. Mini, Midi, Maxi and 96 well formats. Ask for more information on PowerCleanTM,
a secondary DNA clean up kit for challenging samples containing PCR inhibitors.
Monsanto Company Booth 410
800 North Lindbergh Boulevard
St. Louis, MO 63167
www.monsanto.com
636-737-6742
Monsanto, based in St. Louis, is a leading provider of agricultural products and integrated solutions for farmers. We
make Roundup(r), the world's best-selling herbicide, and other crop protection products. We produce leading seed
brands, including DEKALB(r) and Asgrow(r), and we provide our seed partners with biotechnology traits for insect
protection and herbicide tolerance. With our unique combination of products and our unparalleled resources in plant
biotechnology, we create integrated solutions that bring products and technologies together to improve productivity
and to reduce the costs of farming. Our Animal Agriculture unit provides enhanced swine genetics and products that
improve dairy production (Posilac(r)). Monsanto offers a broad range of challenging positions in the following areas:
Biotechnology and Genomics, Chemistry, Crop Analytics, Breeding, Breeding Technology, Regulatory Science and
Affairs, and Strategy and Operations.
Percival Scientific, Inc.
Booth 318
505 Research Drive
Perry, IA 50220
Phone: 515-465-9363
or (800) 695-2743
www.percival-scientific.com
Percival Scientific continues to set the standard of excellence for the environmental control industry and occupies over
60,000 sq. ft. of manufacturing space dedicated to the production of over 50 different models of plant growth
chambers, biological incubators and special application chambers to meet specific customer needs.
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PB 2008
Photon System Instruments Ltd.
Booth 206
Kolackova 39
61200 Brno
Czech Republic
+420-541-269-004
www.psi.cz
For over 12 years, we have specialized in the design and manufacture of custom-made, high quality instrumentation
for research in biological sciences. Our current product lines cover a wide range of instrumentation for: chlorophyll
fluorescence techniques, advanced imaging, high-tech bioreactors, and closed greenhouses (LED`s phytotrons).
PP Systems Booth 305
110 Haverhill Road
Suite 301
Amesbury, MA 01913
www.ppsystems.com
978-834-0505
978-834-0545 fax
See the latest high quality research instrumentation for measurement of photosynthesis, chlorophyll fluorescence, soil
respiration, CO2 & H2O infrared gas analysis, oxygen and vegetation reflectance along with a wide range of light
sensors (UVA/UVB, PAR, Red/Far Red). We are also the proud exclusive distributor for Hansatech Instruments, Gill
Instruments and Skye Instruments.
Qubit Systems, Inc.
Booth 204
4000 Bath Road
2nd Floor
Kingston, Ontario
Canada, K0H1S0
613-384-1977
www.qubitsystems.com
Instrumentation for plant and soil biology from low cost equipment for the teaching lab to the world‘s most
sophisticated chlorophyll fluorescence imaging systems. Our gas analyzers include the S104 Differential Oxygen
Analyzer capable or resolving +/- 1 ppm O2 against air, and extending the boundaries of open flow gas analysis.
The Samuel Roberts Noble Foundation, Inc.
Booth 225
PO Box 2180
Ardmore, OK 73402
580-223-5810
www.noble.org
[email protected]
The Samuel Roberts Noble Foundation, headquartered in Ardmore, Okla., is an independent, nonprofit institute
conducting plant science research and agricultural programs to enhance agricultural productivity, which influences
agriculture regionally, nationally and internationally. Founded in 1945, the Noble Foundation now has 378 employees,
representing more than 29 countries.
SoftGenetics, LLC.
Booth 221
200 Innovation Blvd., Suite 235
State College, PA 16803
814-237-9340
www.softgenetics.com
SoftGenetics features its ―Biologist Friendly‖ GeneMarker fragment analysis software with special application modules
for AFLP, T-RFLP, MicroSatellite: Mutation Surveyor sequence analysis software, and JelMarker Image Reading and
conversion software for Tilling, SNP Discovery and Ecotilling. Free trials are available for in-lab testing.
35
SPEX SamplePrep LLC Booth 301
203 Norcross Avenue
Metuchen NJ, 08840
Phone: 800-522-7739
www.spexcsp.com
The 2000 Geno/Grinder®, a high-throughput tissue lyser, and the Freezer/Mill®, a low throughput cryogenic mill
used with liquid nitrogen, are both specifically designed for extracting nucleic acids from plant tissues while preserving
the sample‘s integrity. Both mills disrupt the cell wall while increasing the surface area of the tissue.
Springer
Booth 213, 215
233 Spring Street
New York, NY 10013-1578
212-460-1501
www.springer.com
Springer is a major publisher in Life Sciences. Please stop by our booth to explore new book publications in Plant
Sciences offered at a conference discount and take a closer look at our journals. Staff will be on hand to answer any
questions you might have about publishing with Springer.
Taylor & Francis Group Booth 304, 306
2 Park Square
Milton Park
Abingdon
Oxfordshire
OX14 4RN, United Kingdom
Phone: +44 207 017 6001
www.informaworld.com
Garland Science/Taylor & Francis is pleased to exhibit Plant Biochemistry, by Bowsher, Steer and Tobin, and Molecular
Biology of the Cell by Alberts et al. Please visit our booth (#304) and browse through our publications, and learn
about our new forthcoming textbook Plant Biology, by Smith et al.
Wiley-Blackwell Booth 201, 203, 205
350 Main Street
Malden, MA 02148
Phone: 781-388-8361
www.wiley-blackwell.com
John Wiley & Sons is a global publisher of print and electronic products. In early 2007 Wiley acquired Blackwell
Publishing Ltd., considered to be among the very best publishers in the industry at building and maintaining
relationships with professional and scholarly societies. For more information, please visit www.wiley.com,
www.blackwellpublishing.com
Yucatan Store Booth 422, 424, 426
Local vendors from within Merida will sell authentic Yucatan items. Stop by and browse for souveniers to take home
and support the local economy.
36
PB 2008
EXHIBIT AND POSTER LAYOUT
37
GOING GREEN!
This year ASPB is making every effort to ensure that our 2008 meetings are as
environmentally friendly as possible. Plant Biology 2008 and The Pan American
Congress on Plants and BioEnergy will both be held in Mérida, Mexico. While the
unique location does present a few challenges in holding an entirely green meeting,
we hope the steps we are taking this year will increase awareness of the carbon
footprint created by our meetings.
Logistical steps for greening our 2008 meetings
Printing
Materials printed for the meetings were mostly produced in Mérida to avoid shipping and to provide income for
the local economy. Whenever possible, printing was done with natural or recycled materials.
Shipping
We cut our shipping weight in half this year by leaving behind our large ASPB booth and eliminating many other
materials. We encouraged our exhibitors to do the same. We‘ve made sure to ship only what will be used to
minimize waste and the necessity to ship back to the U.S.
Local Food and Supplies
We will serve mostly local food at all food events during the meetings. Materials, logistical items, and hired staff
are all sourced out to local vendors in Mérida.
Recycling
Recycling bins will be provided throughout the meeting space, and we have requested participating hotels to
provide recycling and linen and towel reuse programs in the hotel rooms.
Name Badge
Name badge collection bins will be provided at the end of the meeting so that badges can be reused for future
meetings.
Paperless
As in previous years, registration, housing and abstract submission forms were all online. ASPB has eliminated
the mailing of meeting flyers and instead is using electronic marketing methods. We are taking steps to
minimize waste on site.
Save Energy
As is customary in the Yucatan, we will conserve energy in meeting rooms that are not in use.
What can you do as an attendee?
1. Make a conscious effort to recycle, not only while in the meeting venues but also while touring or
2.
3.
4.
5.
38
enjoying the local area.
Take advantage of the linen and towel reuse program in the hotel rooms.
Be conscious of your water consumption by turning off the faucet while brushing your teeth and limiting
your shower. Use the water bottles provided at the meeting rather than purchasing water bottles.
Patronize the local shops and vendors.
Reduce your annual air travel, and make the ASPB meeting a high priority in the future!
PB 2008
Spanish Phrases
If you don‘t speak any Spanish at all, don‘t worry. Many people who work in the
tourist industry in Mexico speak English. However, any effort on your part to speak
Spanish will go a long way toward creating rapport between you and the Mexicans
you meet. You don‘t have to take an intensive course—these few phrases will
communicate the most important things you need to say.
Hola
Hello
Mexicans tend to be quite formal when it comes to greetings. A simple hola is fine
among friends, but in other situations, you should change the form you use
depending on the time of day:
Before noon: buenos días (good morning, good day)
From noon until dark: buenas tardes (good afternoon)
Gracias
Thank you
It‘s always polite to thank people who are providing you with a service—and even better to say it in their
language. The correct response is de nada. You should also learn to say please: por favor.
¿Cuanto cuesta?
How much is it?
Of course, if you hope to understand the answer, you‘ll need to know the numbers in Spanish. In a restaurant,
when you are ready to pay, ask for la cuenta.
There‘s a website that lists how to count from 1 to 100, and when you click on the number, you get the correct
pronunciation: www.donquijote.org/spanishlanguage/numbers/numbers1.asp.
¿Donde está . . . ?
Where is . . . ?
Knowing how to ask where things are can come in handy in many circumstances. If you‘re lucky, the person
answering you will point the way, so it won‘t matter if you don‘t understand the reply!
Me llamo . . .
My name is . . .
The best way to learn Spanish is to talk with people, and the way to begin is by introducing yourself.
Disculpe
Excuse me
There are different ways to say this, depending on the situation, but this one works in most situations—if you‘re
trying to get by someone and want them to move out of your way, if you‘ve made a faux pas, or if you‘re trying
to get someone‘s attention.
¿Puedo tomar una foto?
May I take a photo?
Some people don‘t like to have their picture taken, so to avoid conflicts, it‘s better to ask first.
No hablo español. ¿Habla usted inglés?
I don’t speak Spanish. Do you speak English?
Use as a last resort!
39
SYMPOSIA – FRIDAY JUNE 27
Date
Start
End
Symposium
Location
FRIDAY
June 27
2:30 PM
3:50 PM
Opening Symposium I
Siglo XXI Convention Center 2:30 - S011 - 2007 Charles Albert Shull Awardee: Samuel C.
Salon Mérida
Zeeman, ETH Zurich, Switzerland - What plants do in the dark:
The conversion of transitory starch into sucrose in leaves
3:10 - S012 - 2007 Stephen Hales Prize Winner: Sarah Hake,
Plant Gene Expression Center -
A genetic approach to plant morphology
S011 What plants do in the dark: The conversion of transitory starch into sucrose in leaves.
Zeeman, Samuel C.-presenter [email protected](a)
http://www.pbc.ethz.ch
Starch is a primary product of photosynthesis in leaves. In most plants, a large fraction of the photo-assimilated carbon is stored transiently
in chloroplasts as starch for use during the subsequent night. Starch is composed primarily of branched glucans (amylopectin) with an
architecture that allows the formation of insoluble, semi-crystalline granules. Recently, functional genomic studies in Arabidopsis and other
species have advanced our understanding of leaf starch breakdown. Our data suggest that starch is hydrolysed to maltose and glucose via a
pathway that requires recently-discovered proteins in addition to well-known glucan hydrolases (amylases). Discoveries made in the last
decade show that transient glucan phosphorylation is required for starch degradation. Amylopectin is phosphorylated by a class of glucan
dikinases. The phosphate groups probably serve to disrupt the semi-crystalline packing of the granule and thereby facilitate hydrolysis.
Multiple isoforms of β-amylase and debranching enzyme (isoamylase and limit dextrinase) then act in concert with disproportionating
enzyme to degrade the granule and oligosaccharide intermediates yielding predominantly maltose and some glucose. Surprisingly, some
well characterised enzymes such as α-amylase and α-glucan phosphorylase appear to have only minor or specialised roles. Maltose and
glucose are exported from the chloroplast on distinct transporters and metabolised in the cytosol to support sucrose synthesis, respiration
and growth.
(a) ETH Zurich
S012 A genetic approach to plant morphology
Hake, Sarah-presenter [email protected](a,b)
Chuck, George (a)
Candela-Anton, Hector (a)
Bolduc, Nathalie
(a,b)
Moon, Jihyun (b)
O'Connor, Devin (b)
Lunde, China (b)
Thompson, Beth (b)
The enormous variation in plant architecture arises from activities of meristems, the unassuming groups of cells that work in coordination to
maintain their totipotent nature while at the same time producing the precursor cells destined for more visible activities. Shoot meristems
initiate leaves and between the leaf and the main shoot reside the axillary meristems. Together the shoot apical meristem and axillary
meristems define the architecture of the plant, responsible for the pattern of leaf initiation, the size of the leaf, the polarity of the leaf and
the fate of axillary meristems. Our group has an ever-growing genetic tool-box to begin to understand plant organogenesis. We have taken
advantage of the sequenced grass genomes to positionally clone genes in maize that are defined by their mutant phenotype. Both the tassel
and the leaf have been excellent drawing boards to discover variation. The tassel has a genetically defined branching pattern that is easily
altered by natural variation and mutation. Similarly, the leaf has defined cell types in the proximal/distal and abaxial/adaxial axis that are
quickly scored. As each new gene is isolated, it becomes a tool in the analysis of other phenotypes, slowly building a network of how a plant
is put together.
(a) Plant Gene Expression Center, USDA-ARS (b) Plant and Microbial Biology Department, UC Berkeley
40
PB 2008
SYMPOSIA – SATURDAY JUNE 28
Date
SATURDAY
June 28
Start
8:30 AM
End
12:20 PM
Symposium
Sponsored by
Symposium II - Maize Biology - Organizers: Sarah Hake
and Jean Phillipe Vielle Calzada
8:30- S021 - John Jones - The origins and early dispersal of
Location
Siglo XXI Convention Center Salon Mérida
Maize: The palynological and archaeological evidence
9:10- S022 - Vicki Chandler - Epigenetic silencing across
generations
10:10 Coffee Break
10:40 - S023 - Erik Vollbrecht - The maize inflorescence:
Development, domestication and insights into grass evolutio
11:30 - S024 - Jean Phillipe Vielle Calzada - The Codifying
Genome of the Palomero Mexican landrace
S021 The origins and early dispersal of Maize: The palynological and archaeological evidence
Jones, John G.-presenter [email protected](a)
Pohl, Mary (b)
Pope, Kevin (c)
The path leading to the domestication of maize is shrouded in obscurity. Multiple lines of archaeobotanical evidence, including pollen,
starch, phytoliths and macrofossil remains are beginning to paint a picture of the origins and spread of what is arguably the world‘s most
important cultigen. Recent findings in archaeological excavations in both the lowlands and highlands of Mexico, Guatemala and Belize are
hinting at multiple lines of domestication. Placed into archaeological contexts, we see a complex and dynamic picture emerging of maize
and other domesticates not only serving as a food source, but also driving cultural development in the region. The dispersion of maize
southward through Central and South America, and northward in the American southwest can more readily be charted now through recently
dated findings from a number of areas. Although the early mechanisms of maize development continue to elude us in the archaeological
record, for now, the importance of this grain in terms of regional cultural development cannot be ignored.
(a) Washington State University (b) Florida State University (c) GeoEcoArch Research
S022 Epigenetic silencing across generations
Chandler, Vicki L-presenter [email protected](a)
Paramutation is the fascinating ability of specific DNA sequences to communicate in trans to establish meiotically heritable expression
states. Originally described at the r1 locus in maize, additional paramutation examples have been studied in maize and in other species.
Paramutation at the maize b1 locus is mediated by seven unique noncoding tandem repeats of 853 bp. Experiments will be presented
demonstrating that these repeats are both necessary and sufficient to communicate in trans to establish and maintain the meiotically
heritable expression and distinct chromatin states associated with b1 paramutation. Several genes required for paramutation have been
identified through genetic screens. These mediator of paramutation (mop) genes are required for paramutation at multiple loci, Mutator
transposon silencing, and reactivation of transcriptionally silent transgenes. Several mutants exhibit pleiotropic developmental phenotypes.
Map-based cloning of mop1 has revealed it encodes an RNA dependent RNA polymerase gene (RDR), most similar to RDR2, the RDR in
Arabidopsis that is associated with production of siRNA (short interfering RNA) molecules targeting heterochromatin. Nuclear run-on assays
reveal that the tandem repeats mediating b1 paramutation are transcribed from both strands, and the presence of tandem repeat siRNAs
depends on mop1. However, the tandem repeats are transcribed and siRNAs produced from them in all b1 alleles, even those which do not
undergo paramutation and have a single copy of the sequence. These data suggest siRNAs are involved, but are not sufficient. Models for
b1 paramutation incorporating published and unpublished data will be discussed.
(a) University of Arizona
S023 The maize inflorescence: Development, domestication and insights into grass evolution
Vollbrecht, Erik-presenter [email protected](a)
Yang, Xiang (a)
Sigmon, Brandi (a)
Unger-Wallace, Erica (a)
Li, Zhuying
(a)
Maize produces two morphologically and functionally distinct inflorescences, the tassel and ear. While the tassel and ear share
developmental programs, a key architectural difference arises from the production of a few long branches in the tassel but none in the ear.
The ramosa1 gene regulates this difference; founding meristems develop short branches when ra1 activity is high or long branches when
ra1 activity is low or absent. The ra1 gene encodes a C2H2-type putative transcription factor that, together with ra2 and ra3 (encoding a
LOB-domain protein and a trehalose-6-phoshpate phosphatase, respectively) acts in a genetic network unique to the grasses. This pathway
regulates meristems at a distance, by modulating a mobile signal that quantitatively mediates between states of inhibited vs. continued
meristem activity and branch growth. We have identified several transcription factors that interact with RA1 including the homeodomain
protein KNOTTED1. These and additional data support the involvement of specific hormone signaling pathways in transducing the mobile
signal. We have also examined roles of the ramosa pathway in natural variation. During domestication of maize from teosinte, the ra1 locus
experienced positive selection, as indicated by low ra1 nucleotide sequence diversity in both maize landraces and modern inbreds. Across
the grasses, ra2 and ra3 appear broadly conserved but ra1 is found only in the Andropogoneae, a large tribe (~80 genera and ~1,000
species) that includes maize, sorghum and Miscanthus. In the inflorescences of these taxa differential timing of ra1 expression correlates
with variable branching architecture. We propose that ra1 originated at the base of the Andropogoneae coincident with the evolution of a
specialized short branch called the spikelet pair, and that during the domestication of maize directional selection, perhaps for straight rows
of spikelet pairs in the ear, targeted a regulatory region of ra1.
(a) Iowa State University
41
S024 The codifying genome of the Palomero Mexican landrace.
Vielle-Calzada, Jean-Philippe-presenter [email protected](a)
Martinez de la Vega, Octavio (a)
Herrera-Estrella, Alfredo
(a)
Herrera-Estrella, Luis (a)
Vega-Arrenguin, Julio (a)
Hernandez-Guzman, Gustavo (a)
Ibarra-Laclette, Enrique (a)
JimenezMoraila, Beatriz (a)
Corona-Armenta, Guilermo (a)
Alvarez-Mejia, Cesar (a)
Fernandez-Cortes, Araceli (a)
de la Riva, Gustavo
(a)
Large-scale sequencing efforts concentrated in B73 will not be sufficient to fully understand maize genome organization and identify all
functional units available in the domesticated gene pool. To complement the large-scale B73 sequencing initiative and explore landrace
genomic diversity, we undertook the structural and functional characterization of the Palomero genome after estimating its genome to be
22% smaller than B73. Palomero is an ancient popcorn landrace and a member of the Central and Northern Highlands Group that produce
short individuals (140-180 cm) and grow at elevations above 2000 meters. A total of 1.2 million Sanger reads (10% HCot; 90% enzymebased methyl-filtration) and 213 pyrosequencing runs (50% methyl-filtered, 50% whole genome sequencing) were sequenced for a 3.2X
coverage. A total of 337.6 Mb have been assembled in close to 400,000 gene-enriched contigs averaging 0.91 kb in size. This effort has
been complemented by an in-depth pyrosequence-based global transcriptional analysis of the same genotype. As expected, a significant
percentage of codifying transcripts are not reported in public databases, suggesting that a large portion of the molecular and functional
diversity contained in landraces remains unexplored. We have identified a collection of ultraconserved genomic regions lacking
polymorphisms between Palomero and the inbred line B73. Our results represent an initial landmark to explore the functional diversity of
Mexican landraces in the context of maize domestication and enhancement.
(a) National Laboratory of Genomics for Biodiversity - Cinvestav Mexico
42
PB 2008
SYMPOSIA – SUNDAY JUNE 29
Date
SUNDAY
June 29
Start
8:30 AM
End
Symposium
Location
12:20 PM Symposium III - Biology of Tomato & Solanaceous
Siglo XXI Convention Center Species - Organizers: Lukas Mueller and Lus (Stella) Barrero Salon Mérida
8:30 - S031 - Roland Schafleitner, CIP, Peru - A genomics
approach to identify drought resistance traits of potato
9:10 - S032 - Fernando Carrari, Argentina - Development of
rapid strategies for testing of candidate Solanaceae QTLs
9:50 Coffee Break
10:20 - S033 - Luz Stella Barrero, Corpioca, Colombia -
Application of genomics tools - case study: tomato Solanaceae
11:00 - S034 - Felipe Cruz, Mexico - Synthesis and transfer to
the stigmatic surface of NaStEP, a vacuolar Kunitz proteinase
inhibitor homolog and its role in pollen rejection in Nicotiana
11:40 - S035 - Esther Van Der Knaap, OSU, USA - Underlying
mechanisms of diversity in tomato fruit morphology
S031 A genomics approach to identify drought resistance traits of potato
Schafleitner, Roland-presenter [email protected](a)
Gutierrez Rosales, Raymundo O (a)
Tincopa Marca, Rosalina L
(a)
Bonierbale, Merideth (a)
http://www.cipotato.org
Drought is a major limiting factor for crop productivity. To sustain food production of a growing world population, we need to improve yields
under water stress. Potato, one of the most important food crops, is considered to be drought sensitive, as even short drought periods
result in yield decline. However, germplasm with acceptable yields under drought stress is available. Particularly high drought resistance has
been found in several Andean native potato landraces, which makes them an interesting source of traits for breeding. A first resistance
candidate gene list was established based on drought tolerance studies of other plant species. Microarray expression profiling and
metabolite analysis of potato genotypes with contrasting drought resistance phenotypes revealed resistance traits including anti-oxidant
defense systems, changes in carbohydrate and amino acid metabolism contributing to osmotic adjustment, induction of specific lipid
metabolism genes pointing to membrane modifications and cell rescue mechanisms such as chaperones and increased mitochondrial
activity. On the physiological level, improved water uptake provided better yield maintenance under drought than decreased stomatal
conductance. Subsequently we compared our results with QTL information and expression databases of tomato to examine our findings on
the cross-species level. SNP detection and drought phenotyping is ongoing in different crop species to identify favorable candidate
resistance gene alleles. Presently we aim at making use of the available drought resistance traits for breeding potato with improved yield
stability under water-limited conditions. We expect cross-species genomics to facilitate the identification and use of the identified resistance
traits in different solanaceous crops.
(a) International Potato Center
S032 Development of rapid strategies for testing of candidate Solanaceae QTLs
Kamenetzky, Laura (a)
Asis, Ramon (b)
Bermudez, Luisa (c)
Bazzini, Ariel (a)
Asurmendi, Sebastian (a)
Van Sluys, Marie-Anne
(c)
Giovannoni, Jim (e)
Fernie, Alisdair R (d)
Rossi, Magdalena (c)
Carrari, Fernando-presenter [email protected](a)
The important mass of sequence information that is being released by the Tomato Genome Consortium (www.sgn.cornell.edu) is running in
parallel with the availability of new tools developed in the field of plant functional genomics. Together with results from a genome-wide
quantitative metabolic loci (QML) study of a tomato near isogenic lines (IL) population (derived from a cross between the cultivated tomato
Solanum lycopersicum and the wild species Solanum pennellii) allow identification of key regulatory points on tomato metabolism. Alongside
the dissection of previously identified QMLs for their spatial specificity, a systems-orientated view of the tomato metabolism is attempted to
functionally evaluate genetic factors that regulate metabolism. This is being carried out through: QMLs physical mapping, candidate genes
approaches, analysis of microRNAs (and their target genes mapping) and a combination of virus induced gene silencing (VIGS) and
transgenesis methods. Five genomic regions were screened in details and 127 candidate genes were found. Moreover, a genomic survey for
miRNA precursors rendered in a targeted database of putative regulatory regions. Results obtained here will be presented in the frame of
the new quality standards that producers will must to face in coming years in regards the new mandatory conditions defined by the
Regional Alimentary Code for 2010. * This research was supported by the European Commission (EU-SOL Project PL 016214) .
(a) Instituto de Biotecnologia. INTA. Argentina (b) Universidad Nacional de Cordoba. Argentina (c) Universidade de Sao Paulo. Brasil (d)
Max Planck Institute for Molecular Plant Physiology. Golm. Germany (e) Boyce Thompson Institute for Plant Research, NY, USA.
S033 Application of genomics tools - case study: tomato - Solanaceae
Barrero, Luz S.-presenter [email protected](a)
Cong , Bin (b,c)
Tanksley , Steve D. (b,c)
Due to their ease of manipulation, promiscuous character (cross and self pollination), big populations, tolerance to inbreeding, and relatively
short generation time, plants are an ideal model for genetic studies. Among plant taxa, the family Solanaceae is in turn an ideal model for
diversity and biological adaptation studies, necessary to foster plant breeding. The Andean region of South America is considered one of the
major centers of diversity and adaptation of several Solanaceae. Andean countries may take advantage of genomic information generated in
model genomes (i.e. tomato for Solanaceae) to make more efficient the improvement of less developed but socially and economically
important species. I will present a case study of application of genomics tools in tomato for Quantitative Trait Loci (QTL) characterization
and potential applications in minor Andean Solanaceae. In tomato, structural genomics have allowed the isolation of major QTLs involved in
domestication of fruit size and shape. One of these was the first QTL cloned in plants - controlling cell cycle. The second QTL - controlling
organ number (carpel/locule) - has been recently cloned. The research on this second major QTL traces back to 2001 using the genomics
43
tools available underway. The first studies allowed the identification of tomato loci controlling the number of locules in a large sampling of
big sized multilocular varieties and the nature and timing of developmental events controlled by the major locus. The latter studies allowed
the isolation of this locus by positional gene cloning. With the sequencing and annotation of the tomato genome and other genomics tools
developed it is expected that QTL cloning in this species will be more time effective than in the past. However, what is the situation with
species where long generation times and little genomic developments are available? Due to high genomic conservation at the micro and
macro levels, species in the Solanaceae family may take advantage of tools from model species. Comparative genomic tools are being used
in underrepresented but regionally important Solanaceae crops with great potential for QTL identification to further genetic improvement.
(a) Corporacion Colombiana de Investigacion Agropecuaria, Corpoica, Colombia (b) Department of Plant Breeding & Genetics, Cornell
University, Ithaca, NY 14853 (c) Department of Plant Biology, Cornell University, Ithaca, NY 14853
S034 Synthesis and transfer to the stigmatic surface of NaStEP, a vacuolar Kunitz proteinase inhibitor homolog and its role
in pollen rejection in Nicotiana
Jimenez-Duran, Karina (a)
Busot, Grethel (a)
Ibarra-Sanchez, Claudia (a)
McClure, Bruce (b)
Cruz-Garcia, Felipe-presenter
[email protected](a)
Self-incompatibility (SI) systems prevent self-inbreeding and promote genetic diversity within species. Pollen rejection response is
genetically controlled by the locus S. In Solanaceae, the S locus encodes the S-RNase or female determinant and the S-locus F box protein
(SLF) or male determinant. Both are essential but not enough for pollen rejection, because unlinked genes to S-locus are also required. We
identified and characterized a stigma-specific protein from N. alata, NaStEP (N. alata Stigma Expressed Protein), which is homologous to
Kunitz-type proteinase inhibitors. However, activity gel assays showed that NaStEP is not a tripsin inhibitor. Immunohistochemical and
protein-blot analyses revealed that NaStEP is only detectable in stigmas of SI species N. alata, N. forgetiana and N. bonariensis, but not in
the SC species N. tabacum, N. plumbaginifolia, N. benthamiana, N. longiflora and N. glauca studied. NaStEP contains the vacuolar targeting
sequence NPIVL, and immunocytochemistry experiments showed vacuolar localization in unpollinated stigmas. After self-pollination or
pollination with pollen from the SC species N. tabacum or N. plumbaginifolia, NaStEP was found in the stigmatic exudate. Synthesis of this
protein was strongly induced in N. alata following incompatible pollination with N tabacum pollen. The transference of NaStEP to the
stigmatic exudate was accompanied by perforation of the stigmatic cell wall, which appeared to release the vacuolar contents to the
apoplastic space. Once in the exudate, NaStEP is associated with incompatible and compatible pollen tubes. Preliminary experiments with
Nicotiana transgenic plants, in which NaStEP was silenced, show that SI is breakdown in these plants, indicating that NaStEP is part of the
pollen rejection pathway in Nicotiana.
(a) Depto. de Bioquimica, Facultad de Quimica. Universidad Nacional Autonoma de Mexico (b) Division of Biochemistry, 105 Life Sciences
Center. University of Missouri-Columbia
S035 Underlying mechanisms of diversity in tomato fruit morphology
van der Knaap, Esther-presenter [email protected](a)
Rodriguez, Gustavo (a)
Xiao, Han (a)
http://www.oardc.ohio-state.edu/vanderknaap/
The domestication of tomato (Solanum lycopersicum) for its fruit characters resulted in a large collection of varieties that differ in fruit
morphology. Over the past few years, the underlying molecular basis for some of the diversity has been unraveled. The knowledge of genes
that control morphology permits insights into processes that regulate fruit shape and patterning while it also illuminates how domestication
shaped tomato fruit. To date, we know of three genes that control tomato fruit morphology. One gene, FW2.2 controls fruit mass whereas
the other two genes, OVATE and SUN control fruit shape. We recently cloned SUN and found that the locus arose via an unusual mutation,
underscoring the many different ways by which genome evolution and phenotypic changes occur (1). SUN controls elongated fruit shape by
increasing fruit length and reducing fruit width, and its effect is most strongly exhibited after fertilization. The effect of SUN on fruit
morphology is to increase the oval shape of the seed part of the fruit. The gene encodes a member of the IQ domain family of proteins
which have been hypothesized to regulate hormone and/or secondary metabolism levels (1). OVATE also controls elongated fruit shape.
Contrary to SUN, OVATE exhibits its most dramatic effect on fruit shape prior to fertilization. The largest effect of OVATE is on the eccentric
positioning of the seed in the fruit. OVATE encodes a member of the Ovate Family Proteins (OFP) that acts as a repressor of transcription
(2) and interacts with KNOX and BELL type homeodomain proteins (3) in Arabidopsis. FW2.2 controls fruit weight and the encoded protein
has been shown to interact with regulators of the cell cycle (4) in tomato. Most of the variation present in the cultivated tomato germplasm
is attributed to either SUN or OVATE in accessions carrying elongated fruit whereas FW2.2 appears be fixed. Funded by NSF DBI 0227541.
1. Xiao et al, 2008. Science 319: 1527. 2. Wang et al, 2007. Plant J 50: 858. 3. Hackbusch et al, 2006. PNAS 102: 4908. 4. Cong and
Tanksley 2006. Plant Mol Biol 62: 867.
(a) The Ohio State University/OARDC
44
PB 2008
Date
SUNDAY
June 29
Start
3:00 PM
End
Symposium
Location
6:10 PM Symposium IV - Martin Gibbs Medal - Organizer: Richard Siglo XXI Convention Center A. Jorgensen
Salon Mérida
3:00 - S041 - Sue Rhee - Discovering new enzymes by
combining computational and metabolomic approaches in
Arabidopsis and translating metabolic network knowledge from
model to crop plants
3:40 - S042 - Rodrigo Gutierrez - VirtualPlant: A software
platform to support systems biology research in the postgenomic era
4:20 Coffee Break in Exhibit Hall
4:50 - S043 - Eric Kramer - Models of auxin transport and
action: from Arabidopsis to Populus
5:30 - S044 - Richard A. Jorgensen - The iPlant Collaborative:
A cyberinfrastructure-centered community for a new plant
biology
S041 Discovering new enzymes by combining computational and metabolomic approaches in Arabidopsis and translating
metabolic network knowledge from model to crop plants
Rhee, Seung-presenter [email protected](a)
A large portion of protein-encoding genes in the Arabidopsis genome remains unknown in its biochemical function. Although over 95% of
the 283 pathways in the Arabidopsis pathway database AraCyc (http://www.arabidopsis.org/biocyc/index.jsp) have been experimentally
verified, one out of four reactions is still missing the corresponding gene that encodes the enzyme. By using a combination of sequencebased and function-based inference methods for predicting gene function, we identified several hundred genes that were predicted to
encode enzymes that catalyze unannotated reactions in pathways and chose 18 genes to characterize further using metabolomics
approaches. By combining the analytical capabilities of six laboratories, a plant metabolomics consortium (www.plantmetabolomics.org)
detected the concentration levels of around 1700 unique compounds from the 18 Arabidopsis lines carrying homozygous knock-out
mutations of the selected genes. We identified the significantly altered compounds in different genotypes and found that different mutants
tend to affect the concentration level of distinct sets of compounds. To better define the function of these enzyme candidate genes, we
mapped approximately 350 compounds back to the AraCyc pathways and developed a weighted ranking method to identify the significantly
affected pathways based on the metabolite profiles. After down-weighing the pathways based on the frequency of occurrence in the
genotypes and the portion of observed metabolites, the affected pathways were ranked based on the extent of changes of the metabolites.
The detailed results of this project will be presented in the poster. Currently we are using additional approaches to analyze the changes in
the metabolome as a result of genetic perturbation by representing AraCyc pathways as a bipartite graph in order to identify the reporter
reactions that are responsible for the observed changes in the metabolites. In addition, we are developing an infrastructure called the Plant
Metabolic Network (PMN) to represent plant metabolism in both computer- and human-readable ways to facilitate translation of knowledge
gained from one organism to another to facilitate metabolic network modeling, enzyme and pathway discovery, and pathway engineering.
At the center of the PMN is PlantCyc, a database containing pathways and their catalytic enzymes and genes, as well as compounds from
many plant species. The majority of pathway diagrams in PlantCyc are manually extracted from the plant literature. They are either
supported by experimental evidence or are based on expert hypotheses. PlantCyc will be used as a reference database to predict metabolic
pathways of newly sequenced genomes. I will present how PlantCyc and its derived databases can be used to model metabolic networks
and facilitate enzyme and pathway discovery.
(a) Carnegie Institution
S042 Models of auxin transport and action: from Arabidopsis to Populus
Kramer, Eric M-presenter [email protected](a,b)
http://minerva.simons-rock.edu/~ekramer/
In the last few years computer simulation has become an increasingly common technique to evaluate models of auxin action in plant growth
and development. In arabidopsis roots, models with micron-scale resolution have been used to examine the role of auxin in gravitropism,
meristem maintenance, root hair development, and lateral root emergence. In the cambium of Populus trees, models with mm-scale
resolution have clarified the role of an auxin gradient in wood grain pattern formation. We will review these models, their successes and
limitations, and point the way to future work. The experimental validation of model assumptions will be emphasized.
(a) Bard College at Simon's Rock, Great Barrington, MA (b) Centre for Plant Integrative Biology, Nottingham, UK
S043 VirtualPlant: A software platform to support systems biology research in the post-genomic era.
Katari, Manpreet S (a)
Nowicki, Steven D (a)
Aceituno, Felipe F (b)
Poultney, Chris (c)
Nero, Damion C (a)
Chiaromonte,
Francesca (c)
Shasha, Dennis (c)
Coruzzi, Gloria M (a)
Gutierrez, Rodrigo A-presenter [email protected](b,a)
http://virtualplant.bio.puc.cl
In the post-genomic era, data generation is no longer the limiting factor for advancing biological research. Instead, data integration,
analysis and interpretation are the bottlenecks and challenges that biologists face everyday in genomic research. We wish to aid biologists
to take advantage of the burgeoning amount of genomic data, by developing a software platform that enables scientists to visualize,
integrate and analyze genomic data from a systems biology perspective. We term this software platform VirtualPlant. The VirtualPlant
platform integrates genome-wide data concerning the known and predicted relationships among genes, proteins and molecules, as well as
genome-scale experimental measurements. VirtualPlant provides mathematical and statistical methods to help analyze and summarize the
data. VirtualPlant implements and combines these quantitative and qualitative (e.g. visual) approaches to data integration and analysis
using a web-accessible interface. VirtualPlant can be used to help biologists mine genomic data to address questions such as: What are the
molecular mechanisms by which internal and external perturbations affect processes and gene networks controlling growth and
45
development? As a proof of principle, we will discuss how VirtualPlant was used to identify regulatory hubs that control nitrogen-responsive
gene networks. Whereas the VirtualPlant project was developed specifically for Arabidopsis, the data structures, algorithms, and
visualization tools are designed in a species-independent way. Our future plans include providing support for other plant species. The
VirtualPlant system is available from http://www.virtualplant.org
(a) Department of Biology, New York University. (b) Departmento de Genetica Molecular y Microbiologia. P. Universidad Catolica de Chile.
(c) Courant Institute of Mathematical Sciences. New York University.
S044 The iPlant Collaborative: A cyberinfrastructure-centered community for a new plant biology
Jorgensen, Richard-presenter [email protected](a)
The iPlant Collaborative (iPC) is a University of Arizona-led consortium consisting of UA, Cold Spring Harbor Lab, Purdue Univ., Arizona State
Univ. and UNC-Wilmington, that was organized in response to NSF‘s Plant Science Cyberinfrastructure Collaborative (PSCIC) program.
Importantly, the iPC is mandated to be a cyberinfrastructure collaborative, rather than purely a cyberinfrastructure, and to be ―by, for and
of‖ the plant science community. The driving force of the Collaborative must be grand challenge questions in plant science. The
Collaborative must enable multi-disciplinary teams to address grand challenges; it must train the next generation of plant scientists in
‗computational thinking‘; and it must be able to constantly reinvent itself as needs and technologies change. With these principles in mind,
we have developed the iPlant Collaborative. The act of selecting grand challenges must be community-driven, and so during the first year of
funding, we will host a series of workshops, each focused on a specific area of plant biology, but with participants cutting across the
spectrum of computing and biological sciences. The goal of each workshop will be to identify the ―grand challenge‖ questions in that field,
as well as the necessary strategies and approaches that will be needed to solve the question(s). Self-forming Grand Challenge Teams from
the community will then work with iPC personnel to develop a ‗Discovery Environment‘ (DE), which will be a cyberinfrastructure within which
the team and the community will address and solve the grand challenge and will be able to perform related research analyses. DEs
designed for different grand challenges will overlap and eventually coalesce, thourgh partnerships with other cyberinfrastructure efforts, into
a comprehensive cyberinfrastructure for the plant sciences. The iPC‘s cyberinfrastructure will provide two main capabilities. First, it will
provide access to world-class physical infrastructure – for example, persistent storage and compute power via local and national resources.
Second, it will provide analytical tools and services that promote, interactions, communications and collaborations and that advance the
understanding and use of computational thinking and analysis in plant biology. The impact of the iPC project will not be limited to the
solution of currently intractable grand challenge questions because at its core the iPC is actually a community building and educational
enterprise designed not only for research but also to facilitate education and outreach. Grand Challenge teams and iPC staff will work
together to ensure development of Discovery Environments that meet this need. Thus, education and outreach efforts will permeate the
iPlant Collaborative.
(a) University Of Arizona
46
PB 2008
SYMPOSIA – MONDAY JUNE 30
Date
MONDAY
June 30
Start
8:30 AM
End
Symposium
Location
12:20 PM Symposium V - Tropical Agriculture - Organizers: Richard Siglo XXI Convention Center Sayre & Miguel A. Gómez-Lim
Salon Mérida
8:30 - S051 - Richard Sayre - Biofortification of cassava to
alleviate malnutrition; the biocassava plus program
9:15 - S052 - Miguel A. Gómez-Lim - Genetic transformation of
tropical plant species
10:00 Coffee Break
10:30 - S053 - Marcos Buckeridge - A novel alpha-
galactosidase from coffee is likely to control mannan fine
structure in developing seeds
11:15 - S054 - Justin Maresh - Alkaloid biosynthesis in
Madagascar periwinkle (Catharanthus roseus)
S051 Biofortification of cassava to alleviate malnutrition; the biocassava plus program
Sayre, Richard T-presenter [email protected](a)
http://biocassavaplus.org/
BioCassava Plus is a multidisciplinary team of scientists developing a more nutritious cassava for sub-Saharan Africans. Inadequate nutrition
is the single greatest cause of excess mortality, morbidity and suffering in sub-Saharan Africa. The objective of BioCassava Plus is to reduce
malnutrition by providing complete nutrition in a single staple crop, cassava (Manihot esculenta). Over two hundred and fifty million Africans
rely on the starchy root crop cassava as their staple food. Cassava roots, however, have the lowest protein:energy ratio of all the worlds
major staple crops. A typical cassava-based diet provides less than 30% of the minimum daily requirement for protein and only 10-20% of
the required amounts of iron, zinc, vitamin A and vitamin E. BioCassava Plus employs modern biotechnologies to improve the health of
Africans through development and delivery of novel cassava germplasm with increased nutrient (zinc, iron, protein and vitamins A and E)
levels. Effective delivery of biofortified cassava will be achieved by linking optimal nutritional traits with improved post-harvest durability of
the storage roots, elimination of toxic cyanogenic glycosides, and elevated resistance to viral disease; characteristics required to provide
ample amounts of foodstuffs and incentives for farmers to adopt and sustain biofortified cassava cultivars. Currently, proof-of-concept has
been achieved for our target objectives for elevated vitamin A and E, zinc, iron, protein and additional constraints including, virus resistance,
acyanogenesis and extended shelf life. Transgenic strategies for achieving these results will be discussed.
(a) Ohio State University
S052 Genetic transformation of tropical plant species
Gómez Lim, Miguel-presenter [email protected](a)
Biotechnology has had a dramatic impact in different fields. This is particularly evident in horticulture where the application of biotechnology
has produced, in a short period of time, exciting results. Clearly, an essential prerequisite has been the development of methods for in vitro
culture and regeneration of the crop. In this respect, tropical trees have proved somewhat difficult to in vitro manipulation. Nevertheless, it
is now possible to genetically manipulate several tropical crops with varying efficiencies. This has opened the door for a number of
interesting possibilities to control a series of diseases and to extend the postharvest life, a problem that particularly afflicts some tropical
fruits. During the talk, progress on genetic transformation at CINVESTAV-Irapuato of three very important tropical crops avocado, banana
and papaya aimed at modifying specific traits, will be discussed, together with recent results on the use of genomics and proteomics on
some of these crops.
(a) CINVESTAV Irapuato
S053 A novel alpha-galactosidase from coffee is likely to control mannan fine structure in developing seeds
Silva, Clovis O (a,b)
Ferreira, Lucia (e)
Marraccini, Pierre (d,e)
Vieira, Luiz GE (e)
Labate, Monica TV (c)
Labate, Carlos A
(c)
Tine, Marco AS (b)
Tonini, Patricia P (a)
Buckeridge, Marcos S-presenter [email protected](a)
Coffee seeds store pure mannan as the principal reserve for seed germination. However, during fruit development, seeds accumulate first
galactomannan, which is degalactosylated towards the end of seed development. In this work, a novel alpha-galactosidase from developing
coffee fruits has been purified and characterized. Its activity (optimim pH 6-7) peaks at the stage when galactomannan degalactosylation
occurs, i.e. between 150 and 170 days after anthesis (DAA). Using an antibody against alpha-galactosidase from guar seeds, we found that
the enzyme is present mainly in the cytosol near the cell walls of endospermic cells. These results, together with the range of pH optima,
suggest that the enzyme probably acts on nascent galactomannan when it is at the Golgi. Indeed, some of the activity was found in Golgi
fractions prepared from developing seeds,although most of it is soluble. The coffee enzyme showed high specificity towards galactomannan
isolated from its own seeds and presented little action on other galactomannans. N-terminal and internal sequences were obtained and the
corresponding full-length cDNA sequence named CaGAL2 was isolated from endosperm tissue CaGAL2 expression was highly detected
mainly in developing endosperm between 150 and 170 DAA at the time coinciding with the peak of enzyme activity. High expression
CaGAL2wexpression was also observed in developing endosperm of C. racemosa. However, CaGAL2 expression was not observed in the
perisperm and pericarp as well as in other tissues (leaf, root, flower) from C. arabica. The search in public database with the protein
CaGAL2 did not show similarity with other reported alpha-galactosidases, suggesting that this is a novel protein. As this is the enzyme that
makes coffee insoluble during maturation because it degalactosylates mannan, it may be speculated that the control of expression of
CaGAL2 could be used to develop more productive coffee varieties for soluble coffee production. Financed by CNPq and FAPESP
(a) University of Sao Paulo, Institute of Biosciencies, Department of Botany, SP-Brazil (b) Institute of Botany, Section of Plant
Physiol.Biochem, SP-Brazil (c) University of Sao Paulo, ESALQ-USP, Department of Genetics, SP-Brazil (d) Cirad UMR DAP-France (e)
Agronomic Institute of Parana PR, Brazil
47
S054 Alkaloid biosynthesis in Madagascar periwinkle (Catharanthus roseus)
Maresh, Justin J-presenter [email protected](a,b)
O'Connor, Sarah E (a)
http://web.mit.edu/soconnor/www/
Madagascar periwinkle (Catharanthus roseus), produces more than 100 terpene indole alkaloids with varied biological activities. We have
generated novel alkaloids by feeding synthetic substrates to cell cultures. In particular, we have isolated novel catharantine analogs that
were reacted to produce analogs of the anti-tumor agent vinblastine. Through studies of the mechanism, substrate specificity, and
mutasgenesis of the central enzyme of the terpene indole alkaloid biosynthetic pathway, we are further exploring the capacity of this
pathway for production of novel alkaloids.
(a) Massachusetts Institute of Technology, Department of Chemistry (b) DePaul University, Department of Chemistry
48
PB 2008
SYMPOSIA – TUESDAY JULY 1
Date
TUESDAY
July 1
Start
End
2:30 PM
Symposium
6:20 PM Symposium VI – ASPB President’s Symposium Organizer: C. Robertson McClung
2:30 - S061 - C. Robertson McClung - Timing is everything
3:10 - S062 - Edgar Spalding - Seedling establishment seen
Location
Siglo XXI Convention Center Salon Mérida
through the eyes of a computer
3:50 Coffee Break
4:20 - S063 - Steve Kay 5:00 - S064 - Scott Poethig - Turning over a new leaf: The
regulation of vegetative phase change in Arabidopsis
5:40 - S065 - Annie Schmitt - Arabidopsis in the real world:
Flowering time pathways in natural environments across the
species climatic range
S061 Timing is everything
McClung, C. Robertson-presenter [email protected](a)
http://www.dartmouth.edu/~rmcclung/index.html
‗When?‘ is my favorite question. We are used to thinking in three dimensions, but there is a fourth dimension, time. This presidential
symposium will explore aspects of plant biology at different time scales: seconds, days, weeks to months, and centuries. I will address
circadian rhythms, but my view of the biological clock has been evolving and my talk will discuss both natural variation and evolution of
clock genes. One of the central premises of the study of circadian rhythms is that a functional circadian clock enhances organismal fitness.
We have tested the hypothesis that mutational differences in clock genes among accessions are subject to selection through sequence
analysis of PSEUDO-RESPONSE REGULATOR 7 (PRR7; At5g02810) from >100 Arabidopsis accessions. There is a significant excess of
replacement mutations relative to synonymous mutations (20 and 5, respectively; p<0.005), consistent with diversifying selection at the
PRR7 locus. This cannot be attributed to selection occurring at adjacent loci, as one flanking gene shows excess synonymous mutations (6
replacement and 31 synonymous; p<0.001) and the other flanking gene shows roughly equal numbers of replacement and synonymous
mutations (10 and 14, respectively; p>0.5), consistent with purifying and neutral selection, respectively. This suggests selection for multiple
allelic variants at the PRR7 locus, which is consistent with distinct PRR7 alleles contributing differentially to organismal fitness in different
environments. We are currently testing whether these different PRR7 alleles are functionally equivalent. Enhancement of crop productivity is
critical to efforts to provide plant biomass for food, fiber and fuel. The interaction of clock function with the environment offers opportunities
to enhance crop productivity through tailoring cultivars to their local temporal and photoperiodic environment. It therefore becomes
important to ask to what extent the Arabidopsis clock model can be generalized among plants. To this end, we and others are developing
diverse model and crop species as systems for study of clocks. We have identified quantitative trait loci (QTL) contributing to clock function
in the model crop species Brassica rapa and are currently attempting to identify the responsible genes. My work on circadian rhythms is
supported by grants from the National Science Foundation (MCB-0343887 and IOB-0517111) and from the United States-Israel Binational
Science Foundation (2005223).
(a) Department of Biological Sciences, Dartmouth College
S062 Seedling establishment seen through the eyes of a computer
Spalding, Edgar P.-presenter [email protected](a)
http://phytomorph.wisc.edu
Seedling establishment is a developmental phase marked by profound changes in form and function. The embryo within the seed
dynamically transforms into a self-sufficient, photoautotrophic seedling that anchors a new life cycle. Seedling establishment is critical yet
highly vulnerable to the slings and arrows of a changeable world. Perhaps for this reason, many species such as Arabidopsis progress
through it rapidly and exquisitely in tune with the environmental influences of light and gravity. A seedling properly adapted and poised for
success is thus expeditiously produced. An understanding of how establishment unfolds from the genome through developmental and
physiological mechanisms is conceivably attainable through the integrated application of several modern experimental approaches, one of
which should be automated analysis of organ size and shape so that effects of mutations and/or conditions can be quantified. Computer
vision applications for this purpose have been recently developed, and will be described. The raw data are times series of electronic images
taken every few minutes. The measured outputs include parameters such as hypocotyl and root growth rates, apical hook angle, root tip
angle, distribution of curvature along the root axis, and lateral root descriptors. Two particular cases will receive special attention. First will
be the effects of altered auxin distribution caused by mutations in Multidrug Resistance-like (MDR) genes on root growth and curvature.
Second will be the importance of subcellular localization of the cry1 blue light receptor on its photomorphogenic actions. In the end, recent
computer vision studies that link the actions of MDR-mediated auxin transport to cry1-dependent photomorphogenesis will be presented.
(a) University of Wisconsin
S063 To Be Announced
Kay, Steve-presenter [email protected](a)
TBA
(a) University Of California
S064 Turning over a new leaf: The regulation of vegetative phase change in Arabidopsis
Poethig, Scott-presenter [email protected](a)
Arabidopsis undergoes several major transitions during its development. The most obvious of these is the transition from vegetative to
49
reproductive growth, when the shoot stops making leaves and vegetative buds and begins to produce flowers. This event is preceded by
the transition from a juvenile to an adult phase of vegetative development (vegetative phase change) which is marked by changes in leaf
morphology and by an increase in reproductive competence. Microarray analysis of gene expression in 1 mm leaf primordia and fully
expanded leaves from six different positions on the shoot demonstrates that many genes are differentially expressed during shoot
development. Only some of these genes are expressed in a phase-specific fashion. Vegetative phase change is mediated by two temporallyregulated miRNAs--miR156 and miR172. miR156 controls most of the morphological changes that occur during vegetative phase change
through its effect on the expression of 10 members of the SPL family of transcription factors. miR172 acts downstream of miR156, and
regulates a subset of phase-specific vegetative traits as well as flowering time. The structure of the pathway(s) that control vegetative
phase change, and the factors that regulate the timing of this process, will be discussed.
(a) University of Pennsylvania
S065 Arabidopsis in the real world: Flowering time pathways in natural environments across the species climatic range
Schmitt, Johanna-presenter [email protected](a)
Flowering is a critical life history event, and the seasonal timing of flowering is often under strong natural selection. In order to flower
during favorable seasonal conditions, plants must integrate and respond appropriately to multiple environmental signals, such as day length,
ambient temperature, and vernalization. These external signals mediate several converging developmental signaling pathways, which have
been well characterized in model species such as Arabidopsis thaliana under constant laboratory conditions. However, very little is known
about the balance and sensitivity of different pathways to complex environmental cues under variable natural conditions in different
climates and seasons, or how natural variation in flowering genes is expressed in natural environments. To measure the sensitivity of
flowering time to perturbations in different signaling pathways in natural seasonal environments, we grew a set of European A. thaliana
ecotypes as well as mutants of key flowering time genes under natural conditions in replicated field experiments in 5 sites across the
species native European climatic range. We also measured temperature and light environments experienced by plants throughout the
growing season in each site. Expression of natural variation in flowering time differed across sites and seasons, as did associations with
allelic variation in candidate flowering time genes such as FRIGIDA. Specific mutants were accurate phytometers of vernalization and
photothermal cues experienced by plants under natural conditions, demonstrating that the relative balance of different signaling pathways
varies widely across geographic locations and seasons. Moreover, the sensitivity of flowering time to genetic perturbation of signaling
pathways varied seasonally, and was dramatically amplified for cohorts germinating in a narrow temporal window in late summer. Within
this window, mutational changes can cause life history conversions between spring-flowering winter annuals and autumn- flowering rapid
cycling cohorts. Outside of this window, mutant phenotypes are dampened and do not result in life history conversions as predicted from
phenotypes commonly observed in chamber experiments. Thus, in the wild, the impact of mutations in flowering pathways depends
critically upon climate and the seasonal timing of germination.
(a) Brown University
50
PB 2008
MINISYMPOSIA – SATURDAY JUNE 28
Date
SATURDAY
June 28
Start
3:00 PM
End
Minisymposium
Location
4:40 PM Minisymposium 1 - Education Outreach - Chair: Jane Ellis Siglo XXI Convention Center 3:00 - M0101: Adán Colon-Carmona - An inquiry-based plant Salon Merida
genomics course and workshop: Phenotype to gene and back
again
3:25 - M0102: Chris Cullis - Lost crops of Africa: Involving
undergraduates in their rediscovery and development
3:50 - M0103: Nancy Moreno - Web-based biology teaching
resources
4:15 - M0104: Burkhard Schulz/Michael Van Oosten - Video
podCasts as a teaching tool in Plant Physiology laboratory
courses
M0101 An inquiry-based plant genomics course and workshop: Phenotype to gene and back again
Colon-Carmona, Adan -presenter [email protected](a)
Springer, Patricia (b,b)
Engaging high school and undergraduate students in research projects during course work is both difficult and time-consuming. Moreover,
how does one integrate plants, particularly Arabidopsis, to increase interest and excitement in studying genomics? We have developed a
two-step year-long approach to incorporate Arabidopsis 2010 research projects into Boston area biology high school classrooms. This
includes a recruitment strategy at area biotechnology and education symposia, an intensive one-week summer workshop for high school
teachers, and an academic year follow-up program. In a plant biology undergraduate course, the laboratory portion is used to facilitate a
semester-long research experience using genetic resources available from the Arabidopsis community and which are being generated as
part of an Arabidopsis 2010 project. Undergraduates conduct self-directed projects to investigate their own hypotheses on a specific
member of the gene family being studied. At the end of the course, projects are presented in a symposium format. A summary of the
activities and these experiences with students and teachers will be presented.
(a) Univ. of Massachusetts Boston (b) Univ. of California Riverside
M0102 Lost crops of Africa: Involving undergraduates in their rediscovery and development
Cullis, Christopher A.-presenter [email protected](a)
Lost crops of Africa: Involving undergraduates in their rediscovery and development Christopher A. Cullis Department of Biology, Case
Western Reserve University, Cleveland, OH 44120 e-mail: [email protected] A laboratory course has been designed to engage undergraduate
students in developing useful DNA markers for under-utilized crops in Africa while also getting an international experience. This course
specifically tries to avoid a common preconception of laboratory courses, namely, if the experiment works then there is not much
satisfaction since the experiments are set up to ensure that they work and there is a definitive answer to the questions posed. The focus of
the course for the past 3 years has been on developing useful DNA markers, with each class building on previous years results. The crops
initially targeted were bambara nut, banana, cassava, cowpea and marama, but marama bean (Tylosema esculentum) has now been
selected as the focus crop for the next few years. These student efforts should result in a high density SSR molecular map of marama. The
international component involves web video links for live interactions between students and faculty in Cleveland, Pretoria and Windhoek,
where the data will be put to direct use in a proposed breeding project. Dr. Percy Chimwamarumbe from Namibia was an active participant
in the course for two weeks in Fall 2007. Up to 36 students are enrolled each semester (the course is being offered twice a year) and it has
been positively and enthusiastically evaluated by the students. The development of this course was supported by a World-Wide Learning
Experience grant, a McGregor Fund initiative in the College of Arts and Sciences, Case Western Reserve University (to CAC) and a grant
from the Kirkhouse Trust (to PC).
(a) Case Western Reserve Universitiy
M0103 Web-based biology teaching resources
Moreno, Nancy P-presenter [email protected](a)
Erdmann, Deanne B (a)
Tharp, Barbara Z (a)
GrandPre, Tadzia (a)
http://www.bioedonline.org
BioEd Online (www.bioedonline.org), Baylor College of Medicine‘s award-winning website, offers up-to-date biology content, news, and
professional development resources appropriate for educators of all levels, including undergraduate instructors. Learn how to access peerreviewed, annotated PowerPoint slides; entertaining videos to focus students‘ attention; streaming video content and ―how-to‖ laboratory
presentations; inquiry-based lessons; and science education outreach resources, including teacher short courses. An asynchronous,
problem-based undergraduate course on genetics and genomics will be launched in fall 2008.
(a) Baylor College of Medicine
M0104 Video podCasts as a teaching tool in Plant Physiology laboratory courses
Schulz, Burkhard-presenter [email protected](a)
Nucera, Diana J (a)
Holladay, Steven (a)
Van Oosten, Michael (a)
http://www.hort.purdue.edu/hort/people/faculty/schulz.shtml
We have developed a set of educational tools in form of video archives to enhance the student ability to learn and appreciate plant biology.
We present the production, student use, and assessment of student-produced video podcasts used to augment plant physiology labs at
Purdue University. Our project addresses the diverse student composition participating in plant physiology (HORT301) at Purdue University.
One of the problems we are able to address is the knowledge gap of students with less experience in experimentation while still challenging
students who are already familiar with the methodology. Our goals are to enable the students to 1) identify basic terminology related to lab
and research procedures, 2) to identify single basic steps in lab and research procedures, 3) to carry out basic steps in lab and research
procedures and to 4) develop a positive attitude towards the process of scientific discovery. We will discuss the process and obstacles
51
involved in setting up laboratory podcasts as well as an evaluation of the feedback we have collected from undergraduate students that
have particpated in the enhanced learning experience.
(a) Purdue University, Department of Horticulture, West Lafayette, IN 47907, USA
Date
SATURDAY
June 28
Start
3:00 PM
End
Minisymposium
Location
4:40 PM Minisymposium 2 – Organelle Biology and Protein
Siglo XXI Convention Center Trafficking – Chair: Marisa Otegui
Salon Valladolid
3:00 - M0201: Sally Mackenzie - Non-AUG translation initiation
in plant protein dual targeting
3:25 - M0202: Steven M. Smith - Defining the plant peroxisome
and modeling its function
3:50 - M0203: Danny J Schnell - The role of the TOC-TIC
translocons in regulated preprotein targeting to plastids
4:15 - M0204: Marisa S. Otegui - The ESCRT related CHMP1A
and B proteins mediate the localization of the auxin efflux
carrier PIN1 at the plasma membrane and are required for
embryo development.
M0201 Non-AUG translation initiation in plant protein dual targeting
Wamboldt, Yashitola (a)
Mohammed, Saleem (a)
de Paula, Wilson (a)
Mackenzie, Sally-presenter [email protected](a)
Post-endosymbiotic evolution has produced several mechanisms to facilitate the dual targeting of plant proteins. In plants, dual targeting to
mitochondria and plastids involves various means of producing alternative amino termini for a single gene product. We are investigating
alternative translation initiation as one such means. Our study includes both in vivo GFP localization and in vitro transcription-translation
systems to assess protein targeting. We have identified, within a single gene, multiple alternative translation initiation sites involving CTG
and ATA initiator codons. In each case, an adenine resides at the -3 position to the initiation point, and other cis sequence features are also
important to selection of a non-AUG initiator. The alternative translation initiation process that we have studied involves cap-dependent
ribosome scanning rather than internal ribosome entry mechanisms and appears to be modulated developmentally.
(a) University of Nebraska - Lincoln
M0202 Defining the plant peroxisome and modeling its function
smith, steven M.-presenter [email protected](a,b)
bussell, John D. (a,b)
Zhou, Wenxu (a,b)
Millar, Harvey (a,c)
Small,
Ian D. (a,c)
Castleden, Ian (a,c)
Che, Ping (a,b)
Eubel, Holger (a)
Meyer, Etienne H. (a)
O'Toole, Nick
(a,c)
Pracharoenwattana, Itsara (a,b)
Taylor, Nicolas (a)
Wiszniewski, Andrew (a,b)
http://www.plantenergy.uwa.edu.au
Predictions of peroxisomal proteins based on putative PTS sequences have identified between two and three hundred proteins (Reumann et
al, Plant Physiol. 136:2587-608, 2004). Proteome analysis of isolated Arabidopsis leaf peroxisomes has identified 78 proteins (Reumann et
al, Plant Cell 19:3170-93, 2007). We have purified organelles from Arabidopsis cell cultures and defined a set of over 100 peroxisomal
proteins extending the total number identified to approximately 130. Confirmation of the peroxisomal location of some of these proteins is
being established using GFP fusions. Many of these proteins are recognized peroxisomal proteins with established functions, while others
are of unknown function. To investigate protein functions and examine their possible relationships we have interrogated functional genomics
data and are systematically isolating mutants for phenotypic analysis. These studies provide us with an inventory of component parts with
which we are building a model of peroxisome function. The model is being refined and extended through continued addition of new
information and testing using reverse genetics and phenotypic analysis. The aim is to build a complete in silico model of the peroxisome
which will allow us to undertake rational design of key functions such as those involved in energy metabolism, oxidative stress and plant
development.
(a) ARC Centre of Excellence in Plant Energy Biology, University of Western Australia (b) Centre of Excellence for Plant Metabolomics,
University of Western Australia (c) Centre of Excellence in Computational Systems Biology, University of Western Australia
M0203 The role of the TOC-TIC translocons in regulated preprotein targeting to plastids
Schnell, Danny J-presenter [email protected](a)
Lee, Jeonghwa (a)
Wang, Fei (a)
Plastid biogenesis is dependent upon the coordinated expression and import of more than 3000 nucleus-encoded proteins during plant
development. The majority of plastid proteins are synthesized with cleavable transit peptides, and their import is mediate by the TOC-TIC
translocon system. The translocon at the outer envelope membrane (TOC) recognizes the transit peptides of plastid preproteins and initiates
import by transferring the preprotein to a protein-conducting channel. The TOC complex associates with the translocon at the inner
envelope membrane (TIC) to facilitate simultaneous transport of proteins across the double membrane of the envelope. The receptor
systems of TOC complex play critical roles in the selective import of distinct classes of preproteins. The ability of the receptors to regulate
import via their intrinsic GTPase activities appears to play a critical role in coordinating changes in nuclear gene expression with protein
import during plant development. At the inner membrane, the TIC system not only mediates protein translocation, but it also plays a central
role in directing newly imported proteins to their proper suborganellar compartment (e.g. the stroma, inner membrane or thylakoid). We
have utilized combined in vitro and in vivo approaches to understand the mechanistic details of TOC-TIC function in protein targeting and
plastid development. We will discuss our recent studies aimed at understanding how the TOC and TIC translocon complexes regulate the
import of distinct classes of nucleus-encoded preproteins and coordinate subsequent sorting of these proteins to their proper location within
the plastid.
(a) University of Massachusetts
52
PB 2008
M0204 The ESCRT related CHMP1A and B proteins mediate the localization of the auxin efflux carrier PIN1 at the plasma
membrane and are required for embryo development.
Spitzer, Christoph (a)
Welnak, Nicole K (a)
Sliwinski, Marek K (a)
Haas, Thomas J. (a)
Otegui, Marisa S.-presenter
[email protected](a)
The ESCRT machinery has emerged as an important cellular pathway required for endosomal sorting of endocytic and secretory proteins
targeted for degradation in the vacuole. The machinery itself has been characterized in fungi, animals and plants but targets have only been
identified in the first two kingdoms so far. The CHMP1A and B proteins are similar to mammalian CHMP1 and yeast Did2p which are
involved in the dissociation of ESCRT III complex from endosomal membranes. A double Arabidopsis chmp1a/b mutant is heavily retarded
in embryo development and dies shortly after germination. In this study we show that the Arabidopsis CHMP1 proteins are required for
embryonic axis formation and that the auxin efflux carrier PIN1 is a target of the Arabidopsis ESCRT pathway. The localization of PIN1
protein is crucial for defining the axis of the Arabidopsis embryo and the shift from radial to bilateral symmetry. In accordance with this, the
chmp1a/b mutant embryos develop into ball-like structures that either form no cotyledons at all or develop multiple cotyledons that in most
cases fail to expand. Whereas in wild type heart/torpedo embryos PIN1 is predominantly expressed in developing cotyledons and vascular
tissues, in the chmp1a/b mutant PIN1 is expressed throughout the embryo. On the cellular level we find that PIN1 protein fails to localize in
a polarized manner. PIN1:GFP signal mislocalizes to membrane structures of various sizes in the cytosol, including the central vacuole and
endosomes. PIN1 loaded bodies frequently accumulate close to the central vacuole and resemble Class E compartments found in yeast
ESCRT mutants. Interestingly PIN1 seems to accumulate in chmp1a/b mutant embryos compared to wild type indicating a failure to
efficiently degrade PIN1.
(a) University of Wisconsin-Madison
Date
SATURDAY
June 28
Start
3:00 PM
End
Minisymposium
4:40 PM Minisymposium 3 – Metabolism Trafficking – Chair:
Georg Jander
3:00 - M0301: Jennifer R. Watling - Hot plants: single power
Location
Siglo XXI Convention Center Salon Izamal
source, hybrid or turbo-charged?
3:25 - M0302: Alberto A. Iglesisas - Understanding the fate of
trioses-phosphate in plant cells. A study on the regulation of
cytosolic glyceraldehyde-3-phosphate dehydrogenases
3:50 - M0303: Mark A. Settles - Multiple non-redundant roles
for plastidic 6-phosphogluconate dehydrogenase in maize
4:15 - M0304: Georg Jander - Reduced activity of Arabidopsis
thaliana HMT2, a methionine biosynthetic enzyme, increases
seed methionine content
M0301 Hot plants: single power source, hybrid or turbo-charged?
Watling, Jennifer R.-presenter [email protected](a)
Grant, Nicole M (b,a)
Miller, Rebecca E (a,b)
Robinson, Sharon
A (b)
The thermogenic plant Philodendron selloum can regulate heat production, maintaining an inflorescence temperature of 38-46oC across air
temperatures of 4-39oC. Sterile male florets have been considered the principal source of heat, but our results indicate that fertile male
florets also heat. Thermoregulatory phases were identified in both floret types, and sterile males also have a thermogenic burst. The two
possible pathways for heat production in plants involve the alternative oxidase (AOX) and plant uncoupling proteins (pUCPs). We used
stable oxygen isotope measurements to quantify respiratory flux, along with protein and substrate determination to elucidate the
contribution of each pathway to heating in both floret types. Our results suggest a role for the AOX pathway in both floret types during
thermoregulatory phases. Whereas pUCP may play a greater role during the thermogenic burst where fluxes reached 0.087+0.019 μmol O2
g fw-1 s-1. Consistent with this was the observation that sterile males contained higher concentrations of lipids than fertile males, and the
concentration declined during the thermogenic phase. In contrast, starch concentrations were higher in fertile males, where the AOX
pathway was largely responsible for heat generation. Whilst both AOX and COX proteins were present in prethermogenic florets, they
increased significantly in both floret types with the onset of thermogenesis and AOX appears to be post-translationally regulated. In
contrast, pUCP protein has only been detected in sterile male florets. Our results suggest that both pUCP and AOX may operate together in
P. selloum, with AOX potentially involved in thermoregulation whilst pUCP could provide an additional boost during maximal heating.
(a) Earth & Environmental Sciences, University of Adelaide (b) Institute for Conservation Biology, University of Wollongong
M0302 Understanding the fate of trioses-phosphate in plant cells. A study on the regulation of cytosolic glyceraldehyde-3phosphate dehydrogenases
Iglesias, Alberto A-presenter [email protected](a)
Piattoni, Claudia V (a)
Guerrero, Sergio A (a)
Oxidation of glyceraldehyde-3P to 3P-glycerate in the cytosol of plant cells can follow two different pathways. One, involves phosphorylating
glyceraldehyde-3P dehydrogenase (Ga3PDHase, EC 1.2.1.12) and 3P-glycerate kinase. The other pathway occurs via non-phosphorylating
glyceraldehyde-3P dehydrogenase (npGa3PDHase; EC 1.2.1.9), an enzyme found in photosynthetic eukaryotes. In green cells,
npGa3PDHase is involved in a shuttle system to export chloroplastic NADPH. In non-green tissues, the role of the enzyme is less clear;
although it catalyzes a critical metabolic branch point in glycolysis, where trioses-P are derived to produce NADPH as an alternative to the
synthesis of ATP and NADH. We characterized the post-translational regulation of wheat npGa3PDHase by two mechanisms:
phosphorylation of serine residues and redox modification of cysteines. The recombinant enzyme was phosphorylated after incubation with
wheat endosperm extracts, under reaction conditions specific for SNF1-related protein kinases. The modification was inhibited by glucose6P, as was previously reported for protein kinases involved in regulation of carbon metabolism in plants. Phosphorylation was neither
observed by other plant protein kinases, nor by incubation with leaf extracts. Site directed mutagenesis studies showed that Ser-404 is the
amino acid residue phosphorylated in npGa3PDHase. These results agree with previous data showing that in heterotrophic plant cells the
enzyme exhibits distinctive regulatory properties associated with phosphorylation and interaction with 14-3-3 proteins. On the other hand,
53
npGa3PDHase from wheat was inactivated by thiol oxidants as diamide, hydrogen peroxide, sodium nitroprusiate, and oxidized gluthation.
The loss of activity was effectively reversed after incubation with dithiothreitol and reduced thioredoxin, thus suggesting that the process
could function physiologically. Ga3PDHase was markedly more sensitive to thiol oxidants (and also more resistant to reactivation by
reductants) than npGa3PDHase. It is tempting to speculate that under oxidative conditions in the cytosol of plant cells, the fate of trioses-P
is preferably derived to NADPH generation rather than to ATP. Results support a scenario where the oxidation of trioses-P is a key metabolic
point to regulate the carbon partitioning to produce redox or energy equivalents in the cytosol of plant cells. Work granted by CONICET,
ANPCyT and UNL (Argentina).
(a) Lab. Enzimologia Molecular. Fac. Bioquimica Cs. Biologicas. Universidad Nacional del Litoral
M0303 Multiple non-redundant roles for plastidic 6-phosphogluconate dehydrogenase in maize
Li, Li (a)
Roemisch-Margl, Lilla (b)
Spielbauer, Gertraud (a)
Tseung, Chi-Wah (a)
Gierl, Alfons (b)
Genschel, Ulrich
(b)
Settles, A. Mark-presenter [email protected](a)
http://www.hos.ufl.edu/amsweb/
The oxidative pentose phosphate pathway (OPPP) serves multiple roles in primary metabolism. Enzymes for the oxidative section of the
OPPP are found both in the cytosol and plastid. Several mutant studies have suggested that cytosolic and plastidic OPPP enzymes are
redundant with each other. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase (6PGDH) catalyze the three nonreversible steps of the oxidative section of the OPPP. 6PGDH enzymes are more tractable for genetic analysis because they comprise a
smaller gene family in plants. Maize mutations in the cytosolic 6PGDH enzymes, pgd1 and pgd2, do not show obvious phenotypes beyond
loss of enzyme activity. We identified two knockout alleles of the maize Pgd3 locus. pgd3 mutants disrupt plastid-localized 6PGDH activity
and cause a rough endosperm (rgh) phenotype that affects both grain-fill and embryo development. Consistent with the reduced grain-fill
phenotype, 13C-glucose labeling experiments during seed development suggest that pgd3 mutants disrupt carbohydrate flux for starch
synthesis. PGD1, PGD2, and PGD3 are all active in both the endosperm and embryo. These data suggest that plastid-localized 6PGDH has a
non-redundant role for seed development. Moreover, homozygous pgd3 mutants can be rescued through tissue culture. Mutant pgd3 plants
show normal morphology but are slow to green and late flowering. Interestingly, PGD3 activity is lower in green tissues suggesting that the
slow to green phenotype is due to disruptions in carbon metabolism during leaf expansion.
(a) University of Florida (b) Technische Universitaet Muenchen
M0304 Reduced activity of Arabidopsis thaliana HMT2, a methionine biosynthetic enzyme, increases seed methionine
content
Lee, Minsang (a)
Huang, Tengfang (a)
Toro-Ramos, Tatiana (a,d)
Fraga, Michel (b)
Last, Robert L (c,b)
Jander, Georgpresenter [email protected](a,b)
http://bti.cornell.edu/jander/
In the S-methylmethionine cycle of plants, homocysteine methyltransferase (HMT) catalyzes the formation of two molecules of methionine
from homocysteine and S-methylmethionine, and methionine methyltransferase (MMT) catalyzes the formation of methionine from Smethylmethionine using S-adenosylmethionine as a methyl group donor. Somewhat surprisingly, two independently isolated knock-down
mutations of HMT2 (At3g63250), one of three Arabidopsis thaliana genes encoding homocysteine methyltransferase, increased free
methionine accumulation in the seeds. Although methionine abundance is increased only in the seeds, S-methylmethionine levels increased
in both seeds and vegetative tissue. Crosses and flower stalk grafting experiments demonstrate that the maternal genotype at the top of
the flower stalk determines the seed S-methylmethionine and methionine phenotype of hmt2 mutants. Uptake, transport, and
interconversion of [13C]S-methylmethionine and [13C]methionine in hmt2, mmt, and wild-type plants show that S-methylmethionine is a nonessential intermediate in the movement of methionine from vegetative tissue to the seeds. Together, these results support a model whereby
excess S-methylmethionine in hmt2 vegetative tissue is transported to seeds and either directly or indirectly results in the biosynthesis of
additional methionine. Targeted manipulation of the S-methylmethionine cycle could be used to increase the nutritive value of crop plant
seeds.
(a) Boyce Thompson Institute for Plant Research (b) Cereon Genomics (c) Department of Biochemistry and Molecular Biology, Michigan
State University (d) Department of Nutritional Sciences, Rutgers University
Date
SATURDAY
June 28
Start
3:00 PM
End
Minisymposium
Location
4:40 PM Minisymposium 4 – Plant Pathogen Interactions – Chair: Siglo XXI Convention Center Hong Gu Kang
Salon Progreso
3:00 - M0401: Jagger JW Harvey - Biogenesis and function of
plant viral small RNAs
3:25 - M0402: Xiaohang Wang - Functional characterization of
CLE peptides from a plant-parasitic nematode, Globodera
rostochiensis
3:50 - M0403: Wei Ma - Cyclic nucleotides act as an early
signal upstream from Ca2+ in plant innate immunity
4:15 - M0404: Hong Gu Kang - CRT1, an Arabidopsis ATPase
that interacts with diverse resistance proteins and modulates
disease resistance to Turnip crinkle virus
M0401 Biogenesis and function of plant viral small RNAs
Harvey, Jagger JW-presenter [email protected](b,a)
Studholme, David (a)
MacLean, Dan (a)
Etherington, Graham
(c)
Baulcombe, David (b)
RNA silencing is a plant defence mechanism that targets genomes of invading viruses for degradation. Dicer-like enzymes process the viral
genome into 21-24nt small RNAs (sRNAs) that can affect expression of other genes via Watson-Crick base pairing. In response, viruses have
evolved to encode silencing suppressors as well as sRNA silencing effectors that turn host silencing to their advantage. This study uses
54
PB 2008
large-scale Illumina sequencing by synthesis to profile sRNAs at early timepoints of Turnip crinkle virus (TCV) infection in susceptible
Arabidopsis. These datasets are being used to identify virus and host sRNA origins and potential targets, differentially expressed virulenceor resistance-related sRNAs, and candidate host- and virus-encoded miRNA genes and prediction of their cognate targets. The sRNA profiles
are also being used for prediction of sRNA-mRNA gene regulation networks in healthy and infected plants. Additionally, viral sRNA hotspot
profiles in infected silencing mutants are being used to elucidate the RNA silencing genes involved in production of several viral sRNA
classes. Any susceptibility- or resistance-related sRNA generating loci or general biogenesis mechanisms identified by this study will shed
new light on the complex role of RNA silencing in plant-virus interactions and may reveal new strategies of engineering disease resistance.
(a) The Sainsbury Laboratory, Norwich UK (b) Dept . of Plant Sciences, University of Cambridge, UK (c) John Innes Centre, Norwich UK
M0402 Functional characterization of CLE peptides from a plant-parasitic nematode, Globodera rostochiensis
Lu, Shun-Wen (a)
Wang, Jianying (b)
Chen, Shiyan (a)
Yu, Hang (a)
Mitchum, Melissa G (b)
Wang, Xiaohong-presenter
[email protected](a,c)
Plant CLAVATA3/ESR (CLE) proteins are a large family of secreted peptide ligands that play important roles in plant growth and
development. Recent evidence suggests that plant-parasitic cyst nematodes secrete ligand mimics of plant CLE peptides to modify selected
host root cells into multinucleate feeding sites. Parasitism genes encoding for CLE-like peptides were cloned from the potato cyst nematode,
Globodera rostochiensis, and found to be expressed in the dorsal esophageal gland cell of the nematode during feeding site initiation and
maintenance. Gene structure analysis grouped Gr-CLE genes into two major classes, Gr-CLE-1 and Gr-CLE-4, in which Gr-CLE-4 was
confirmed to have multiple copies in the genome. Interestingly, unlike most plant CLEs and the nematode CLEs of the genus Heterodera,
members of the G. rostochiensis CLE peptide family were found to contain multiple CLE domains. Overexpression of either Gr-CLE-1 or GrCLE-4 in Arabidopsis under the control of the CaMV35S promoter produced phenotypes resembling those produced by plant CLEs including
wuschel-like seedlings, generation of wuschel flowers, short roots, anthocyanin accumulation, delayed development, and seedling death. In
vitro application of synthetic 12-amino acid peptides, corresponding to the CLE motifs of Gr-CLE-1 and Gr-CLE-4, to the roots of Arabidopsis,
tomato, and potato caused a short root phenotype. Transient expression of the full-length Gr-CLE-1 gene as a C-terminal tagged protein in
Nicotiana benthamiana leaves revealed that Gr-CLE-1 was processed into different forms of potentially membrane-bound proteins,
suggesting a possible proteolytic processing of the Gr-CLE-1 CLE domains in vivo. Our studies suggest that this novel class of nematode
CLEs has functional similarity to plant CLE signaling peptides and highlight an important role for ligand mimicry in plant parasitism by G.
rostochiensis.
(a) Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY (b) Division of Plant Sciences and Bond Life
Sciences Center, University of Missouri, Columbia, MO (c) Biological Integrated Pest Management Research Unit, USDA-ARS, Ithaca, NY,
USA
M0403 Cyclic nucleotides act as an early signal upstream from Ca2+ in plant innate immunity
Ma, Wei-presenter [email protected](a)
Smigel, Andries (a)
Verma, Rajeev (a)
Ali, Rashid (a)
Lemtiri-Chlieh, Fouad
(a)
Gehring, Chris A (b)
Pearce, Gregory (c)
Ryan, Clarence A (c)
Berkowitz, Gerald A (a)
Ca influx into cells is a critical early signal in plant innate immune responses leading to nitric oxide (NO) generation and hypersensitive
response (HR) to avirulent (avr) pathogens. Little is known about proteins that facilitate this cytosolic Ca elevation, or how nonself invader
recognition is transduced to altered Ca flux. Arabidopsis dnd1 plants have a loss-of-function mutation in a cell membrane cyclic nucleotide
gated channel (CNGC), lack cyclic nucleotide (cNMP)-activated inward Ca current, pathogen associated molecular pattern (PAMP) elicitor
lipopolysaccharide (LPS) -induced NO generation and HR to avr P. syringae tomato (Pst). We demonstrate CNGC involvement in Ca influx
during HR, and identify a critical step upstream from this inward Ca current as involving pathogen-induced rise in cNMP; this rise translates
pathogen/PAMP perception into a cytosolic signal leading to Ca influx through CNGCs and ownstream innate immunity signaling. Plant cell
cytosolic cAMP level is controlled by the integrated activities of adenylate cyclase (AC) (cAMP synthesis) and cAMP-phosphodiesterase (PDE)
(cAMP breakdown). AC inhibitor impairs LPS-induced NO generation in leaf guard cells, as well as Pst-induced cytosolic Ca elevation and HR.
PDE inhibitor has opposite effects, eliciting NO generation in the absence of LPS, and prolonging the Ca elevation and hastening HR to Pst.
Patch clamp analysis indicates LPS can activate inward Ca current, linking the perception of pathogen/PAMP to the activation of the Ca
channel. Importantly, Pst increased leaf [cAMP]; addition of PDE inhibitor with Pst further increased the [cAMP] spike. These results link
cNMP with this signal cascade. Bioinformatic approaches intriguingly identify a nucleotide cyclase domain in some leucine-rich-repeat
receptor like kinases (LRR-RLKs) including AtPepR1, the receptor for AtPep plant-derived ‗elicitor‘ peptides thought to be involved in innate
immunity signaling. Preliminary studies indicate AtPep induces cytosolic Ca elevation and AtPepR1 has nucleotide cyclase activity when
expressed in E. coli; suggesting that AtPepR1 may be a ‗sentry‘ receptor involved in initiating the signal cascade leading to innate immune
responses. Thus, we can present a new model linking several molecular events as involved in plant innate immunity signal perception and
transduction. Supported by NSF award 0721679.
(a) Department of Plant Science, University of Connecticut, Storrs, CT 06269-4163, USA (b) Department of Biotechnology, University of the
Western Cape, Bellville, South Africa (c) Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA
M0404 CRT1, an Arabidopsis ATPase that interacts with diverse resistance proteins and modulates disease resistance to
Turnip crinkle virus
Kang, Hong-Gu-presenter [email protected](a)
Kuhl, Joseph C (a,c)
Kachroo, Pradeep (b)
Klessig, Daniel F (a)
HRT is a CC-NBS-LRR-type resistance (R) protein that is required for resistance to turnip crinkle virus (TCV) in Arabidopsis. To gain insights
into HRT-mediated signaling, we used a genetic screen to identify mutants in which recognition of the TCV avirulence factor was
compromised. One mutant, crt1 (compromised recognition of TCV), carries a mutation that results in premature termination of a novel
ATPase protein that would otherwise contain a GHKL ATPase motif. Following TCV infection, crt1 developed a spreading hypersensitive
response and failed to prevent viral replication and spread, which were more pronounced when two closely related CRT1 homologs also
were partially silenced. crt1 also suppressed cell death induced by ssi4, a constitutively active TIR-NBS-LRR-type R protein, and by
Pseudomonas syringae carrying avrRpt2. CRT1 interacts with the NBS domain of HRT. In addition, CRT1 also interacts with SSI4, and two
other R proteins, RPS2 and Rx. Interestingly, ssi4-induced cell death was suppressed by some of the truncated CRT1 variants, perhaps by
disrupting interaction between the activated R protein and wild type CRT1. Taken together, the results argue that CRT1 is a novel and
important player in R gene-mediated signaling.
55
(a) Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA (b) Department of Plant Pathology, University of Kentucky,
Lexington, KY 40546, USA (c) U.S. Department of Agriculture, Agricultural Research Service, Palmer, AK 99645, USA
Date
SATURDAY
June 28
Start
3:00 PM
End
Minisymposium
4:40 PM Minisymposium 5 – Root Biology – Chair: Joseph G.
Dubrovsky
3:00 - M0501: Joseph G. Dubrovsky - Root system formation:
Location
Siglo XXI Convention Center Salon Ekbalam
how lateral root initiation is related to the number of cells
between successive primordia
3:25 - M0502: Jose Efrain Ramirez Benite - Root transition
zone is the primary site of copper-induced oxidative stress
3:50 - M0503: Rosangela Sozzani - Radial Patterning in the
Arabidopsis root: Exploring for new SHR target genes
4:15 - M0504: Jianbo Shen - Auxin mediates patterning of
cluster root development induced by phosphorus deficiency in
Lupinus albus
M0501 Root system formation: how lateral root initiation is related to the number of cells between successive primordia
Dubrovsky, Joseph G.-presenter [email protected](a)
Soukup, Ales (a,b)
Napsucialy-Mendivil, Selene (a)
Ivanchenko, Maria G.
(c)
Initiation of lateral roots is a cardinal point in root system formation. In Arabidopsis, new primordia are initiated in a relatively narrow
developmental window in a strictly acropetal pattern (Dubrovsky et al., 2006, Ann Bot, 97: 903-915). In this study we analyze how lateral
root initiation is related to the number of elongated cells in a cell file produced by the root apical meristem. We propose a lateral root
initiation index (ILRI) as an integrative parameter that establishes how many initiation events took place in a portion of the parent root that
corresponds to a defined number of cells in a file along the same root portion. To show how useful ILRI is in understanding lateral root
formation, we compare it in four Arabidopsis accessions grown under the same conditions, between plants grown on media with different
C:N ratio, in plants treated with ethylene precursor ACC, in mutants affected in lateral root formation and in different species grown under
the same conditions. Our data indicate that ILRI permits to more precisely evaluate lateral root formation in regard to growth conditions or in
plants of different genetic background. ILRI apparently reflects how nutrients are allocated at the cellular level and how this allocation is
involved in regulation of morphogenesis and root system architecture. Thus, ILRI is more informative then the commonly used parameter of
lateral root (or primordium) density, which is estimated based simply on root length. This matter will be discussed. The work was supported
by DGAPA, UNAM (IN225906) and CONACyT (49267).
(a) Departamento de Biologia Molecular de Plantas, Instituto de Biotecnologia UNAM (b) Department of Plant Physiology, Charles University
(c) Department of Botany and Plant Pathology, Oregon State University
M0502 Root transition zone is the primary site of copper-induced oxidative stress
Madejon, Paula (b)
Ramirez, Jose Efrain-presenter [email protected](c)
Corrales, Isabel (a)
Poschenrieder, Charlotte
(a)
Barcelo Coll, Juan (a)
Root sensing of toxic conditions is essential for activation of defense mechanisms and plant survival in problem soils. The transition zone
where root cells exit division phase and prepare for fast expansion has been identified as the site of perception of Al toxicity. This study
reveals that the transition zone is also the primary site of Cu-induced oxidative stress. Two maize varieties (var. Orense, Cu-sensitive and
Oropesa, Cu tolerant) were exposed in hydroponics for 24 h to Cu ranging from 0.25 to 10 μM. Fluorescence microscopy revealed oxidative
damage that initially was restricted to the transition zone at 1 to 2 mm from tip. Thresholds for Cu toxicity assessed by root elongation
essay were 2 and 5 μM Cu for varieties Orense and Oropesa, respectively. Higher Cu tolerance in variety Oropesa seemed not due to better
Cu exclusion from entire roots, but to a specific enhancement of Cu/Zn-SOD activity in the 0 to 5 mm root apex. Moreover, the root tips of
the Cu tolerant variety produced more border cells than those of Cu sensitive maize variety. Our results show that the root transition zone is
the primary site for sensing of Cu toxicity in maize. A high rate of root tip cell turnover and more efficient detoxification of superoxide
anions by a local enhancement of SOD in the root tips seem essential for the better Cu tolerance in maize variety Oropesa. Financial
supports from the Spanish Government DGICYT PBBFU2007-60332/BFI and from CONACyT (grant No C45798-Z) from Mexican Government
are acknowledged.
(a) Lab. Fisiologia Vegetal, Facultad Biociencias Universidad Autonoma de Barcelona, Bellaterra, Spain (b) Instituto de Recursos Naturales y
Agrobiologia de Sevilla (IRNAS), CSIC, Spain (c) Unidad de Bioquimica y Biologia Molecular de Plantas, Centro de Investigacion Cientifica de
Yucatan, Merida, Mexico
M0503 Radial Patterning in the Arabidopsis root: Exploring for new SHR target genes
Sozzani, Rosangela-presenter [email protected](a)
Jose, Dinneny R (a)
Siobhan, Brady M (a)
Hongchang, Cui (a)
Yueling, Hao
(a)
Philip, Benfey N (a)
Arabidopsis roots are a model system for investigating the molecular basis of cell patterning and development. The combinatorial activity of
two transcription factors, SHORT-ROOT (SHR) and SCARCROW (SCR), is necessary for the radial patterning of the post-embryonic root. SHR
directly regulates SCR and together they promote the asymmetric division of the cortex/endodermal initials to generate the ground tissue
layers. In order to develop an exhaustive model of SHR-mediated signaling in root radial pattering, we are using a conditional activation
system. To identify both early SHR downstream genes and genes involved in the asymmetric division, we utilized cell-sorting technology to
specifically examine the transcriptional effects of SHR induction on ground tissue cell layers. We combined SHR-induction in a time course
with the analysis of gene expression profiles in a microarray experiment. Analysis of Gene Ontology category enrichment was used to
identify important biological processes regulated by SHR. Groups of co-expressed genes were identified and the expression profiles were
analyzed using the high-resolution expression map previously developed for the Arabidopsis root. Using the SCR::GFP marker line we
observed that at 3 hours after SHR induction, SCR::GFP expression is already detectable, suggesting that SHR target genes are expressed
56
PB 2008
already at 3 hours. In order to identify other early target genes, we are examining the function of genes sets whose expression changes at
1 hour following SHR induction. Of the genes we identified as SHR-targets, several exhibit the same expression pattern of well known target
genes. Further experiments will be done in order to determine if SHR directly regulates these candidate target genes.
(a) Duke University
M0504 Auxin mediates patterning of cluster root development induced by phosphorus deficiency in Lupinus albus
Shen, Jianbo-presenter [email protected](a,b)
Cheng, Lingyun (a,b)
Liu, Junqi (b)
Zhang, Fusuo (a)
Allan, Deborah A
(c)
Culler, Angela (d)
Cohen, Jerry (d)
Vance, Carroll P (e,b)
White lupin (Lupinus albus L.) develops cluster roots under phosphorus (P) deficiency. This species is widely used as a model system to
study the morphology and physiology of cluster roots. However, the mechanism of P deficiency-induced cluster root formation is not fully
understood. To evaluate the contributions of auxin to cluster root formation, we examined the gradient of IAA concentration, expression of
IAA reporter DR5-GUS, and expression of LaIAA14 and auxin influx at 5 different developing stages of cluster root formation, including root
tips, meristem initiation, initiated but not emerged, juvenile and mature cluster roots. Phosphorus deficiency significantly increased the IAA
concentrations in the cluster root segment at initiation stage before emergence. Higher IAA concentrations were found in root segments at
cluster-root initiation stages under P deficiency, but there was no significant difference in IAA concentrations in root segments receiving
normal P supply. The number of emerged rootlets or meristems before emergence in the P-deficiency plants was significantly greater than
in the P-adequate plants. LaIAA14 was expressed at all stages of cluster root formation; high expression was found at root tips and juvenile
stage but the expression was highly repressed at initiation stage. In contrast, the high expression of auxin influx was concentrated in root
tips and meristem initiation, but not in the mature cluster roots, indicating an early signal sensing. The results reflect auxin involvement in
cluster root development induced by P deficiency in Lupinus albus.
(a) Department of Plant Nutrition, Laboratory of Plant-Soil Interaction, China Agricultural University, Beijing, 100094, P.R. China (b)
Department of Agronomy and Plant Genetics, University of Minnesota (c) Department of Soil, Water and Climate, University of Minnesota
(d) Department of Horticultural Science, University of Minnesota (e) USDA-ARS, Plant Science Research
Date
SATURDAY
June 28
Start
5:10 PM
End
Minisymposium
Location
6:50 PM Minisymposium 6 - Minority Affairs Symposium – Chair: Salon Merida
MaryElena Zavala
5:10 - M0601: Eleanore Wurtzel - Maize: a model cereal crop
for developing strategies to solve global vitamin A deficiency
5:35 - M0602: Netali Ochoa Alejo - Chili pepper: Biotechnology
of a historically and culturally important crop for Mexicans
6:00 - M0603: Elisa Leyva-Guerreo - Vacuolar expression of
linamarase in cassava roots increases root free amino acids and
leaf protein
6:25 - M0604: Alejandra Jaramillo - Piperales: Spices, medicine
and models
M0601 Maize: a model cereal crop for developing strategies to solve global vitamin A deficiency
Wurtzel, Eleanore T-presenter [email protected](a,b)
Vallabhaneni, Ratnakar (a,b)
Li, Faqiang (a,b)
Quinlan, Rena
(a,b)
http://maize.lehman.cuny.edu/webwurtzel/wurtzelhomepage/wurtzel.html
Global vitamin A deficiency is linked to diets deficient in pro-vitamin A carotenoids. One approach to alleviating this deficiency is to enhance
pro-vitamin A carotenoid content in endosperm of crops such as maize, sorghum, and wheat, related grasses in the Poaceae (Grass family)
and important food staples worldwide. However, such efforts are predicated on understanding regulation of carotenogenesis which is
localized in plastids and mediated by nuclear-encoded enzymes. This regulation is compounded by the complexity of carotenoid function
which includes roles in photosynthesis, photoprotection, development, and abiotic and biotic stress tolerance. Therefore, having potential to
impact plant yield and nutritional quality, carotenoids are key targets for metabolic breeding/engineering. Maize is an attractive model
system for elucidating the regulation of endosperm carotenogenesis because of its associated genetic and genomic resources. Maize
resources include a diverse germplasm collection exhibiting genetic and chemical variation that can be used to discover rate-controlling
steps in the pathway and to identify useful breeding alleles. Using traditional gene cloning, bioinformatics and syntenic comparisons with
other grasses, we found that many of the biosynthetic enzymes are encoded by small gene families, unlike the case in a simpler model
plant, Arabidopsis. These gene family members appear to have specific roles in different tissues and in response to unique signals. Our goal
has been to identify those gene family members that specifically impact endosperm carotenoid content and composition. Our analysis of
maize mutants led to discovery of a new carotenoid biosynthetic step that is essential in all higher plant carotenoid biosynthesis. We
conducted transcript profiling of the maize germplasm diversity collection and identified gene family members that specifically impact
provitamin A carotenoid content. These findings are leading to development of breeding alleles for improvement of maize endosperm
carotenoids; further translation of these findings to other grasses is facilitated by phylogenetic identification of orthologous genes that may
serve as potential targets for enhancement of carotenoid content.
(a) Dept. of Biological Sciences, Lehman College, The City University of New York, USA (b) Graduate School, The City University of New
York, USA
M0602 Chili pepper: Biotechnology of a historically and culturally important crop for Mexicans
Ochoa-Alejo, N.-presenter [email protected](a)
Herrera-Isidron, L. (a)
Aza-Gonzalez, C. (a)
Nunez-Palenius, H.G.
(a)
Lozoya-Gloria, E. (a)
Martinez-de-la-Vega, O. (a)
Rivera-Bustamante, R.F. (a)
Chili pepper is a very important horticultural crop worldwide. Mexico is believed to be the domestication center of Capsicum annuum L., and
produces a great variety of chili peppers. Mexico is currently the third world chili pepper producer. We have focused our work mainly on the
development of different plant cell, tissue and organ culture systems and also on the establishment of in vitro plant regeneration and
57
Agrobacterium-mediated transformation protocols in order to carry out basic studies and also as biotechnological tools. We have established
the conditions for in vitro chili pepper plant regeneration from different explants sources and also from anther cultures. Cell and callus
cultures have been used in our laboratory to study the production of capsaicinoids, the hot principle of Capsicum fruits, and also for the
isolation of cell lines resistant to drought. Three years ago we started a project on chili pepper transcriptomics with the aim of isolating and
characterizing cDNA sequences of genes involved in the biosynthesis of compounds that are synthesized and accumulated in chili pepper
fruits, including capsaicinoides, anthocyanins, carotenoids and ascorbic acid, among others. cDNA libraries or subtractive cDNA libraries
were generated from pericarp or placenta tissues producing those metabolites. A total of approximately 14,000 sequences were generated.
More recently, a Cinvestav-group project on basal transcriptomics of chili pepper was established to investigate genes that are expressed in
roots, stems, leaves, flowers and fruits of a Serrano-type chili pepper (Tampiqueno 74) grown under controlled conditions. As a result,
nearly 45,000 cDNA sequences were generated that are currently under analysis and functional annotation. In order to study gene function,
a virus-induced gene silencing protocol has been used in our laboratory. All this knowledge is expected to be used for genetic engineering
and genetic improvement of chili pepper in the near future.
(a) Cinvestav Campus Guanajuato
M0603 Vacuolar expression of linamarase in cassava roots increases root free amino acids and leaf protein
Leyva-Guerrero, Elisa-presenter [email protected](a)
Sayre, Richard T (a)
Cassava roots are a staple food in Sub-Saharan Africa. A cassava-based diet however, is deficient in protein and has the additional risk of
cyanide exposure from poorly processed cassava. The cyanogenic glycoside, linamarin, is synthesized in the leaves of cassava and
transported symplastically to the roots where it is stored in the vacuole. Upon cell rupture the enzyme linamarase, which is localized to the
cell wall and laticifers, deglycosilates linamarin, yielding acetone cyanohydrin, which can degrade to produce cyanide. Recent evidence
indicates that linamarin may be a major transportable form of reduced nitrogen from leaves to roots and that the linamarin nitrile group can
be assimilated into free amino acids via the β-cyanoalanine synthase pathway. We hypothesized that we could accelerate the linamarin
deglycosylation and cyanide assimilation into amino acids by overexpressing linamarase in the vacuole of root cells. Two independent
transgenic cassava lines expressing a root, vacuolar-targeted linamarase had a 50% to 76% increase in total root free amino acids and a
slight overall reduction in linamarin content. Interestingly, there was no increase in root protein content. On the other hand we observed a
10 to 16% increase in leaf soluble protein levels. These results suggest that root free amino acids are transported to the leaf (nitrogen sink)
for protein synthesis. Interestingly the transgenic lines show a marked decrease in leaf linamarin content, presumably associated with the
greater linamarin sink strength and flux to roots. Currently we are working on expressing the vacuolar targeted linamarase coordinately with
gene encoding root storage proteins to capture the additional root free amino acids in the roots.
(a) The Ohio State University
M0604 Piperales: Spices, medicine and models
Jaramillo, Alejandra-presenter [email protected](a)
The Piperales are used as spices, medicine and various indigenous rituals. The best-known spice is black-pepper, Piper nigrum , a species of
Asian origin partly responsible, for the arrival of the Europeans to America. The Piperales are a basal lineage of angiosperms, that includes
the families Piperaceae, Saururaceae, and Aristolochiaceae. The first two have perianthless (with no petals or sepals) flowers, while
members of Aristolochaiceae exhibit a well-developed perianth. Furthermore, members of this order exhibit a large array of growth habits,
floral morphologies, and leaf shapes. Despite the variation in growth habits members of the Piperales are mostly herbaceous, especially
when compared to other early diverging lineages of flowering plants that are mostly trees. Because of their phylogenetic relationships
(among the early diverging lineages of angiosperms), the varied morphology and ecology, and herbaceous nature, the Piperales offer
unique opportunities to study the evolution of plant morphological traits, the processes of tropical diversification, as well as develop new
insecticides and medicine. In this talk I would like to tell you more about this fascinating group, in particular I will emphasize on the
potential of Aristolochia fimbriata as a new model organism to answer questions about the evolution of flowers, and other traits such as
climbing habit, flower color, and secondary compunds. We are conducting research on the development of flowers in A. fimbriata.
Aristolochia has a unipartite perianth that developmentally corresponds to the first whorl of organs. Despite its sepaloid origin Aristolochia‗s
perianth has a petaloid appearance with bright colors, and a smooth epidermis. We are evaluating the role of the petal and stamen identity
program in the production of the petaloid perianth of Aristolochia.
(a) University of Missouri-Columbia
Date
SATURDAY
June 28
Start
5:10 PM
End
Minisymposium
Location
6:50 PM Minisymposium 7 – Protein Modification and Turnover – Siglo XXI Convention Center Chair: Shaul Yalovsky
Salon Valladolid
5:10 – Abstract 0701: Miguel E. Vega Sanchez - The rice E3
ligase SPL11 ubiquitinates SPIN1, an RNA/DNA binding protein
involved in negative control of flowering time
5:35 – Abstract 0702: Shaul Yalovsky - Signaling by type-I
ROP/RAC GTPases requires transient acylation and
consequential partitioning into lipid rafts
6:00 – Abstract 0703: Maria Ek-Ramos - Subcellular localization
dynamics of two cell death regulating protein kinases in tomato
6:25 – Abstract 00704: Peter Geigenberger - Redox-regulation
of carbon storage in plants
M0701 The rice E3 ligase SPL11 ubiquitinates SPIN1, an RNA/DNA binding protein involved in negative control of flowering
time
Vega-Sanchez, Miguel E-presenter [email protected](a)
Zeng, Lirong (b)
Chen, Songbiao (a)
Leung, Hei (c)
Wang, GuoLiang (a)
58
PB 2008
The Spl11 gene was previously characterized as a negative regulator of both programmed cell death and broad-spectrum disease resistance
in rice. SPL11 encodes an Ubox/ARM repeat protein that has E3 ligase activity in vitro, suggesting its putative role in the
ubiquitination/protein degradation machinery, or other ubiquitin-mediated pathway. We show here that SPL11 also controls flowering via its
association with a novel protein of the Signal Transduction and Activation of RNA (STAR) family we have named SPIN1 (SPL11 interacting
protein 1). SPIN1 localizes in the nucleus of rice cells where it interacts with SPL11. SPIN1 binds both RNA and DNA in vitro, which suggests
a role in nucleic acid metabolism. Interestingly, neither silencing nor over-expression of Spin1 in transgenic plants causes cell death or
enhanced disease resistance, both typical phenotypes of the spl11 mutant. However, we observed that mutation of Spl11 causes delayed
flowering under non-inductive, long day conditions, while Spin1 over-expression causes late flowering independently of day length.
Expression analyses of flowering regulator genes showed that SPIN1 may function as a floral repressor by downregulating the expression of
the flowering promoter gene Hd3a via Hd1-dependent and independent mechanisms in short and long days, respectively. Moreover, we
show that SPIN1 is ubiquitinated by SPL11 but is not targeted for degradation. Our data is consistent with a model in which SPIN1 acts as a
negative regulator of flowering, itself negatively regulated by SPL11 via ubiquitination. This is the first evidence linking ubiquitination and
RNA metabolism in flowering time control in plants.
(a) Ohio State University, Department of Plant Pathology (b) Boyce Thompson Institute (c) International Rice Research Institute
M0702 Signaling by type-I ROP/RAC GTPases requires transient acylation and consequential partitioning into lipid rafts
Yalovsky, Shaul-presenter [email protected](a)
Sorek, Nadav (a)
Polarity is fundamental to cell form, differentiation and pattern formation. In plants, ROP/RAC GTPases function as master regulators of cell
polarity regulating the actin and microtubule cytoskeleton, cytoplasmic Ca 2+ influx NADPH oxidase vesicle trafficking and gene expression.
ROPs/RACs localize in a polar fashion and thereby determine the direction of cell growth and division. The mechanisms that regulate the
subcellular localization of ROPs/RACs and how they in turn affect signaling are not well understood. Previously, we showed that ROPs/RACs
are dually lipidated by geranylgeranyl isoprenyl and palmitic and stearic acids acyl moieties. In the present study we combined genetic
analysis, life cell imaging, FRAP, biochemical fractionation, tissue immuno-localization and GC/MS to determine the role of each of these
lipid modifications. In geranylgeranyl transferase-I deficient Arabidopsis background ROPs are farnesylated and acylated but their
association with the plasma membrane is unstable. Nevertheless, activated ROP/RAC forms could still induce changes in cell polarity. In
contrast, constitutive active non-acylated ROP/RAC mutants were not functional although they were stably associated with the plasma
membrane by virtue of their geranylgeranylation. These data imply that type-I ROPS/RACs must partition into discrete membrane domains,
known as lipid rafts, for signaling. Contrary to common belief the data show that acylation is required for signaling rather than for stable
membrane association. The different affects of geranylgeranylation and farnesylation on membrane association of ROPs may explain why
these two prenyl lipid modification have been conserved throughout evolution in eukaryotes.
(a) Tel Aviv University
M0703 Subcellular localization dynamics of two cell death regulating protein kinases in tomato
Ek Ramos, Maria J-presenter [email protected](a)
Coble, Kate A (a)
Devarenne, Timothy P (a)
Adi3 is a protein kinase regulated by Pdk1, a well known master regulator of the AGC kinase family which regulate critical processes such as
cell growth, differentiation and cell survival. In tomato, Adi3 and Pdk1 function as negative regulators of programmed cell death (PCD).
Here we show the localization dynamics of these protein kinases in tomato protoplasts, using wild type and mutant GFP fusion proteins
visualized by confocal microscopy. Adi3 is localized to the plasma membrane and nucleus, whereas Pdk1 is mainly found in plasma
membrane and cytoplasm. The constitutively active form of Pdk1, Pdk1T215D, is localized to the plasma membrane, nucleus and cytoplasm
while inactive Pdk1, Pdk1T215A, is detected in the nucleus. Constitutively active Adi3, Adi3S539D, is located to the plasma membrane, nucleus
and cytoplasm, while the inactive form, Adi3K337Q, is localized to the nucleus. Taken together the results suggest that activation of Pdk1 by
T215 phosphorylation allows Pdk1 to activate substrates such as Adi3. This activation of Adi3 (S359 phosphorylation) promotes Adi3
movement to the cytoplasm. Pdk1 also has a PH domain in the C-terminal that is important for plasma membrane localization since the
deleted mutant version is localized mostly to the cytoplasm. In addition, several plant AGC kinases have an extension of the catalytic loop
(T-Loop) which contains cellular localization signals. The Adi3 T-loop extension appears to contain a nuclear localization signal since deletion
of it shows non nuclear localization. Phosphatidic acid (PA) is a second messenger that acts as a known activator of Pdk1. Treatment of
tomato protoplasts with exogenous PA highly induced the localization of Pdk1 to the plasma membrane and Adi3 mobilization from plasma
membrane to nucleus. Interestingly, PA treatment localized Adi3 to structures consistent with the cytoskeleton. It indicates the response to
PA is mediated by Pdk1-activation of Adi3 in the plasma membrane and mobilization to the nucleus. It is supported by the fact that Adi3 TLoop-deleted mutant can not be phosphorylated by Pdk1, is not localized to the nucleus and does not respond to PA treatment . In
conclusion, our results indicate compartmentalization is very important for regulating the function of both proteins during PCD.
(a) Department of Biochemistry and Biophysics Texas A & M University
M0704 Redox-regulation of carbon storage in plants
Geigenberger, Peter-presenter [email protected](a,b)
Michalska, Justyna (a)
Kolbe , Anna (a)
Tiessen, Axel
(a,c)
Stitt, Mark (a)
Lunn, John E (a)
Hendriks, Janneke HM (a)
Oliver, Sandra N (a)
Starch is the major carbon store in plants. ADPGlc pyrophosphorylase (AGPase) catalyzing the rate-limiting step in the pathway of starch
synthesis in the plastid is exquisitely sensitive to allosteric regulation, which allows starch synthesis to be regulated by changes in
metabolite levels. In this presentation, I shall discuss more recent findings showing AGPase to be subject to a novel redox-based posttranslational regulation mechanism, which allows the rate of starch synthesis to be increased in response to external inputs and
independently of changes in phosphorylated intermediates (Tiessen et al. Plant Cell 14, 2191-2213; Hendriks et al. Plant Physiol 133, 838849). AGPase is rapidly redox-activated upon illumination by reduction of an intermolecular disulfide-bond between cysteines on the two
small subunits of the tetrameric enzyme. This resembles the light-activation of enzymes of the Calvin cycle, where electrons are transferred
from PS I to thioredoxins, which activate target enzymes by reduction of regulatory disulfides. Redox-activation of AGPase is also promoted
by sugars, which act additively with light, and also on their own in darkened leaves and in non-photosynthetic tissues. Recent studies
identified SNF1 related protein kinase (Tiessen et al. Plant J 35, 490-500) and trehalose-6-phosphate (Kolbe et al. PNAS 102, 11118-11123;
Lunn et al. Biochem J 397, 139-148) as signalling components linking redox-activation of AGPase to the availability of sugars in the cytosol.
Work is in progress to elucidate these signalling pathways. Specifically it will be investigated (i) how trehalose-6-phosphate enters the
59
plastid, (ii) by what mechanisms it promotes thioredoxin-dependent redox-activation of AGPase, and (iii) whether there are analogous
plastid targets.
(a) Max-Planck-Institute of Molecular Plant Physiology (b) Leibniz-Institute of Vegetable and Ornamental Crops (c) CINVESTAV Campus
Guanajuato
Date
SATURDAY
June 28
Start
5:10 PM
End
Minisymposium
Location
6:50 PM Mini-Symposium 8 – Intracellular Signaling – Chair: Alan Siglo XXI Convention Center Jones
Salon Izamal
5:10 - M0801: Peter Geigenberger - Acclimatory sensing of the
carbon status
5:35 - M0802: Elena Baena-Gonzalez - Arabidopsis KIN10 and
KIN11 are central mediators of convergent transcriptional
responses in energy and stress signaling
6:00 - M0803: Su-May Yu - Distinct Hexokinases (HXKs) Act as
Positive or Negative Regulators in the Sugar Signaling Pathway
6:25 - M0804: Alan Jones - Heterotrimeric G protein coupled Dglucose Signaling in Arabidopsis
M0801 Acclimatory sensing of the carbon status
Stitt, Mark (a)
Bjoern, Usadel (a)
Yves, Gibon (a)
Sulpice, Ronan (a)
Lunn, John (a)
Piques, Maria (a)
Pyl, Eva
(a)
Geigenberger, Peter-presenter [email protected](a)
Plants alternate between a positive C balance in the light and a negative C balance in the dark. This is buffered by accumulating starch in
the light, and remobilising it at night. Metabolism is regulated such that a small amount of starch remains at the end of the night. This is
achieved via acclimatory signalling pathways, which sense small changes of C and act to readjust C allocation and use before C becomes
acutely limiting. (1) C-deprivation rapidly inhibits biosynthesis and growth. After this happens, there is a delay before growth starts again
when C becomes available again. (2) There are coordinated changes of hundreds of transcripts during the night and first hrs of an extended
night. Genes for biosynthesis and cellular growth are repressed, while genes for catabolism are activated. This is driven by low, rather than
high, C and occurs before C becomes acutely limiting. (3) There are strong interactions between C-signalling and clock- and light-signalling,
which accentuate responses to C and attenuate responses to light during diurnal cycles. A simple linear model was developed, in which
information about the response to C, light and the clock is used to predict the global transcriptional responses in diurnal cycles. (4) Tre6P is
a C-signalling metabolite. It shows a highly amplified response when the C-status is perturbed during diurnal cycles, and acts to promote
thioredoxin-dependent activation of ADP-glucose pyrophosphorylase. (5) Comparison of the temporal kinetics of changes of transcripts,
enzymes and metabolites led to the concept that diurnal changes of transcripts are often integrated over days as changes of enzyme
activities and metabolism. This allows gradual adjustment to mid-term changes in the environment.
(a) Max Planck Institute of Molecular Plant Biology
M0802 Arabidopsis KIN10 and KIN11 are central mediators of convergent transcriptional responses in energy and stress
signaling
Baena-Gonzalez, Elena-presenter [email protected](a,b)
Rolland, Filip (c)
Sheen, Jen (a,b)
http://genetics.mgh.harvard.edu/sheenweb/
Controlling energy homeostasis is vital to plant growth and survival, and a rapid inhibition of growth is triggered even by short periods of
sugar starvation. Such starvation can be the result of reduced respiratory and/or photosynthetic activities that often accompany
environmental fluctuations. We and others have uncovered that different stress conditions induce similar alterations in carbon and nitrogen
metabolism, and lead to overlapping patterns of gene expression, with many genes being induced or repressed by multiple stimuli. Although
some of the stress-signaling cascades have been dissected in detail, their intersection points as well as the identity of the signaling
intermediates and key regulators remain largely unknown. Using a novel combination of cellular and systems approaches, we have
identified Arabidopsis KIN10 and KIN11 as central regulators of the energy signaling cascade that integrates seemingly unrelated darkness,
stress and carbon starvation conditions. Sensing and signaling stress-associated energy deprivation, these protein kinases (PKs) trigger
global gene expression reprogramming, implementing an energy-saving program that promotes catabolism and autophagy, and suppresses
anabolism and ribosome biogenesis. Significantly, KIN10/11 also target a plethora of transcription and signaling regulators to orchestrate
global responses beyond metabolic regulation. In support of this view, gain- and loss-of-function mutants display a wide range of
developmental alterations, suggesting that the role of these PKs might not be the mere adjustment of metabolism. Their actions are finely
integrated with other physiological and developmental cues in order to modulate plant growth and development in accordance to the
prevailing environmental conditions.
(a) Department of Molecular Biology, Massachusetts General Hospital, Boston MA, USA (b) Department of Genetics, Harvard Medical School,
Boston MA, USA (c) Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, K.U.Leuven, Belgium
M0803 Distinct Hexokinases (HXKs) Act as Positive or Negative Regulators in the Sugar Signaling Pathway
Yu, Su-May-presenter [email protected](a)
Chiang, Chih-Ming (a)
Studies from Arabidopsis indicate that HXK has dual roles in glucose phosphorylation and glucose signaling that control plant growth and
development. Studies from several plant species also indicate that HXK activities are associated with various cellular compartments,
suggesting the pleiotropic roles of HXKs in regulation of cellular biochemical processes. However, the identity of essential components
linking HXKs in the sugar signaling pathway, the detailed mechanisms underlying HXK-regulated gene expression, and how they control
plant growth and development remain mostly unclear. HXKs are encoded by only 2 genes in yeast and 6 genes in Arabidopsis, but 11 genes
in rice. To understand the function of individual HXK, and the mechanism linking HXKs with other components in the sugar signaling
pathway, we characterized the rice HXK family. Rice α-amylase genes are known to be feedback-regulated by sugars. By rice embryo gainand loss-of-function transient expression assays, we found that the rice HXK family could be classified into three groups, with two of them
60
PB 2008
playing positive or negative regulatory role upstream of the SNF1 related protein kianse (SnRK1A), the MYB transcription factor (MYBS1)
and α-amylase genes in the sugar signaling pathway. Further studies with transgenic approaches, by overexpression and knockdown
expression of positive and negative HXKs, respectively, led to glucose insensitivity of α-amylase expression in rice embryos. We also showed
that individual HXKs play distinct roles regulating rice seed germination and seedling growth. Currently, cellular localizations of individual
HXKs fused to GFP are in progress, aiming at understanding whether the function and activity of HXKs are cellular compartment-dependent
and sugar-regulated.
(a) Academia Sinica
M0804 Heterotrimeric G protein coupled D-glucose Signaling in Arabidopsis
Jones, Alan M-presenter [email protected](a)
Adaptation to changes in sugar availability is critical for most organisms. Plants use sugars as signaling molecules and possess mechanisms
to detect and respond to changes in sugar availability, ranging from the level secondary signaling molecules to altered gene transcription.
Heterotrimeric G-protein coupled pathways are involved in sugar signaling in plants, and G-protein mutants display sugar-related
phenotypes. Regulator of G Signaling (RGS) proteins turn off signaling by accelerating the intrinisic GTPase activity of the Gα subunits of the
heterotrimeric G-protein complex. The Arabidopsis thaliana Regulator of G-protein Signaling protein 1 (AtRGS1) combines a receptor-like
seven transmembrane domain with an RGS domain. AtRGS1 interacts with the Arabidopsis Gα subunit (AtGPA1) of the heterotrimeric G
protein complex in a D-glucose-dependent manner and stimulates AtGPA1 GTPase activity. Furthermore, AtRGS1 regulates the activation of
AtGPA1 in a D-glucose-dependent manner. Thus, AtRGS1 is a D-glucose receptor GTPase Accelerating Protein (GAP), defining the prototype
for this new receptor class. It is well-known that D-glucose controls the rate of cell proliferation in meristems. Evidence is provided to show
that the mechanism of this glucose control is through regulation of the activation state of AtGPA1 through D-glucose control of GAP activity
of AtRGS1.
(a) Departments of Biology and Pharmacology, University of North Carolina, Chapel Hill, NC 27599
Date
SATURDAY
June 28
Start
End
5:10 PM
Minisymposium
Location
6:50 PM Minisymposium 9 – Peptide Signaling – Chair: David Craik Siglo XXI Convention Center 5:10 - M0901: David Craik - Discovery and Applications of the Salon Progreso
Cyclotides: Circular Knotted Plant Proteins
5:35 - M0902: Erik A. Schmetz - Specialist herbivore evasion of
plant defense elicitation: Engineered cATPC as a strategy to
recover cowpea (Vigna unguiculata) recognition and defense
against velvetbean caterpillars (Anticarsia gemmatalis).
6:00 - M0903: Alisa Huffaker - PROPEP Family Regulation of
Pathogen Defense in Arabidopsis thaliana
6:25 - M0904: Renu Srivastava - Proteolytic processing of a
plant peptide hormone by a subtilase in Arabidopsis
M0901 Discovery and Applications of the Cyclotides: Circular Knotted Plant Proteins
Craik, David J-presenter [email protected](a)
The cyclotides [1] are a recently discovered family of plant-derived proteins that have applications in drug design [2] and agriculture [3].
They occur in plants from the Violaceae (violet), Rubiaceae (coffee) and Cucurbitaceae (cucurbit) families and have a diverse range of
biological activities, including uterotonic, anti-HIV, antimicrobial, and insecticidal activities, the latter suggesting that their natural function is
in plant defence. Individual plants express suites of 10-100 cyclotides at high levels (2g/kg plant weight). Cyclotides typically comprise 30
amino acids, contain a head-to-tail cyclised backbone and incorporate three disulfide bonds arranged in a cystine knot topology. In this
motif an embedded ring in the structure formed by two disulfide bonds and their connecting backbone segments is penetrated by a third
disulfide bond. The combination of this knotted and strongly braced structure with a circular backbone renders the cyclotides impervious to
enzymatic breakdown and makes them exceptionally stable. The cyclotides are the largest of several groups of naturally occurring circular
proteins that have been discovered over recent years [4]. This presentation will describe the discovery of the cyclotides in plants, their
structural characterization, evolutionary relationships and their applications in drug design. Their stability and compact structure makes
them an attractive protein framework onto which bioactive peptide epitopes can be grafted to stabilize them. [1] Craik D J, Cemazar M,
Wang C, Daly N L: Biopolymers: Peptide Science 2006, 84, 250 [2] Craik D J, Cemazar M, Daly N L: Curr. Opin. Drug Discovery and
Development 2006, 9, 251 [3] Jennings C, West J, Waine C, Craik D, Anderson M. PNAS 2001, 98, 579 [4] Craik D J: Science, 2006, 311,
1561
(a) University of Queensland
M0902 Specialist herbivore evasion of plant defense elicitation: Engineered cATPC as a strategy to recover cowpea (Vigna
unguiculata) recognition and defense against velvetbean caterpillars (Anticarsia gemmatalis).
Schmelz, Eric A-presenter [email protected](a)
Alborn, Hans T (a)
Teal, Peter E.A. (a)
http://www.ars.usda.gov/pandp/people/people.htm?personid=11781
Plants are attacked by an array of generalist and specialist herbivores with respectively broad and narrow host ranges. Moreover, plants can
produce quantitatively different defense responses to attack by even closely related insects. This raises the following question: Are adapted
specialists better at avoiding the induction of plant defense responses than generalists? In cowpea ( Vigna unguiculata), attack by generalist
armyworms (Spodoptera spp.) elicits rapid plant defense responses due to inceptin [Vu-In; +ICDINGVCVDA-], a peptide derived from
chloroplastic ATP synthase Υ-subunit (cATPC) proteins present in their oral secretions (OS). In contrast to armyworms, OS from the legume
specializing velvetbean caterpillar (VBC; Anticarsia gemmatalis) do not trigger rapid bursts ethylene, jasmonic acid and salicylic acid in
wounded cowpea leaves. We examined the fate of cATPC proteins in VBC OS and discovered the preferential accumulation of a C-terminal
Ala truncated peptide [Vu-In-A; +ICDINGVCVD-]. Not only is Vu-In-A inactive as an elicitor, but also a naturally occurring competitive inhibitor
of inceptin-induced responses. Libraries for amino acid substitutions at the inceptin C-terminus were screened for differences in VBC gut
61
proteolysis. Two modified inceptin amino acid sequences were discovered that retained elicitor activity and displayed preferential
accumulation in VBC OS. VBC that previously ingested these modified cATPC polypeptide sequences elicited stronger plant responses in
natural feeding assays compared to appropriate control insects. We propose transgenic expression of heterologous proteins containing
modified cATPC sequences in legumes as a strategy to recover plant recognition and rapidly induced-defenses against a specialist herbivore.
(a) USDA-ARS Center for Medical, Agricultural and Veterinary Entomology
M0903 PROPEP Family Regulation of Pathogen Defense in Arabidopsis thaliana
Huffaker, Alisa-presenter [email protected](a)
Ryan, Clarence A. (a)
AtPep1 is a 23 amino acid peptide derived from the carboxyl terminus of a precursor protein encoded by the PROPEP1 gene of Arabidopsis
thaliana. Expression of the PROPEP1 gene is induced by methyl jasmonate and wounding, and the AtPep1 peptide specifically interacts with
an LRR-RK, PEPR1, to regulate expression of genes encoding the pathogen-defense proteins PDF1.2 (plant defensin) and PR-1
(pathogenesis response protein 1). Transgenic plants constitutively expressing the PROPEP1 gene also express PDF1.2 and PR-1 at levels
higher than in wild type plants and are more resistant to the root pathogen Pythium irregulare. Arabidopsis encodes five other PROPEP
genes, raising the question of whether these genes act redundantly, synergistically or differ functionally. Expression studies of the individual
PROPEP gene family members reveal differential induction in response to pathogens, elicitors and the defense-related hormones methyl
salicylate, methyl jasmonate and ethylene. The AtPep peptides encoded by these PROPEP genes differentially regulate expression of PDF1.2
and PR-1. To better understand the regulatory role of individual PROPEP genes, we are employing microarray analysis of global gene
expression patterns in transgenic plants overexpressing the different PROPEP genes. Additionally, we are investigating the role of individual
PROPEP genes in salicylate-associated defense responses by studying resistance of PROPEP-overexpression plants to infection with
Pseudomonas syringae pv. tomato DC3000. Based on our studies we hypothesize that peptides encoded by the PROPEP gene family
enhance pathogen defense responses by acting as endogenous signals to amplify defense signaling initiated by pathogens through both the
jasmonate/ethylene and salicylate pathways.
(a) Washington State University
M0904 Proteolytic processing of a plant peptide hormone by a subtilase in Arabidopsis
Srivastava, Renu -presenter [email protected](a)
Liu, JianXiang (a)
Howell, Stephen (a)
Phytosulfokines (PSKs) are secretory peptides with sulfated tyrosine residues known to promote cell proliferation in tissue cultures
(Matsubayashi and Sakagami, 2006, Ann. Rev. Plant Biol. 57, 649-674.) AtPSK4 from Arabidopsis is a five-residue peptide derived from a 79
residue prepropeptide precursor. We demonstrated that AtPSK4 is processed from its precursor by AtSBT1.1 (At1g01900), one of the 56
subtilisin-like serine proteases (subtilases) encoded in Arabidopsis genome. Processing was demonstrated by cleavage of a proAtPSK4-myc
transgene product to AtPSK4-myc in vivo. The precursor was not processed in sbt1.1-1 and sbt1.1-2, T-DNA knockout mutants in AtSBT1.1,
indicating that AtSBT1.1 is required for proAtPSK4 processing. Processing was also not observed in intact roots but was induced by
explanting roots and placing them into tissue culture. The gene encoding AtSBT1.1 was upregulated when roots were explanted suggesting
that activation of the proteolytic machinery which processes proAtPSK4 is dependent on AtSBT1.1 induction. A fluorogenic peptide
representing the putative subtilase recognition site in proPSK4 was cleaved in vitro by an affinity-purified AtSBT1.1. Alanine scans through
the recognition site peptide indicated that AtSBT1.1 is highly specific for the AtPSK4 precursor. MALDI-TOF analysis of the reaction products
revealed that the preferential site of cleavage was three residues upstream from the presumed N-terminus of the mature peptide indicating
that further processing at the N-terminus may be required for activation. Thus, a peptide growth factor that promotes callus formation in
culture is proteolytically processed by a specific plant subtilase encoded by a gene upregulated during the process of explanting tissue for
culture.
(a) Iowa State University
Date
SATURDAY
June 28
Start
5:10 PM
End
Minisymposium
6:50 PM Minisymposium 10 – Drought and Flooding Stress –
Chair: Alejandra Covarrubias
5:10 - M1001: Julia Bailey-Serres - Elucidation of the
Location
Siglo XXI Convention Center Salon Ekbalam
acclimation response of Arabidopsis seedlings to low oxygen
stress from the cellular to whole-plant level
5:35 - M1002: Alejandra Covarrubias - Translational regulation
conferred by the 3, untranslated region of a transcript encoding
a late embryogenesis abundant protein in response to water
deficit
6:00 - M1003: Gabriel Iturriaga - Improvement of drought
tolerance and grain yield in common bean by overexpressing
trehalose-6-phosphate synthase in rhizobia
6:25 - M1004: Yong-Fei Wang - SLAC1 is required for plant
guard cell S-type anion channel function in stomatal signalling
M1001 Elucidation of the acclimation response of Arabidopsis seedlings to low oxygen stress from the cellular to wholeplant level
Mustroph, Angelika (a)
Oosumi, Teruko (a)
Branco-Price, Cristina (a)
Hamersky, Kayla (a,b)
Jang, Charles (a,b)
Lee, Seung
Cho (a)
Ma, Kelvin (a)
Sorensen, Reed (a)
Larive, Cynthia (a)
Bailey-Serres, Julia-presenter [email protected](a)
Arabidopsis thaliana was used to elucidate mechanisms of acclimation to low oxygen (hypoxia) stress. To evaluate the intricate response,
we established transgenic lines that express a FLAG epitope-tagged ribosomal protein (RPL18) under the control of the CaMV 35S and celltype specific promoters. These lines were used to purify polysomal mRNAs from crude cell extracts of cryo-preserved samples by
immunoprecipitation. Microarray profiling of cell-specific polysomal mRNA populations was achieved for the root apex, whole root and aerial
organs of seedlings. All organs and cell types examined induced a general response to short-term hypoxia, which included increased
62
PB 2008
translation of a core of ~100 mRNAs. Specific responses of organs and cell-types were also resolved. The 35S:FLAG-RPL18 line was used to
study the dynamic response to hypoxia (2h or 9h), as well as re-oxygenation (9h hypoxia + 1h air). Profiling of immunopurified polysomal
mRNA and 1H-NMR quantitation of metabolites uncovered a rapid and reversible reconfiguration of carbon and nitrogen metabolism that
augments anaerobic ATP production. A major energy conserving mechanism was the dramatic inhibition of translation of over 60% of the
cellular mRNAs, which was almost completely reversed within minutes of reoxygenation. Although many strongly induced transcripts were
translated during the stress, some were recruited to polysomes only upon reoxygenation. Exploration of the biological function of 50 low
oxygen-induced proteins of unknown function using T-DNA insertion and/or overexpression mutants has led to the identification of
previously uncharacterized proteins that are critical to survival of Arabidopsis of low-oxygen and/or submergence stress. (Funding: NSF
2010 IBN-0420152 and IGERT DGE 0504249).
(a) Center for Plant Cell Biology, UC Riverside (b) ChemGen IGERT Program
M1002 Translational regulation conferred by the 3, untranslated region of a transcript encoding a late embryogenesis
abundant protein in response to water deficit
Covarrubias, Alejandra A.-presenter [email protected](a)
Battaglia, Marina (a)
In response to water deficit, higher plants induce a high accumulation of several transcripts including those encoding the late
embryogenesis abundant (LEA) proteins. To assure an efficient protein production under this stress condition, some of these transcripts
seem to be modulated at the translational level. Because in plants, little is known about the mechanisms involved in the selective translation
that usually occurs in response to different environmental stimuli, in this work we analyse the role of the 3, untranslated region (UTR) of the
water deficit responsive gene PvLEA18 from Phaseolus vulgaris on the regulation of its expression. Using constructs containing the GUS
reporter gene with and without the PvLEA18 3,UTR, driven by the PvLEA18 promoter, and introduced into Arabidopsis plants, we
demonstrate that the PvLEA18 3,UTR allows a preferential polysome loading of the GUS reporter transcript under water deficit. We also
show that a protein(s) is able to specifically interact with this 3,UTR, and we identify particular sequences that play an important role in this
interaction. Our data strongly support a major role of this 3,UTR and some mRNA binding proteins in the selective translational
enhancement of the PvLEA18 mRNA, which lead to an efficient protein synthesis and hence a competent response to this stress condition.
(a) Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico
M1003 Improvement of drought tolerance and grain yield in common bean by overexpressing trehalose-6-phosphate
synthase in rhizobia
Iturriaga, Gabriel-presenter [email protected](a)
Suarez, Ramon (a)
Wong, Arnoldo (a)
Ramirez , Mario (b)
Barraza, Aaron
(a)
Orozco, Maria del Carmen (a)
Cevallos, Miguel A (b)
Lara, Miguel (b)
Hernandez, Georgina (b)
Environmental conditions are severe limiting factors for growth and yield in crops. Osmotic adjustment and accumulation of compatible
solutes is a common response present in many microorganisms and plants. Trehalose, one of the most effective osmoprotectants, is a nonreducing disaccharide that occurs in many organisms including the symbiotic bacteria Rhizobium. Here we show the effects of
overexpressing trehalose-6-phosphate synthase in free-living Rhizobium etli and in symbiosis with Phaseolus vulgaris (common beans)
plants. Black bean plants inoculated with R. etli overexpresing trehalose-6-phosphate synthase gene had more nodules with increased
nitrogenase activity and higher biomass compared to plants inoculated with wild type R. etli, whereas plants inoculated with a R. etli mutant
in trehalose-6-phosphate synthase gene had fewer number of nodules and less nitrogenase activity and biomass. Three-week-old plants
subjected to drought stress fully recovered whereas plants inoculated with wild type or mutant strain wilted and died. The yield of bean
plants inoculated with R. etli overexpressing trehalose-6-phosphate synthase gene, and grown upon constant irrigation increased more than
50%. Macroarray analysis of 7200 ESTs from nodules of plants inoculated with the strain overexpressing trehalose-6-phosphate synthase
gene revealed up-regulation of genes involved in stress tolerance, carbon and nitrogen metabolism, suggesting a signaling mechanism for
trehalose. Thus, trehalose metabolism in rhizobia is key for signaling plant growth, yield and adaptation to abiotic stress.
(a) Centro de Investigacion en Biotecnologia-UAEM (b) Centro de Ciencias Genomicas-UNAM
M1004 SLAC1 is required for plant guard cell S-type anion channel function in stomatal signalling
Wang, Yong-Fei-presenter [email protected](a,b)
Triin , Vahisalu (a,c)
Julian , Schroeder (b)
Jaakko , Kangasjarvi
(c)
Hannes , Kollist (a,c)
Noriyuki , Nishimura (b)
Wai-Yin , Chan (b)
Gabriel , Valerio (b)
Airi , Lamminmaki (c)
Mikael ,
Brosche (c)
Heino , Moldau (d)
Radhika , Desikan (e,f)
Stomatal pores, formed by two surrounding guard cells in the epidermis of plant leaves, allow gas exchange in leaves and control
transpirational water loss to the atmosphere. Stomata restrict the entry of ozone - the major air pollutant with increasingly negative impact
on crop yields. The aperture of stomatal pores is regulated by transport of osmotically active ions and metabolites across guard cell
membranes. Despite the vital role of guard cells in controlling plant water loss and ozone sensitivity, genes encoding some of the major
regulators of stomatal movements remain unknown. Guard cell anion channels have been proposed to function as important regulators of
stomatal closure and to be essential in mediating stomatal responses to physiological and stress stimuli. However, genes encoding
membrane proteins mediating guard cell anion efflux have not been identified to date. Here we report the mapping and characterization of
an ozone sensitive Arabidopsis mutant, slac1. We show that SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1) is preferentially expressed in
guard cells and encodes a distant homolog of fungal and bacterial dicarboxylate/malic acid transport proteins with 10 predicted
transmembrane domains. SLAC1 is essential for stomatal closure in response to ABA, ozone, light/dark transitions, humidity change, Ca2+,
H2O2, and NO. Mutations in SLAC1 abolish cytosolic Ca2+- and ABA-activated slow (S-type) anion channel currents, but do not affect rapid
(R-type) anion channel or ABA-activated Ca2+ channels. A low homology of SLAC1 to bacterial and fungal malate transporters and the
disruption of S-type malate-permeable anion channels in slac1 mutants suggest a vital role for the plasma membrane protein SLAC1 in the
function of S-type anion channels.
(a) Co-first authors (b) Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla,
CA 92093-0116, USA. (c) Plant Biology, Department of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki,
Finland. (d) Institute of Technology, University of Tartu, Tartu 50411, Estonia. (e) Centre for Research in Plant Science, University of the
West of England, Bristol, UK. (f) Current address: Division of Biology, Imperial College London SW7 2AZ, UK.
63
MINISYMPOSIA – MONDAY JUNE 30
Date
MONDAY
June 30
Start
End
3:00 PM
Minisymposium
Location
4:40 PM Minisymposium 11 – Jasmonate Signaling – Chair: Gregg Siglo XXI Convention Center Howe
Salon Merida
3:00 - M1101: Edward Farmer - Jasmonate signalling and
attack-stimulated growth reprogramming
3:25 - M1102: John Browse - JAZ Repressor Proteins Control
Jasmonate Signaling
3:50 - M1103: Javier Narvaez-Vasquez - Systemic wound
signaling in tomato leaves is cooperatively regulated by
multiple plant peptides
4:15 - M1104: Carlos L. Ballare - Modulation of jasmonate
sensitivity by reflection signals. A phytochrome answer to the
dilemma of plants
M1101 Jasmonate signalling and attack-stimulated growth reprogramming
Farmer, Edward E.-presenter [email protected](a)
Transcriptional reprogramming within 3h of wounding affects the expression of an estimated 1.3% of protein coding genes in Arabidopsis.
The jasmonate signal pathway exterts control over the majority (67-84%) of these genes and expression patterns are globally similar in
wounded and unwounded leaves. Signal transfer from wounded to unwounded leaves takes place rapidly. Effects on the readily accessible
part of the proteome are more subtle but generally accord with transcript profiles. Rapid transcriptional responses provide less information
on interesting longer-term responses to wounding and herbivory. Wounding causes remarkable effects on leaf and petiole growth and on
whole plant architecture. These developmental responses to wounding require a fully functional jasmonate pathway. How is the growth
response to wounding controlled by the jasmonate pathway and how do attack-stimulated growth responses benefit the plant? We found a
natural transcript encoded by the gene JASMONATE ASSOCIATED1 (JAS1, also known as JAZ10) that, when overexpressed, can overcome
the effects of wound-repressed growth. Work on this gene identified the 19 amino acid core ‗Jas‘ motif as being important in woundstimulated growth control. By studying the molecular mechanism of jasmonate signaling alongside experiments on post-wound development
a more complete picture of what plants do promote their survival after attack is emerging. Field observations combined with laboratory
experiments are now providing new information on how jasmonate-controlled changes in plant architecture might help plants survive attack
by both specialised herbivores and by opportunistic organisms that have never evolved to be herbivores.
(a) University of Lausanne
M1102 JAZ Repressor Proteins Control Jasmonate Signaling
Browse, John-presenter [email protected](a)
Thines, Bryan (a)
Niu, Yajie (a)
Figueroa, Pablo (a)
Jasmonates (JA) are required for plant defense against insects and other arthropods, and also against many pathogens. In Arabidopsis JA is
also required for fertility. Despite the importance of JA signaling, many details of the signaling mechanism remain unknown. JA-synthesis
mutants, such as fad3,7,8 and opr3, are sterile and made fertile by application of JA. Mutations in the F-box protein COI1 also abolish JA
responses, but the coi1 phenotypes are not rescued by JA. Transcriptional profiling of opr3 stamens treated with JA, allowed us to identify
genes encoding 12 JAsmonate Zim-domain (JAZ) proteins that are key regulators of JA signaling. JAZ proteins act to repress transcription of
JA-responsive genes. JA treatment causes JAZ degradation by the SCF(COI1)/26S proteasome pathway. Furthermore, the JA-isoleucine
conjugate, but not other JA derivatives (such as JA, OPDA, or ME-JA), promotes interaction between COI1 and JAZ proteins in the absence
of other plant proteins. Our results suggest a model in which JA ligands promote the binding of the SCF(COI1) ubiquitin ligase to and
subsequent degradation of the JAZ repressor proteins, and implicate the SCF(COI1)-JAZ protein complex as a receptor for the plant
hormone JA-Ile. Many questions remain about the details of JAZ action and the roles played by conserved domains found in the family of
JAZ proteins. In particular two different models have been proposed to explain JAZ function (Nature 448:pp.661 & 666, 2007). We will
discuss these models in the context of new results obtained from protein-protein interaction studies and experiments with transgenic plants.
Our characterization of the JAZ family provides the basis for understanding the many different roles for JA in the development and
environmental responses of plants.
(a) Washington State University
M1103 Systemic wound signaling in tomato leaves is cooperatively regulated by multiple plant peptides
Narvaez-Vasquez, Javier-presenter [email protected](a)
Orozco-Cardenas, Martha L (a)
Ryan, Clarence A (b,b)
Hydroxyproline-rich glycopeptides containing 18-22 amino acids (HypSys peptides) were isolated recently from leaves of tobacco (Nicotiana
tabacum) and tomato (Solanum Lycopersicum) that are powerful inducers of protease inhibitor genes known to be induced by the defense
signaling peptide, systemin. The HypSys peptides are processed from polyprotein precursors, two from a tobacco precursor and three from
a tomato precursor. The tomato HypSys peptide precursor SlproHypSys, like the systemin precursor, prosystemin, is synthesized in phloem
parenchyma cells, and both precursor genes are expressed in tomato leaves in response to wounding and methyl jasmonate. Here we
demonstrate that the systemic wound expression of defense genes in tomato plants depends upon the cooperative synthesis of both
prosystemin and SlproHypSys to produce strong systemic wound response in tomato plants. The peptide signals derived from the
precursors amplify the synthesis of jasmonate, and in turn the peptides themselves. This provides a feed back loop to increase levels of
jasmonate in the vascular bundles as it moves through the plant as a long distance signal. This report provides the first demonstration of
the involvement of multiple plant peptides in regulating plant defense signaling.
(a) University of California Riverside-Botany and Plant Sciences Department (b) Washington State University-Institute of Biological Chemistry
64
PB 2008
M1104 Modulation of jasmonate sensitivity by reflection signals. A phytochrome answer to the dilemma of plants
Ballare, Carlos L.-presenter [email protected](a)
Moreno, Javier E (a)
One of the most widespread responses of plants to the attack of herbivore insects is the activation of chemical defenses. Previous studies
have shown that plants down-regulate the expression of chemical defenses when they perceive an increased risk of competition with
neighboring plants. In the experiments reported here we provide evidence that this down-regulation of defense is mediated, at least in part,
by an effect of phytochrome on the sensitivity of the plant to jasmonic acid (JA). Plants exposed to supplementary far-red radiation (FR), a
competition signal perceived by phytochrome, had reduced levels of defenses compared to control plants grown without FR
supplementation. This was demonstrated by measurements of phenolic compounds and direct evaluations of plant tissue quality using
bioassays with Spodoptera frugiperdalarvae. Several JA-inducible genes were up-regulated in response to feeding by S. frugiperda
caterpillars in control plants, but this up-regulation was absent in plants exposed to FR radiation. Exogenous application of MeJA caused an
increase in the levels of phenolic compounds and up-regulated genes putatively involved in JA signaling and response. When the plants
were exposed to reflected FR, the phenolic response was abolished and the up-regulation of gene expression was cancelled or greatly
reduced in the case of ERF1, a regulator of JA- and ethylene-inducible genes, and PDF1.2 and HEL, two markers of JA response. The JAinduced expression of MYC2 and VSP1, in contrast, was not affected by FR. We conclude that selective de-sensitization to jasmonates is the
mechanism whereby the plant switches it resource allocation strategy, from defense to shade avoidance, in response to phytochromeperceived signals of intense future competition.
(a) IFEVA, Universidad de Buenos Aires
Date
MONDAY
June 30
Start
3:00 PM
End
Minisymposium
4:40 PM Minisymposium 12 - Small Regulatory RNAs and
Chromatin Remodeling – Chair: Jose L. Reyes
3:00 - M1201: Federico Sanchez - MicroRNA167 familiy: new
Location
Siglo XXI Convention Center Salon Valladolid
insights on the auxin metabolism regulation in Phaseolus
vulgaris roots
3:25 - M1202: Jose L. Reyes - Conserved and Novel microRNAs
in the legume Phaseolus vulgaris in response to ABA and
drought
3:50 - M1203: Michael Axtel - Whole-transcriptome
identification of Arabidopsis microRNA targets
4:15 - M1204: Justin W. Walley - Stress induced chromatin
remodeling differentially regulates plant stress signaling
pathways
M1201 MicroRNA167 familiy: new insights on the auxin metabolism regulation in Phaseolus vulgaris roots .
Sanchez, Federico-presenter [email protected](a)
Estrada-Navarrete, Georgina (a)
Pelaez, Pablo (a)
Reyes, Jose L
(a)
Arenas , Catalina (a)
Covarrubias, Alejandra (a)
Quinto, Carmen (a)
Cardenas, Luis (a)
Alvarado-Affantranger, Xochitl
(a)
MicroRNAs (miRNAs) are 20-22 nucleotides long, non-coding RNAs that regulate mRNAs levels and play important roles in development,
stress and defense responses. MiRNAs are well known to inhibit the translation of mRNAs into protein and promote mRNA degradation
(Fillipowicz et al., 2008). The signaling pathway of the phytohormone auxin is significately regulated by miRNAs. At least 7 of the 23 ARFs
(auxin response factors) in Arabidopsis are directly or indirectly regulated by MicroRNAs. Auxin signaling is required for plant defense,
growth and development. A plant miRNA (miR393) contributes to antibacterial resistance by repressing auxin signaling (Navarro et al.,
2006). The members of the microRNA167 family have as targets the transcription factors ARF6 and ARF8. MiR160 regulates ARF10, ARF16
and ARF17 (Rhoades et al., 2006). In Arabidopsis miRNA167 regulates female and male reproductive organs (Wu, et al., 2006). Here, we
describe two common bean miRNAs corresponding to miR160 and miR167 families. Both miRNAs were induced in common bean roots by
auxin and after Rhizobium tropici inoculation. ESTs encoding transcriptional factors involved in auxin signaling in P. vulgaris were identified
to be targeted by members of the miR167 family. We will present the expression analysis of three precursors of the miR167 family and the
phenotypes of common bean transgenic roots over-expressing the bean miR167 precursors found. (Estrada et al., 2007). This work was
partially supported by grants IN208407 and CONACYT 42562-Q.
(a) Instituto de Biotecnologia
M1202 Conserved and Novel microRNAs in the legume Phaseolus vulgaris in response to ABA and drought
Reyes, Jose L-presenter [email protected](a)
Arenas, Catalina (a)
Perez, Beatriz (a)
Rabanal, Fernando (a)
Estrada, Georgina
(a)
Sanchez, Federico (a)
Covarrubias, Alejandra (a)
In plants, drought stress produces several physiological and cellular changes, with abscisic acid (ABA) signaling playing a central role in
mediating the corresponding responses. Phaseolus vulgaris (common bean) represents an important crop in Mexico, and it provides a
unique model for the analysis of different adaptation strategies. We are exploring the participation of microRNAs in the regulation of
processes related to perception/adaptation to drought stress and other external stimuli. To address this question, we have constructed
cDNA libraries to identify small RNAs present under optimal conditions, water stress conditions or after ABA treatment. To date, we have
found microRNAs conserved in Arabidopsis and other species as well as sequences representing potential microRNAs. We will present the
characterization of novel microRNAs we have found as specific to the legume lineage and their relationship to stress responses. In addition,
we will show the development of experimental tools to study microRNAs in this and other model legumes such as Medicago truncatula or
Lotus japonicus.
(a) Instituto de Biotecnologia-UNAM
M1203 Whole-transcriptome identification of Arabidopsis microRNA targets
Addo-Quaye, Charles (a,c)
Eshoo, Tifani W (a,d)
Bartel, David P (e,f)
Axtell, Michael J-presenter [email protected](a,b)
65
MicroRNAs (miRNAs) regulate the expression of target mRNAs in plants and animals. Plant miRNA targets have been predicted based on
their extensive and often conserved complementarity to the miRNAs, as well as from miRNA over-expression experiments; many of these
target predictions have been confirmed by isolating the products of miRNA-directed cleavage. Here, we present a transcriptome-wide
experimental method to directly detect cleaved miRNA targets without relying on predictions or over-expression. The 5‘ ends of polyadenylated, uncapped mRNAs from Arabidopsis were directly sampled resulting in an empirical snapshot of the ―degradome‖. miRNAmediated cleavage products were easily discerned from an extensive background of degraded mRNAs, which collectively covered the
majority of the annotated transcriptome. Many previously known Arabidopsis miRNA targets were confirmed and several novel targets were
also discovered. Quantification of cleavage fragments revealed that those derived from TAS transcripts, which are unusual in their
production of abundant secondary siRNAs, accumulated to very high levels. This accumulation suggests that high expression levels and/or
stabilization of TAS cleavage products might play a role in secondary siRNA biogenesis. This empirical method is broadly applicable to
discover and quantify cleaved miRNA targets without a priori predictions.
(a) Pennsylvania State University (b) Department of Biology (c) Department of Computer Science and Engineering (d) Cell and
Developmental Biology Program, Huck Institutes of the Life Sciences (e) Whitehead Institute (f) Howard Hughes Medical Institute and
Department of Biology, Massachusetts Institute of Technology
M1204 Stress induced chromatin remodeling differentially regulates plant stress signaling pathways
Walley, Justin W.-presenter [email protected](a)
Dehesh, Katayoon (a)
Organisms are continuously exposed to a myriad of environmental stresses. Central to an organism‘s survival is the ability to mount a robust
transcriptional response to the imposed stress. An emerging mechanism of transcriptional control involves dynamic changes in chromatin
structure. Two main mechanisms are involved in altering chromatin structure: chromatin modifications, which covalently modify histone
proteins; and chromatin remodeling, which utilizes ATP hydrolysis to alter histone-DNA contacts. Considerable evidence demonstrating that
chromatin modifications are critical for plant stress tolerance has been reported while chromatin remodeling has received little attention.
Here, we provide genetic, biochemical and biological evidence that chromatin remodeling is required for pathogen resistance. We identified
a chromatin remodeling protein required for the expression of specific defense genes and that is directly recruited to the promoter of
several of these genes. Furthermore, we show that this protein is required for resistance to specific pathogens. These findings demonstrate
not only that chromatin remodeling is required for selective pathogen resistance, but also that chromatin remodelers can regulate specific
pathways within stress signaling networks.
(a) University Of California, Davis
Date
MONDAY
June 30
Start
3:00 PM
End
Minisymposium
4:40 PM Minisymposium 13 – Environmental Sensing and
Responses – Chiar: Elaine Tobin
3:00 - M1301: Javier Lopez - Overexpression of Arabidopsis
Location
Siglo XXI Convention Center Salon Izamal
CRY1 affects tomato growth, chlorophyll, anthocyanin and
lycopene contents in fruit
3:25 - M1302: Frank Harmon - Temperature entrainment of the
Arabidopsis circadian clock requires ELF3 activity
3:50 - M1303: Shen X. Lu - Testing time: Can a pulse of
proposed oscillator components shift rhythms in Arabidopsis?
4:15 - M1304: Peter V. Minorsky - Infradian Rhythms in Bean
Seed Imbibition -- Not the Moon, the Sun!
M1301 Overexpression of Arabidopsis CRY1 affects tomato growth, chlorophyll, anthocyanin and lycopene contents in fruit
Lopez, Javier-presenter [email protected](a)
Wang, Xingjun (b)
Lee, Janet (c)
Yu, Xuhong (c)
Lin , Chentao (c)
Light is one of the most important environmental factors controlling plant development. Blue light is perceived in plants by photoreceptors
including phytochrome A, Nph1/phototropin and cryptochromes. Cryptochromes are blue/ultraviolet-A absorbing flavoproteins that share
structural similarity to DNA photolyase but lack photolyase activity. Cryptochromes are involved in the control of circadian timing,
deetiolation and photoperiodic flowering. Functional characterization of Arabidopsis cry1 mutants has shown that CRY1 is mainly involved in
the control of photomorphogenesis, including hypocotyl elongation and anthocyanin biosynthesis. Very little scientific information about
cryptochrome 1 function in plants other than Arabidopsis is available. To explore the function of Arabidopsis cryptochrome 1 in other plant
species, we generated the transgenic tomato lines overexpressing AtCRY1:GFP fusion under the control of 35S promoter. The AtCRY1:GFPoverexpressing tomato seedlings showed a hypersensitive photoresponse in the inhibition of hypocotyl elongation in response to blue light
but they had no difference compared to the wild type while grown under far-red, red and dark conditions. Chorophyll, anthocyanin and
lycopene contents in AtCRY1:GFP-overexpressing plants were significantly higher compared to the wild type plants. The AtCRY1:GFP fusion
protein expressed in transgenic tomato plants is shown to accumulate mainly in the nucleus. Our results suggest that the molecular
mechanism of cryptochrome 1 is conserved between Arabidopsis and tomato regarding the blue light inhibition of hypocotyl elongation.
However, Arabidopsis cryptochrome 1 can also be explored to be involved in the lycopene biosynthesis in tomato.
(a) Instituto Tecnologico del Valle de Oaxaca. 68000 Oaxaca, Mexico (b) High Technological Research Center, Shandong Academy of
Agricultural Sciences. Jinan 250100 China. (c) Molecular, Cell and Development Biology Department, University of California, Los Angeles,
90095 CA, USA.
M1302 Temperature entrainment of the Arabidopsis circadian clock requires ELF3 activity
Harmon, Frank-presenter [email protected](a,b)
Circadian clocks maintain approximately 24 hour rhythms in a variety of physiological processes. These internal rhythms are coupled with
environmental cycles through a process called entrainment. Changes in both light and temperature serve as cues for entrainment of the
66
PB 2008
clock in plants. In Arabidopsis thaliana, temperature cycles that differ by as little as 4οC (i.e. , 22οC to 18οC) are sufficient to entrain the
circadian oscillator. The mechanism by which temperature is perceived and transmitted to the clock is largely unknown. Previous work has
implicated EARLY FLOWERING 3 (ELF3) in light input to the oscillator, where ELF3 allows the clock to progress past a light sensitive phase
in the evening. In the absence of this activity, the clock rapidly arrests in constant light conditions. We find that ELF3 activity is also vital for
proper circadian rhythms following temperature entrainment in the complete absence of light. Etiolated elf3 seedlings grown in temperature
cycles lack detectable rhythms after release into constant temperature, whereas wild type seedlings exhibit robust rhythms after the same
treatment. Overall, the circadian phenotype of etiolated, temperature-entrained elf3 seedlings closely matches the light-grown phenotype.
Thus, ELF3 may have a common function for both temperature and light signals. This study suggests that ELF3 is a potential point of
convergence for light and temperature information.
(a) Plant Gene Expression Center USDA-ARS (b) Department of Plant & Microbial Biology, UC Berkeley
M1303 Testing time: Can a pulse of proposed oscillator components shift rhythms in Arabidopsis?
Lu, Sheen X-presenter [email protected](a)
Knowles, Stephen M (a)
Tobin, Elaine M (a)
Circadian rhythms are generated by endogenous central oscillators that respond to input from the environment and regulate rhythmic
outputs. In the model plant Arabidopsis, although many components that affect rhythms have been identified and have been used to
propose models of the circadian clock, none have been conclusively shown to be part of a central oscillator. Here we prove that the MYBrelated transcription factors CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) are components of the
central oscillator in Arabidopsis. We found that in addition to exhibiting properties that have suggested they serve such a role, a pulse of
expression of these factors results in dramatic phase-shifts in several different rhythms of gene expression. These include CAB::LUC, a
circadian reporter gene, and clock-associated genes such as TIMING OF CAB 1 (TOC1) and GIGANTEA (GI). In contrast, pulsing TOC1
expression, a previously proposed component of the Arabidopsis central oscillator, did not result in such shifts. Our results prove
conclusively that CCA1 and LHY are central oscillator components in plants and suggest that TOC1 cannot by itself serve such a function.
The use of the ethanol inducible system also provides a means for experimentally testing the effect of a pulse of virtually any protein.
(a) University of California, Los Angeles
M1304 Infradian Rhythms in Bean Seed Imbibition -- Not the Moon, the Sun!
Minorsky, Peter V.-presenter [email protected](a)
Thirty years ago, a debate raged concerning the nature of biological rhythms. The endogenous school argued that biological rhythms
occurring in the absence of corresponding oscillations in any known environmental parameter arise endogenously within the organism itself.
The exogenous school on the other hand proposed that biological rhythms reflect organismal responses to subtle and pervasive exogenous
factors such as geomagnetism or cosmic radiation. Much of the debate between the endogenous vs. exogenous schools focused on the
nature of circadian rhythms in particular. The demonstration that circadian rhythms continue in orbiting spacecraft was widely regarded as
the final nail in the coffin of the exogenous school, and the entire school sank into obscurity. Regrettably, the demise of the exogenous
school also caused some interesting results concerning non-circadian rhythms to fall into oblivion as well. The present contribution concerns
one such rhythm, namely the infradian rhythms that occur in the uptake of water by imbibing bean (Phaseolus vulgaris) seeds. Bean seeds
have previously been reported to display rhythms in seed swelling (% weight gain after 4 h of imbibition) that have circa-weekly or circafortnightly periodicities. The original discoverers of these rhythms speculated that they might be related to the phases of the 29-day lunar
cycle, even though the periods of these rhythms can be circa-weekly or circa-fortnightly, and their points of inflection do not necessarily
coincide with distinct points in the lunar cycle. Based on 13 months of daily measurements, I have uncovered a positive correlation (r =
0.61) between seed imbibition and Bz, a vector component of the interplanetary magnetic field (IMF) during periods of negative polarity
(toward the sun; Bx > 0), conditions under which the connectivity of the IMF to the Earth‘s magnetic field is maximum. Phase-shifting the
Bz data during periods of negative polarity back 27 or 28 days also revealed a strong correlation. The data suggest that the ultimate causes
of infradian rhythms in imbibing bean seeds are changes in the IMF magnetic sector structure associated with the 27.3-day solar rotation
cycle and sub-harmonics of that cycle. These results explain not only the enigmatic circa-weekly and circa-fortnightly rhythms in bean seed
imbibition but also underscore the importance of space weather as an underappreciated environmental determinant of plant function.
(a) Mercy College
Date
MONDAY
June 30
Start
3:00 PM
End
Minisymposium
Location
4:40 PM Minisymposium 14 - Tomato and Solanaceous Species Siglo XXI Convention Center – Chair: Ilan Paran
Salon Progreso
3:00 - M1401: Greg Maloney - Branched-Chain Amino Acid-
Derived Flavor Volatiles in Tomato Fruit
3:25 - M1402: Antonio J. Matas - Cell type specific gene
discovery in tomato fruit using laser capture microdissection
and pyrosequencing
3:50 - M1403: Hui Kang - Involvement of a MADS-box gene,
jointless, in multiple hormonal regulation of tomato
development
4:15 - M1404: Ilan Paran - Common and unique regulation of
sympodial shoot development in pepper and tomato
M1401 Branched-Chain Amino Acid-Derived Flavor Volatiles in Tomato Fruit
Maloney, Greg S-presenter [email protected](a)
Klee, Harry J (a)
Fresh tomato fruit flavor is a combination of the interactions between sugars, acids, soluble solids, and volatile compounds. There are ~20
volatiles which are important for tomato flavor and they include the breakdown products of fatty acids, carotenoids, and amino acids. The
branched chain amino acids are thought to be the precursors to the flavor volatiles 2- and 3-methylbutanol and 2- and 3-methylbutanal, all
of which are important tomato flavor compounds. The pathway from amino acids to volatile compounds has been elucidated in yeast, which
67
produces these same flavor volatiles in beer, bread, and cheese. Less is known about these pathways in fruit, though there is evidence that
the same pathway occurs in plants. The pathway has three major steps: (1) Deamination of the amino acid to an α-ketoacid by a
transaminase, (2) Decarboxylation of the α-ketoacid to an aldehyde by pyruvate decarboxylase, and (3) Reduction of the aldehyde to a fusel
alcohol via aldehyde dehydrogenase. We have shown the conversion of branched-chain amino acids to these volatiles in tomato fruit by
metabolite feeding coupled to GC-MS. We have identified 6 branched-chain aminotransferases (BCATs) in tomato. The two BCATs most
highly expressed in fruit have been successfully expressed in E. coli. In vitro assays indicate the enzymes use branched-chain amino acids
as substrates. These results reveal that tomato has a branched-chain amino acid catabolism pathway similar to that in yeast. Confirmation
of these in vitro results in planta is underway.
(a) University of Florida
M1402 Cell type specific gene discovery in tomato fruit using laser capture microdissection and pyrosequencing
Matas, Antonio J-presenter [email protected](a)
McQuinn, Ryan (b)
Fei, Zhangjun (b)
Giovannoni, James J (b,c)
Rose, Jocelyn
K.C. (a)
http://labs.plantbio.cornell.edu/rose/
Studies of gene expression in tomato fruit typically use homogenized entire pericarp material and there is generally an implicit assumption,
when describing and interpreting the data that result from such studies, that fruit flesh is uniform. However, the pericarp comprises a range
of cell types and many reports suggest a remarkably different genetic and biochemical landscape among different pericarp zones that is
associated with differential cell development, and both primary and secondary metabolism. Even attempts to address cell type specific
expression in fruit, targeting the skin, have used peels which results in the removal of the cuticle, the outer epidermal cell layer and varying
amounts of hypodermis. We are using a strategy that couples laser-captured microdissection with 454 sequencing to profile cell-type
specific gene expression in tomato fruit during ripening, and similarly in other Solanaceous species. This will generate robust gene
expression data for fruit pericarp tissues that will include new gene sequences currently not available in the tomato EST, microarray or
tomato genome sequencing projects. This integrated systems approach will better define the inventory and diversity of biochemical
pathways, patterns of gene expression and regulatory networks among fruit within the Solanaceae. Direct comparisons of gene expression
in these tissues, combined with comparison of metabolite data, will also allow the identification of quality related genes, including those
associated with carotenoids, flavonoids, general ripening, specific ripening traits likely differentiated between these tissues, and changes in
cuticle biosynthesis or cell wall architecture.
(a) Department of Plant Biology, Cornell University, Ithaca (b) U.S. Department of Agriculture / Agriculture Research Service, Plant, Soil, and
Nutrition Laboratory, Ithaca, NY (c) Boyce Thompson Institute for Plant Research
M1403 Involvement of a MADS-box gene, jointless, in multiple hormonal regulation of tomato development
Kang, Hui-presenter [email protected](a)
Jointless is a MADS-box gene that has been proven to play a key role in tomato flower pedicel abscission zone development. In jointless
plants, some inflorescence meristems also revert to vegetative growth, their flowering time is delayed, and the sympodial identity in
inflorescence meristems of jointless is suppressed. However, we still don‘t know how jointless causes the pleiotropic effects. Here we report
more evidence that jointless is a pleiotropic regulator of tomato development and it might affect the cross-talk between different plant
hormonal signals in tomato. Comparing to wild type plants, jointless has heavier seeds and fruits, delayed germination, thicker, longer
hypocotyls and hypocotyls cells, more root hairs and internodes. These phenotypes are similar to those of some plant hormonal mutants. To
determine whether jointless affects the perception or production of plant hormones, dose response experiments to six major plant
hormones and some of their inhibitors were performed. The results show that jointless seedlings are hypersensitive not only to external
hormones such as auxin, ethylene, gibberellin (GA), and brassinolides but also to the GA synthesis inhibitor paclobutrazol (PAC), auxin
transportation inhibitor N-1-Naphthylphthalamic Acid (NPA). Further experiments such as semi-quantitative RT-PCR and real-time PCR are
being performed to explore how different plant hormones affect the expression level of jointless in wild type seedlings and whether the
genes that are involved in plant hormonal signals have different expression levels in jointless. We propose that jointless might affect the
perception or production of multiple plant hormones and/or the cross-talk between them, leading to its pleiotropic effects on tomato
development.
(a) Plant Molecular Biology Center, Biological Sciences Department, Northern Illinois University
M1404 Common and unique regulation of sympodial shoot development in pepper and tomato
Cohen, Oded (a)
Borovsky, Yelena (a)
Eshed, Yuval (b)
Paran, Ilan-presenter [email protected](a)
Pepper and tomato are both closely related Solanaceae species with sympodial shoot development i.e., their shoot is terminated by a
flower. In pepper two sympodial shoots are developed after bifurcation of the primary stem, while tomato has a single shoot. In pepper,
each sympodial unit consists of two leaves and a single terminal flower while in tomato, each unit consists of three leaves and an
inflorescence. These differences account for the bushy pepper and the vine type tomato growth. We studied mutants impaired in
homologous genes affecting growth habit in both species. We found that fasciculate (fa), a pepper mutation characterized by determinate
growth is homologous to self pruning (sp) that causes precocious termination of sympodial shoots. While in fa the determinate growth is
associated with condensed sympodial units without changing their basic structure, in sp the determinate growth is associated with reduction
of leaf to flower ratio in the sympodial units. A new pepper mutant, late flowering (lfl), is disrupted in the pepper homolog of tomato
JOINTLESS where it is required for normal inflorescence development. Similarly to JOINTLESS, LFL acts to suppress vegetative growth in
the inflorescence meristem. However, while jointless exhibits normal sympodial growth, lfl sympodium has an increased leaf to flower ratio.
Furthermore, multiple flowers developed in lfl, indicate that the single flower in pepper is a reminiscence of an inflorescence and that LFL
along with other factors controls the early termination of the inflorescence meristem. In summary, the comparative analyses of homologous
mutations in the closely related pepper and tomato allow uncovering of mechanisms that control diversification in shoot architecture of the
two species.
(a) Agricultural Research Organization (b) The Weizmann Institute
68
PB 2008
Date
MONDAY
June 30
Start
End
5:10 PM
Minisymposium
6:50 PM Minisymposium 15 – Plant Herbivore Interactions –
Chair: Linda Walling
5:10 - M1501: Linda Walling - Leucine aminopeptidase: A key
Location
Siglo XXI Convention Center Salon Merida
regulator for insect defense
5:35 – Abstract 1502: Vijay Singh - Arabidopsis defense against
green peach aphid: role of plant lipids
6:00 – Abstract 1503: Holger Merker - Oldies but goldies: NAC
transcription factors and leucine aminopeptidase in plant
defense
6:25 – Abstract 1504: Gary W. Felton - Salivary Enzymes: The
First Line of Defense against Plant Defenses?
M1501 Leucine aminopeptidase: A key regulator for insect defense
Walling, Linda L.-presenter [email protected](a)
Fowler, John (a)
Narvaez-Vasquez, Javier (a)
Aromdee, Dale (a)
The tomato leucine aminopeptidase A (LAP-A) accumulates after herbivory. LapA genes are JA-responsive and regulated by the late branch
of wound signaling. To investigate the role of LAP-A in defense, transgenic tomato plants that down-regulate or ectopically express LAP-A
have been identified and characterized. Analysis of LapA-silenced (LapA-SI), -antisense (LapA-AS) and -over-expressing (LapA-OX) lines
showed that LAP-A regulates the late branch, but not the early branch, of wound signaling. LapA-OX tomato lines showed that LAP-A was
necessary but not sufficient for wound signaling in tomato. After wounding, Pin1, Pin2 and polyphenol oxidase (PPO) RNAs accumulated to
higher levels and persisted for longer times in LapA-OX than in wild type plants. Reciprocally, LapA-SI and LapA-AS plants accumulated less
Pin1, Pin2 and PPO RNA and less Pin protein after wounding. Exogenous methyl jasmonate (MeJA) treatments of LapA-SI and LapA-AS lines
revealed that MeJA could not restore wound signaling. Furthermore, JA perception appears to be intact as determined by root elongation
phenotypes in the presence of MeJA. Collectively, these data indicate that LapA regulates an event downstream of JA biosynthesis and
perception. LapA-SI were hypersusceptible to caterpillar feeding and Manduca sexta performed better on LapA-SI than wild-type plants.
Reciprocally, LapA-OX plants were more resistant to M. sexta feeding incurring less tissue damage and inhibiting both caterpillar growth and
development. Current experiments focus on revealing the plastidial process regulated by LAP-A.
(a) University Of California
M1502 Arabidopsis defense against green peach aphid: role of plant lipids
Singh, Vijay-presenter [email protected](a)
Louis, Joe (a)
Morton, Jessica (b)
Reese, John C (c)
Shah, Jyoti (a)
Myzus persicae (Sulzer) Green peach aphid (GPA) is a generalist feeder and a well known pest of over a hundred economically important
plant species. We have established a GPA-Arabidopsis thaliana model system to identify and characterize genes involved in plant defense
against aphids. Using this system, we had previously demonstrated that the GPA inducible Arabidopsis PAD4 gene has an important function
in plant defense against aphid (Pegadaraju et al., 2005, 2007). PAD4 contributes to antibiosis and antixenosis (feeding deterrent).
Furthermore, we had shown that a recessive mutation in the Arabidopsis SSI2 gene results in heightened resistance to GPA that results
from increased antibiosis activity. Microarray analyses revealed that the MPL1 (MYZUS PERSICAE-INDUCED LIPASE 1) gene is expressed at
elevated level in the ssi2 mutant and in GPA-infested wild type (WT) plants. The ssi2-conferred heightened resistance to GPA was
attenuated in the ssi2 mpl1 double mutant plant. No-choice tests revealed that in comparison to the wild type plant, GPA fecundity was
higher on two independent mpl1 mutant T-DNA insertion lines. In contrast, choice tests showed no significant difference in GPA number on
the mutant versus the WT, and electrical penetration graph monitoring of aphid feeding behavior indicated no differences in aphid feeding
on the WT versus the mpl1 mutant plants. We conclude that MPL1 is involved in antibiosis and unlike PAD4 does not contribute in any
measurable form to antixenosis. The GPA infestation-induced expression of PAD4 and MPL1 were found to be independent of each other.
MPL1 encodes a putative lipase and SSI2 is a stearoyl ACP-desaturase. Based on these results we propose that a lipid(s), or a product
thereof, is involved in plant defense against GPA
(a) University of North Texas, Department of Biology (b) Kansas State University, Division of Biology (c) Kansas State University, Division of
Entomology
M1503 Oldies but goldies: NAC transcription factors and leucine aminopeptidase in plant defense
Merker, Holger-presenter [email protected](a)
Hartl, Markus (a)
Schmidt, Dominik D (a)
Baldwin, Ian T (a)
http://www.ice.mpg.de/itb/home/home_en.htm
The research field of plant defense against herbivores has evolved quickly starting with ―Bud‖ Ryan‘s work on herbivore-induced plant
proteinase inhibitors (PIs) up to the potential receptor of jasmonic acid (JA), the major component in the signaling cascade. So far, we have
developed a thorough understanding of the formation of JA and the downstream direct (PIs, toxins) and indirect (volatile organic
compounds) defenses. However, much less is known about intermediate regulatory steps. Most likely transcription factors (TFs) are involved
in controlling genes and pathways as key regulatory elements, allowing a plant to fine-tune its responses. To gain deeper insight into these
regulatory networks, our group uses the wild plant Solanum nigrum (black nightshade) as an ecological model species that has not been
under artificial selection for particular traits. This makes the plant particularly interesting as an ecogenetic model system because its traits
can be studied in the context of its natural habitat and the selection pressures that have shaped the plant‘s genome. Recently, a reverse
genetics method based on RNA interference called virus-induced gene silencing (VIGS) has been established as an important tool in plant
sciences with which to investigate gene function, especially in ‗non-model organisms‘ where complete genome sequence information is not
available. S. nigrum‗s phylogenetic proximity to tomato and potato allows us to use genetic tools that have been established for these crops.
Based on a VIGS method previously reported for Solanum species that did not work in our genotype of S. nigrum, we established a VIGS
protocol that proved highly successful for S. nigrum. We demonstrate its efficiency by using it to dissect two key elements in the defense of
S. nigrum against leaf-chewing herbivores: (1) SnNAC, a herbivore-induced NAC TF of the ATAF subfamily, plays a crucial role in mediating
69
plant responses to herbivorous insects. (2) As seen in tomato, a leucine aminopeptidase (LAP) clone ranks among the highest up-regulated
genes in S. nigrum upon attack by larvae of the solanaceous specialist Manduca sexta. Although plant LAPs have been intensively studied,
their functions in defense are still not completely resolved. Feeding M. sexta larvae in a cut-leaf assay with LAP-silenced plants provides the
first experimental evidence that LAP influences herbivore performance and therefore has a defensive function against arthropod herbivores.
(a) Max Planck Institute for Chemical Ecology
M1504 Salivary Enzymes: The First Line of Defense against Plant Defenses?
Felton, Gary W-presenter [email protected](a)
Eichenseer, Herb (b)
Ervin, Gary N (c)
We have characterized a salivary glucose oxidase in the polyphagous caterpillar Helicoverpa zea and found that it plays a role in suppression
of wound-induced defensive responses in some host plants. Additionally this multifunctional enzyme not only helps protect the caterpillar
from diseases, but it possesses enzymatic activity against a wide range of plant defensive metabolites possessing a glucosidic linkages.
Included in these substrates are known plant defenses including glucosinolates, cyanogenic glucosides, phenolic glucosides, and alkaloids
possessing glucose adducts. Further experiments indicate that glucose oxidase activity against glucosinolates suppresses isothiocyanate
production indicating its potential role in detoxification. We have screened nearly 100 caterpillar species across a multitude of lepidopteran
families for glucose oxidase and found a significant relationship between high enzyme activity and breadth of host range. Species with the
largest host range generally possessed higher levels of glucose oxidase. These new findings suggest that salivary secretions may be the first
line of defense against constitutive and inducible plant defenses.
(a) Penn State University (b) Pioneer, Johnston Iowa (c) Mississippi State University
Date
MONDAY
June 30
Start
5:10 PM
End
Minisymposium
6:50 PM Minisymposium 16 – Genome Evolution and
Comparative Genomics –Chair: Doreen Ware
5:10 - M1601: Xiaofan Zhou - The relationship of gene
Location
Siglo XXI Convention Center Salon Valladolid
evolutionary pattern and function of eukaryotic gene family
5:35 - M1602: Apurva Narechania - Toward a better
understanding of cereal genome evolution through ensembl
compara
6:00 - M1603: Nelson Avonce - The evolutionary history of the
plant trehalose biosynthesis genes.
6:25 - M1604: Raul Alverez-Venegas - The Highly Similar
Arabidopsis Homologs of Trithorax ATX1 and ATX2 Encode
Divergent Bichemical Functions
M1601 The relationship of gene evolutionary pattern and function of eukaryotic gene family
Zhou, Xiaofan-presenter [email protected](a)
Surcel, Alexandra (a)
Sun, Yujin (b)
Quan, Li (b)
Ma, Hong (a,b)
Gene families are known to evolve by the birth-and-death process. New genes arise through genome-wide/segmental duplication, tandem
duplication and other mechanisms like transposition. After that, some genes were retained during evolution while others were lost.
However, different gene families have distinct patterns of evolution, and the different mechanisms of gene duplication have different
contributions to these patterns. To study the relationship between gene function, gene duplication mechanism and evolutionary pattern, we
performed phylogenetic analyses of several gene families in eukaryotes that have different types of function. The results showed that these
families have very different evolutionary histories. The SMC (Structural Maintenance of Chromosome) gene family, which has a very
fundamental function, can be divided into 6 subfamilies, which were generated in the early ancestor of eukaryotes. One member of each
subfamily has been maintained in most of the eukaryotes, except the meiotic isoforms of SMC1 in vertebrates. In Arabidopsis and poplar,
we also detected an extra SMC gene in some subfamilies likely from whole genome duplication. In contrast, the KFB (Kelch-repeat
containing F-box protein) gene family, which is involved in regulated proteolysis, experienced rapid evolution in plants; it has had many
gene birth and death events. Our results also revealed a major contribution of tandem duplication to the evolution of KFB genes in
Arabidopsis. Furthermore, some gene families with similar functions but different ranges of specificities also show different evolutionary
patterns. We propose that the differences in evolutionary patterns might be related to varying selection pressure due to distinct roles that
these gene families play.
(a) Graduate Program in Cell and Developmental Biology, the Huck Institutes of Life Sciences, the Pennsylvania State University, University
Par (b) Department of Biology and the Huck Institutes of Life Sciences, 416 Life Sciences Building, the Pennsylvania State University,
University P
M1602 Toward a better understanding of cereal genome evolution through ensembl compara
Narechania, Apurva-presenter [email protected](a)
Stein, Joshua (a)
Spooner, William (a)
Wei, Sharon (a)
Pasternak, Shiran
(a)
Ware, Doreen (a,b)
The evolution of cereal genomes has been shaped by their history polyploidization events, subsequent rearrangement and duplicate gene
loss. Many questions remain, including the extent of lineage-specific rearrangements, selective forces that dictated the retainment of
duplicate genes, and the extent of conserved non-coding regions. The availability of three nearly complete cereal genomes (maize, rice and
sorghum) provides an unprecedented opportunity to use comparative genomics to answer these and other questions in the evolution of
plant genomes. We describe the use of Ensembl Compara‘s gene tree, whole genome alignment and syntenic region identification pipelines,
applied as part of the Maize Genome Sequencing Project. The algorithms employed identify highly similar regions between two large
sequences while allowing for segments without similarity, thus highlighting gene movement or genomic rearrangement within syntenic
blocks. The tetraploid nature of maize and its history of whole genome duplications suggest that much of its genome should have at least
two blocks that align to the same region of rice. Preliminary analysis using a pilot 22 megabase maize assembly spanning maize
chromosome 4 exhibits synteny to a comparably sized region on rice chromosome 2. In agreement with marker-based syntenic studies, we
70
PB 2008
show that this rice chromosome has a duplicate homelogue on maize chromosome 5.
(a) Cold Spring Harbor Labs (b) United States Department of Agriculture
M1603 The evolutionary history of the plant trehalose biosynthesis genes.
Avonce, Nelson-presenter [email protected](a,b)
Wuyts, Jan (c)
Van Dijck, Patrick (a,b)
http://bio.kuleuven.be/mcb
The non-reducing disaccharide trehalose and its intermediate trehalose 6-phosphate (T6P) are emerging as two molecules with an
increasing unexpected importance in plant cell biology and beyond. Recently it has been shown that trehalose (α-D glucopyranosyl 1, 1-α-D
glucopyranoside) metabolism plays an important role in plant development, carbohydrate metabolism, glucose sensing and ABA metabolism
suggesting a hormone function for T6P. The most common trehalose biosynthetic pathway involves two enzymatic reactions carried out by
the enzymes trehalose 6-phosphate synthase and trehalose 6-phosphate phosphatase, present in both prokaryotic and eukaryotic
organisms. The unknown origin and presence of the eukaryotic TPS multigene families in plants makes it a big challenge to understand the
role of trehalose metabolism. Here we show the origin and evolutionary history of the plant trehalose biosynthesis pathways. We
characterized a novel TPS-TPP bifunctional protein (TPSP) from the bacteria Cytophaga hutchinsonii and the whole TPS family of the algae
Ostreococcus tauri, as well as the trehalose phosphate phosphatase of the bacteria Rhodopherax ferrireducens likely members of the plant
class I, II and III ancestor groups. Our results shows that ChTPSP is a bifunctional protein resulted from a fusion of bacterial TPS and TPP
genes before the eukaryotic divergence. In the Eukaryote lineage these fused proteins were duplicated almost immediately to generate the
plant class I and II proteins. Class III proteins were recruited by plants from a different ancestor. Gene duplication and recruitment of new
regulatory elements present in higher plants were initiated very early in plant evolution.
(a) Department of Molecular Microbiology, VIB. (b) Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, K.U. Leuven.
(c) Bioinformatics Training and Service Facility (BITS), VIB.
M1604 THE HIGHLY SIMILAR ARABIDOPSIS HOMOLOGS OF TRITHORAX ATX1 and ATX2 ENCODE DIVERGENT
BIOCHEMICAL FUNCTIONS
Alvarez-Venegas, Raul-presenter [email protected](a,b)
Saleh, Abdelaty (b,c)
Avramova, Zoya (b,b)
Yilmaz, Mehtap
(b,d)
Oahn-Le, O (b,b)
Hou, Guichuan (b,e)
Sadder, Monther (b,f)
Al-Abdallat, Ayed (b,f)
Xia, Yuannan (g,b)
Lu, Guoqinq
(h,b)
Ladunga, Istvan (i,i)
http://raul.alvarez0.googlepages.com/home ; http://www.ira.cinvestav.mx/?id=53
Gene duplication followed by specialization is a potent force in the evolution of biological diversity. Duplicated genes (paralogs) may have
acquired different fates including silencing or null mutations, partitioning of functions to complement the range of activity of the ancestral
gene, or gain of novel functions. While it is logical to expect that paralogs encoding divergent proteins have evolved novel functions, it is
impossible to predict the outcomes from duplicated genes with highly preserved coding sequences. A comparative study of two highly
conserved duplicated genes, ARABIDOPSIS HOMOLOG of TRITHORAX1, ATX1, and ARABIDOPSIS HOMOLOG of TRITHORAX2, ATX2,
revealed complex relationships between the two paralogs displaying features of partial redundancy and of neofunctionalization. Even when
co-regulating shared targets, ATX1 and ATX2 employ different mechanisms. Most remarkable is the divergence of their biochemical
activities: ATX1 tri-methylates K4 of histone H3, while ATX2 is involved in H3K4 di-methylation. ATX2 provides the first example of a
separate K4-di-methyltransferase from the K4-trimethyltransferase activity known so far.
(a) CINVESTAV Campus-Guanajuato, Irapuato Gto., Mexico (b) School of Biological Sciences, UNL Lincoln NE 68588-0118 (c) North Carolina
State University Raleigh, NC 27606 (d) Dept. Mol. Cell Biol., Boston University, Boston, MA 02215 (e) Microscopy Facility, Appalachian State
University, Boone, NC 28608 (f) Faculty of Agriculture, University of Jordan, Amman 11942, Jordan (g) Genomics Core Research Facility,
Center for Biotechnology UNL, Lincoln NE 68588-0665 (h) Department of Biology, University of Nebraska at Omaha, NE 68182-0040 (i) UNL
Center for Biotechnology and Department of Statistics, UNL, Lincoln, NE 68588-0665
Date
MONDAY
June 30
Start
5:10 PM
End
Minisymposium
6:50 PM Minisymposium 17 – Hormones – Chiar: Marta Laskowski
5:10 - M1701: Xiaofeng Wang - Molecular mechanisms of
receptor kinase activation, dimerization and phosphorylation in
brassinosteroid signal transduction
5:35 - M17092: Jeff Shen - The WRKY transcription factor
superfamily mediates plant responses to several hormones
6:00 - M1703: Georgiana Ponce - Interplay of ethylene and
gravitropic stimulation regulates the pattern of cell
differentiation in root cap cells of maize roots
6:25 - M1704: Marta Laskowski - Rhizotaxy is regulated by
polar auxin transport
Location
Siglo XXI Convention Center Salon Izamal
M1701 Molecular mechanisms of receptor kinase activation, dimerization and phosphorylation in brassinosteroid signal
transduction
Wang, Xiaofeng-presenter [email protected](a)
Kota, Uma (a)
Kai, He (b)
Blackburn, Kevin (a)
Li, Jia (b)
Goshe, Michael
B (a)
Huber, Steven C (c)
Clouse, Steven D (a)
Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID INSENSITIVE 1
(BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) for hormone perception and signal transduction. To examine early events in BR
signaling, we previously identified multiple in vivo phosphorylation sites for BRI1 and used co-immunoprecipitation of epitope-tagged
proteins to show that the association and phosphorylation of BRI1 and BAK1 was affected by endogenous and exogenous BR levels (Wang
et al., 2005, Plant Cell 17, 1685). Using immunoprecipitation of epitope-tagged BAK1 from Arabidopsis plants followed by liquid
chromatography-tandem mass spectrometry (LC/MS/MS), we have now identified at least five in vivo phosphorylation sites in the kinase
domain of BAK1. Examination of the in planta function of these sites by mutational analysis has revealed that at least two of these sites are
71
critical for BAK1 kinase function and optimal BR signaling. We examined the association and phosphorylation of BRI1 and BAK1 in various
genetic backgrounds, including bri1 and bak1 null mutants, to elucidate the detailed mechanisms of phosphorylation and dimerization in
response to BR. Our in vivo and in vitro data is consistent with a sequential transphosphorylation model that has some similarities, but also
distinct differences, to the well known mechanisms of animal TGF-beta and receptor tyrosine kinase signaling. These studies should
enhance our understanding of early events in BR signal transduction as well as establish general modes of action for the large family of
plant receptor-like kinases.
(a) North Carolina State University (b) University of Oklahoma (c) University of Illinois
M1702 The WRKY transcription factor superfamily mediates plant responses to several hormones
Shen, Jeff-presenter [email protected](a)
Zou, Xiaolu (a)
Neuman, Dawn (a)
Kim, Ho Soo (b)
Song, Eun Hyeon
(b)
Chung, Woo Sik (b)
WRKY transcription factor proteins contain one or two WRKY domains, a 60 amino acids fragment with WRKYGQK at its N-terminus and a
zinc-finger motif at the C-terminus. They play key roles in senescence, seed coat and trichome development, seed size, biosynthesis of
starch and sesquiterpenes, and plant responses to biotic and abiotic stresses. More than 70 members of the WRKY gene family have been
found in Arabidopsis and about one hundred in the rice genome. One class of the rice WRKY genes, such as OsWRKY51 and -71, suppress
gibberellin (GA) induction of the alpha-amylase gene promoter; yet they have little effect on abscisic acid (ABA) induction of the HVA22
promoter. Another class of OsWRKY genes, such as OsWRKY72 and -77, function as activators of ABA signaling. The third class, such as
OsWRKY24, negatively regulates both GA and ABA signaling in aleurone cells. Salicylic acid (SA), which induces the expression of about
50% of WRKY genes, suppresses GA-promoted seed germination and induction of alpha-amylase genes. Some WRKY proteins bind to DNA
to regulate gene expression while others exert their roles via interactions with WRKY, DOF and MYB transcription factors, and other
proteins. Physical interactions of WRKY proteins with calmodulin suggest that WRKY transcription factors could be the terminal receivers of
calcium-mediated cell signaling relays that control plant growth and development.
(a) University of Nevada, Las Vegas, NV89154, USA (b) Gyeongsang National University, Jinju 660-701, Korea
M1703 Interplay of ethylene and gravitropic stimulation regulates the pattern of cell differentiation in root cap cells of
maize roots
Ponce, Georgina-presenter [email protected](a)
Bahena, Albina (a)
Puente, Catalina (a)
Cassab, Gladys I (a)
The root cap (RC) is an excellent model for studying plant signaling and behavior since it senses and responds to diverse stimuli. We
previously demonstrated that ethylene regulates RC size and cell differentiation, since its addion or inhibition or its synthesis, affected RC
development of maize roots (Ponce et al., 2005, Plant, Cell & Env 28: 719). In the presente study, we localized the gene product of a
specific clone of unknown function ZmT101T and examined the combined effect of ethylene and gravitropic stimulation in RC development.
ZmT101T co-localized with AVP1, a tonoplast protein marker, in the columella cells of RC. We found that both gravitropic stimulation and
the absence of ethylene increased not only the expression of a specific RC protein of unknown function (ZmT101T), but also changed their
pattern of expression in the RC. Furthermore, maize roots treated with ethylene showed an increase in the number of columella cells, but
their gravitropic response was similar to those untreated. However, when roots were pretreated with an inhibitor of ethylene synthesis,
which decreased the number of columella and border cells, their gravitropic response was similar to those untreated. In these conditions,
the regular mRNA expression of GDP-mannose-4, 6 dehydratase (another RC gene involved in the synthesis of fucose) in the columella cells
remained the same. These data indicates that gravitropic stimulation and ethylene has a profound effect on gene expression and
differentiation in the RC. It also indicates that an increase or decrease of columella cells, with the concomitant increase of amyloplasts,
observed upon addition or inhibition of ethylene synthesis has little influence in the gravitropic response of roots. Overall, we proposed that
the interplay of ethylene and gravity signaling in the RC might contribute to the plasticity of this structure and to its major role in root
signaling and behavior.
(a) Departamento de Biologia Molecular de Plantas, Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico
M1704 Rhizotaxy is regulated by polar auxin transport
Laskowski, Marta-presenter [email protected](a)
Hofhuis, Hugo (b)
Grieneisen, Veronica (c)
Hogeweg, Paulien
(c)
Scheres, Ben (b)
While the mechanisms that control phyllotactic patterning are increasingly understood, rhizotactic patterning, or the arrangement of lateral
organs along roots, has remained mysterious. In Arabidopsis, the pattern of emerged lateral roots can be described in terms of the
longitudinal spacing along the main root and a left-right component reflecting the fact that lateral roots can form along either of the two
pericycle cell files that lie adjacent to the protoxylem poles. Here, we show that a curved position increases auxin response on the outside
of the curve and induces lateral root initiation. An inducible system for lateral root initiation that relies on gravitropic responses was
developed, permitting live confocal imaging of roots in the hours leading up to founder cell specification. Localized increases in auxin
response in lateral root founder cells precede the first asymmetric divisions by about 3 hours. The longitudinal pattern of vascular PIN
expression is dynamic, and correlates with the pattern of founder cell specification. Distribution of the auxin import carrier AUX1:YFP also
changes in the hours leading up to founder cell specficiation. We present a model for lateral root positioning and propose that PINdependent changes in polar auxin transport currently used to describe phyllotactic patterning can be extended to the root.
(a) Biology Department, Oberlin College, USA (b) Department. of BIology, Utrecht University, the Netherlands (c) Theoretical Biology and
Bioinformatics, Utrecht University, the Netherlands
72
PB 2008
Date
MONDAY
June 30
Start
5:10 PM
End
Minisymposium
6:50 PM Minisymposium 18 – Plant Symbiont Interactions –
Chair: Carmen Quinto
5:10 - M1801: Luis Cardenas - Fast and transient intracellular
Location
Siglo XXI Convention Center Salon Progreso
ROS changes in living root hair cells responding to specific NFs
5:35 - M1802: Julia Frugoli - Regulation of nodule number in
Medicago truncatula: sunn, lss, rdn and rae
6:00 - M1803: Quan Zhang - Positional cloning of STR, a gene
required for arbuscular mycorrhizal (AM) symbiosis in Medicago
truncatula
6:25 - M1804: Ranamalie Amarasinghe - Transporters
operating at the plant-fungal interface in tall fescue- endophyte
symbiotic association; Novel insights from a nutritional stand
point.
M1801 Fast and transient intracellular ROS changes in living root hair cells responding to specific NFs
Cardenas, Luis-presenter [email protected](a)
Martinez, Adan (a)
Nava, Noreide (a)
Santana, Olivia (a)
Martinez, Nancy
(a)
Barroso, Ma. Luisa (a)
Martinez, Liliana (a)
Sanchez, Federico (a)
Quinto, Carmen (a)
http://www.ibt.unam.mx
The symbiotic interaction between rhizobia and leguminous plants is host specific and induces the formation of nitrogen-fixing root nodules.
Legume roots exude flavonoids that induce the expression of the bacterial nodulation genes, which encode proteins involved in the
synthesis and secretion of signals called Nod factors (NFs). These NFs signal back to the plant root and trigger several responses such as:
ion changes (K+, Cl-, Ca2+, H+), cytoplasmic alkalinization, calcium oscillations, gene expression, etc., leading to bacterial invasion and
nodule formation. The role of reactive oxygen species (ROS) in root-nodule development and metabolism has been extensively studied.
However, there is limited evidence showing ROS changes at the subcellular level during the earliest stages of the interaction between
legumes and rhizobia. Herein, increasing and transient ROS levels were detected at the tip of actively growing root hair cells, within seconds
after addition of Nod factors. This transient response (which lasted up to 3 minutes) is Nod factor specific since chitin oligomers
(pentamers) failed to induce a similar response. When chitosan, a fungal elicitor was used instead, a sustained increasing signal was
observed. Since ROS levels are transiently elevated after NFs perception, we propose that this ROS response is specific of the symbiotic
interaction. Furthermore, we discuss the remarkable spatial and temporal coincidences between ROS and calcium transiently increased
levels observed in root hair cells immediately after NFs perception.
(a) Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico
M1802 Regulation of nodule number in Medicago truncatula: sunn, lss, rdn and rae
Schnabel, Elise (a)
Smith, Lucinda (b)
Mukherjee, Arijit (a)
Long, Sharon (b)
Frugoli, Julia-presenter [email protected](a)
The symbiotic association of rhizobia and legumes (nodulation) involves complex molecular signal transduction between the bacteria and
the host plant, allowing legumes to grow in nitrogen-limiting soils. In the presence of sufficient nitrogen, nodulation is suppressed by the
plant, and even in nitrogen-limiting soils, the number of nodules that form is regulated by the plant. Using the model legume Medicago
truncatula, we have identified several independent mutations that disrupt the ability of the plant to regulate nodule number. These
supernodulating mutants form 5-10 fold more nodules than the wild type plants. The published sunn mutation is a mutation in a LRRreceptor kinase that results in short roots and altered auxin flux in addition to supernodulation. We report genetic interactions of sunn with
the as yet uncloned lss locus, as well as the rae mutation, a lesion in the M. truncatula cytokinin receptor CRE1 gene. When homozygous,
mutations in rae suppress the supernodulation phenotype of sunn, but not the short root phenotype. In contrast, mutations in lss give a
supernodulation phenotype when present in a single copy IF the sunn mutation is also present in a single copy. Alone, lss and sunn behave
as recessive mutations and grafting experiments show they control nodule number through a shoot-derived signal. A fourth supernodulation
mutant, rdn, regulates nodulation through a root signal and does not display genetic interactions with sunn and lss. We have tested
nodulation and root length responses of the different mutants to auxin, ethylene, auxin transport inhibitors, and nitrate; by grafting
experiments; and by examination of gene expression. With these data, we have begun to order the action of the supernodulation genes.
We have also identified three putative new mutations that affect the same pathway, suggesting that the regulation of nodule number is
complex and involves multiple genes, plant hormones, and tissues. This work is supported by NSF award No. IOS-0641848.
(a) Clemson University (b) Stanford University
M1803 Positional cloning of STR, a gene required for arbuscular mycorrhizal (AM) symbiosis in Medicago truncatula
Zhang, Quan-presenter [email protected](a)
Blaylock, Laura A. (a)
Harrison, Maria J. (a)
A mycorrhizal symbiosis mutant, str (stunted arbuscule), was identified from a screen of an EMS mutagenized Medicago truncatula (A17
ecotype) population. Mycorrhizal fungi Glomus versiforme, Glomus intraradices and Gigaspora gigantea are all able to penetrate the roots of
str but arbuscules formed are stunted and development appears to be arrested. Unlike other M. truncatula symbiosis mutants identified to
date, str has a wildtype nodulation phenotype and is therefore an AM symbiosis-specific mutant. str lacks a AM symbiosis-associated growth
response and does not show AM symbiosis-associated increase in shoot phosphate content that is observed in wildtype plants. str was
crossed to M. truncatula A20 ecotype and analysis of 8712 F2 and F3 plants enabled us to map str to a 230kb region. One gene (STR) in
this region showed a lower transcript level in str relative to wildtype. In str, this gene contains a single nucleotide change which results in a
premature stop codon. The wildtype STR gene successfully complemented the str mutant phenotype and restored wildtype arbuscules, thus
concluding the positional cloning of STR. Details of the positional cloning of STR and its potential role in the AM symbiosis will be discussed.
(a) Boyce Thompson Institute for Plant Research
73
M1804 Transporters operating at the plant-fungal interface in tall fescue- endophyte symbiotic association; Novel insights
from a nutritional stand point.
Amarasinghe, Ranamalie-presenter [email protected](a)
Hesse, Uljana (b)
Li, Haiquan (a)
Zhao, Patrick (a)
Schardl,
Christopher (b)
Young, Carolyn (a)
Epichloe endophytes are mutualistic fungal symbionts of cool-season grasses (Poaceae), known to confer growth advantages to its host.
However, the molecular basis of the interaction between the endophyte and the grass host remain largely unknown. As a step towards
understanding Grass-Epichloe interactions, we have focused on identifying transporter genes specifically expressed in this symbiotic
association. The genome of Epichloe festucae, a model endophyte, has been sequenced and assembled with a near complete coverage.
Using a bioinformatics approach based on nearest neighbor method to compare against the Transporter Classification Database
(www.tcdb.org), we have identified the putative transporter complement in the Epichloe genome. The same approach was used to analyze
over 17000 transcript assemblies from tall fescue, to identify a set of putative plant transporters. The respective transporter classifications
for the predicted genes were also determined. We utilized a quantitative qRT-PCR approach to compare the expression levels of various
transporter gene families in both plant and fungus. Comparing the expression levels in shoots and roots of endophytic vs non-endophytic
plants, we identified potential symbiosis related plant genes in MFS, POT, and DMT gene families. Comparing In planta expression levels to
those in cultured mycelia, we also identified a number of fungal transporters in families POT, DMT, Amt, MFS, MIP and Trk to be
significantly upregulated in symbiosis. Concurrent expression levels of various transporter gene families provided insights into the nutritional
aspects of the interaction. Further characterization and functional analysis of these transporters will be a substantial contribution towards
understanding plant-fungal interactions.
(a) Samuel Roberts Noble Foundation (b) University of Kentucky
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PB 2008
MINISYMPOSIA – TUESDAY JULY 1
Date
TUESDAY
July 1
Start
8:30 AM
End
Minisymposium
Location
10:10 AM Minisymposium 19 – Emerging Technologies – Chair:
Siglo XXI Convention Center Amit Dhingra
Salon Merida
8:30 - M1901: Erich Kombrink - The yeast three-hybrid system:
A screening platform for the identification of targets of small
signaling molecules
8:55 - M1902: Zhiyang Zhai - RNAi-in protoplasts as a rapid,
high-throughput procedure for targeted gene-inactivation and
functional analyses of Arabidopsis genes
9:20 - M1903: Mathew E. Hudson - Genomics of systemspecific model plants using next-generation sequencing
9:45 - M1904: Amit Dhingra - Enabling Targeted Resequencing
of Arbitrarily Long Conserved DNA Sequences
M1901 The yeast three-hybrid system: A screening platform for the identification of targets of small signaling molecules
Schneider, Katja (a)
Wang, Zhe Ming (b)
Cottier, Stephanie (a)
Kaiser, Markus (b)
Kombrink, Erich-presenter [email protected](a)
Multicellular organisms, whether plant or animal, coordinate their growth and development and many responses to the environment by
using small signaling molecules for communication between cells or organs. The established plant hormones include auxin, cytokinin,
gibberellin, brassinosteroids, abscisic acid (ABA), and jasmonic acid (JA), which mediate numerous physiological and biochemical responses.
However, in comparison to animal systems, our knowledge about the molecular mechanisms of hormone perception and signaling in plants
is still fragmentary, despite the success of identifying receptors for most of these highly active compounds. We initiated a direct search for
the primary targets of JA and ABA by using a new experimental approach, the yeast three-hybrid technology, which allows direct functional
cloning of proteins that interact with synthetic hybrid ligands in vivo. We synthesized several such hybrid ligands by coupling different JA or
ABA derivatives via PEG spacers to methotrexate and demonstrated that some of these compounds retained biological activity. Using several
cDNA libraries synthesized from several organs, tissues, and plants that have received different kinds of stress, the whole expressed
genome (proteome) of Arabidopsis thaliana can now be scanned for JA and ABA targets, thereby providing a system-wide overview of JAand ABA-binding proteins. Significantly, the development of the yeast three-hybrid technology for application to plant systems will allow the
systematic search for targets of other organic small molecules that can be converted to biologically active hybrid ligands and hence this
technology will be beneficial for the whole plant science community. Supported by the Max-Planck-Society and Deutsche
Forschungsgemeinschaft.
(a) Max Planck Institute for Plant Breeding Research, Department of Plant-Microbe Interactions, Carl-von-Linne-Weg 10, 50829 Koeln,
Germany (b) Chemical Genomics Centre, Otto-Hahn-Str 15, 44227 Dortmund, Germany
M1902 RNAi-in protoplasts as a rapid, high-throughput procedure for targeted gene-inactivation and functional analyses of
Arabidopsis genes
Zhai, Zhiyang-presenter [email protected](a)
Vatamaniuk, Olena K. (a)
The genome sequence of Arabidopsis has been available for more than seven years, but only about 17% of genes have ascribed functions.
The impeding step in their functional analyses is the availability of suitable reverse genetic tools. Commonly used approaches, including
transposon/T-DNA insertional mutagenesis, and double-stranded (ds)RNA interference (RNAi), are limited by the time and space required to
generate, isolate and maintain multiple mutant plant lines, and are not practical for rapid screens. To circumvent these difficulties, we
developed a procedure consisting of isolating protoplasts from Arabidopsis, and RNAi-based gene inactivation in these protoplasts. This
method allows rapid and high-throughput analyses of genes function that are time, space, and cost-efficient. The success of RNAi in
protoplast is contingent on the yield and transformation efficiency. For RNAi, in vitro synthesized dsRNAs against AtPCS-1 (dsRNAAtPCS-1),
encoding a phytochelatin synthase that is required for heavy metal tolerance, was transfected into protoplasts from wild type Arabidopsis.
In our method, one gram of tissues from 14-day-old seedlings yields 5x106-107 protoplasts; the transformation efficiency is more than 90%.
We also performed RNAi against GFP, the green fluorescence protein from Aequorea victoria. In this case, protoplasts were co-transfected
with dsRNAGFP and the vector expressing GFP. As determined by RT-PCR and fluorescent microscopy, levels of AtPCS-1 and GFP transcripts
and GFP-mediated fluorescence decrease by at least 80% after 24 h after transformation; these RNAi effects lasted for 96h. Currently, we
are developing rapid screening strategies based on selectable conditional phenotypes resulting from gene-inactivation.
(a) Cornell University
M1903 Genomics of system-specific model plants using next-generation sequencing
Hudson, Matthew E-presenter [email protected](a)
Varala, Kranthi (a)
Swaminathan, Kankshita (a)
Bellendir, Stephanie (a)
Next generation sequencing can be used to produce low-cost genomic resources for ―system specific‖ model plants: ones which are
specifically suited to a particular scientific question. While complete genome sequencing using short reads alone is not yet feasible for
higher eukaryotes, current technology can provide an aid to whole-genome sequencing for smaller genomes, and a route to gene-space
sequencing, molecular and cytological marker development, and detailed characterization of larger genomes. New and adapted sequence
analysis methods are necessary to facilitate these genomics projects. Results will be presented on data analysis methods and biological
insights from next-generation sequencing, and other compatible approaches including whole-genome polymorphism arrays, in the genus
Glycine.
(a) University of Illinois
75
M1904 Enabling Targeted Resequencing of Arbitrarily Long Conserved DNA Sequences
Wu, Changjun (b)
Kalyanaraman, Ananth (b)
Dhingra, Amit-presenter [email protected](a)
http://molecularplants.wsu.edu/research/dhingra/index.htm
As genome sequences are unraveled resequencing of additional genotypes will ensue. PCR based strategies for targeted resequencing will
find increasing application in concert with the next generation sequencing technologies. One such strategy called ASAP (Amplification,
Sequencing and Annotation of Plastomes) was described recently (Dhingra and Folta, 2005). We have developed a computational
component to enhance the capacity and application of PCR-based targeted resequencing to arbitrarily long conserved DNA targets that
show significant sequence conservation with its already sequenced counterparts in evolutionarily close relatives. We propose a new
formulation of the PCR primer design problem for arbitrarily long conserved DNA targets, and present an optimal primer pair selection
algorithm that maximizes the expected yield (measured in target base ``coverage‘‘) under practical settings. We implemented our algorithm
into a software program with a robust set of parameters. As a proof of concept, we validated our approach over plastid genomes derived
from five closely related species from the Solanaceae family. This test case represents a difficult dataset as the plastomes are known to
have rearrangements thus disrupting conservation along long stretches. Results show that the set of primer pairs selected by our method
can provide over 50% coverage over the entire length of the plastomes and over ~70% average coverage over 43 conserved genes. This
software can be integrated with metagenomics projects and other projects that involve mining of genotypic diversity.
(a) Department of Horticulture and Landscape Architecture, Washington State University (b) School of Electrical Engineering and Computer
Science, Washington State University
Date
TUESDAY
July 1
Start
8:30 AM
End
Minisymposium
10:10 AM Minisymposium 20 – Gene Regulation – Chair: JC Jang
8:30 - M2001: Colleen Doherty - Identifying Cold Regulatory
Networks in Arabidopsis
Location
Siglo XXI Convention Center Salon Valladolid
8:55 – Abstract 2002: Kenzo Nakamura - Sugar-regulated gene
expression and the control of seed oil synthesis in Arabidopsis
9:20 – Abstract 2003: David Skibbe - Mutator transposition
alters the transcriptome and proteome of developing maize
anthers
9:45 – Abstract 2004: JC Jang - P-bodies and ARE-mediated
post-transcriptome in plants
M2001 Identifying Cold Regulatory Networks in Arabidopsis
Doherty, Colleen-presenter [email protected](a)
Gilmour, Sarah J (a)
Myers, Susan (a)
Thomashow, Michael F (a)
Environmental stresses such as cold and drought have a significant impact on crop production and yield across the globe. We are interested
in understanding the mechanisms by which plants can sense and respond to low temperatures in an attempt to improve freezing tolerance
in crop species. A major mechanism that allows plants to survive freezing temperatures is the process of cold acclimation. After exposure to
low, non-freezing temperatures plants that are able to cold acclimate make changes that allow them to survive freezing. In the model plant
Arabidopsis, large transcriptional changes occur during the process of cold acclimation. One group of transcription factors, CBFs 1, 2, & 3
(DREB 1B, 1C, 1A) has been shown to contribute to the enhanced freezing tolerance through regulation of their target genes. Constitutive
expression of the normally cold-induced CBF transcription factors causes an accumulation of CBF target genes. The induction of this CBF
regulon provides the plant with enhanced freezing tolerance without a period of cold-acclimation (1, 2). However, the CBF regulon
comprises less than 20% of cold-induced transcriptional changes and there is evidence for other cold-acclimation pathways (3,4,5,6,7,8).
We have identified a number of cold-induced transcription factors that have a potential role in configuring the low temperature
transcriptome. T-DNA insertion and overexpression lines of these plants are being tested to identify their function in the cold acclimation
response. We are building a gene regulatory network of transcriptional changes that occur in Arabidopsis during cold acclimation.
Preliminary analysis indicates that the transcriptional response to cold acclimation is robust with considerable co-regulation of targets.
(a) Michigan State University
M2002 Sugar-regulated gene expression and the control of seed oil synthesis in Arabidopsis
Nakamura, Kenzo-presenter [email protected](a)
Changes in sugar nutritional status of the cell modulate the expression of a large number of plant genes. We used the sGsL line of
Arabidopsis thaliana expressing a LUC reporter gene with a short sugar-inducible promoter to identify genes that control expression of
sugar-inducible genes. One of the enhancer tagged mutant of sGsL, with enhanced expression of LUC reporter and several endogenous
sugar-inducible genes, was due to enhanced expression of ASML1/WRINKLED1 (WRI1) encoding an AP2-type transcription activator
required for seed oil accumulation. We identified direct targets of WRI1 and the WRI1 binding sequence designated as AW box. More than
20 genes involved in fatty acid synthesis in plastids were direct targets of WRI1, and the AW box in the proximal promoter regions of at
least two of them was required for their expression during seed maturation. These results suggest that WRI1 controls carbon flow from
sucrose import to lipid synthesis in developing seeds. In contrast to fatty acid synthesis in plastids, enhanced expression of WRI1 was not
sufficient for activation of genes involved in triacylglycerol synthesis and oil body formation in the ER, despite their expression during seed
maturation required WRI1. The hsi2 mutant of sGsL with high-level LUC expression under low-sugar condition was due to nonsense
mutation in a gene for B3 domain-EAR transcriptional repressor. Seeds with disruption of both HSI2 and HSL1 (HSI2-like 1) developed
abortive seedlings that expressed seed maturation genes including WRI1 and genes for oil synthesis in a sugar-dependent manner. Our
results suggest that HSI2 and HSL1 are essential to repress the expression of seed maturation genes in seedlings.
(a) Lab. Biochem., Grad. Sch. Bioagr. Sci., Nagoya Univ.
M2003 Mutator transposition alters the transcriptome and proteome of developing maize anthers
Skibbe, David S-presenter [email protected](a)
Fernandes, John F (a)
Morrow, Darren J (a)
Medzihradszky, Katalin F
(b)
Burlingame, Alma L (b)
Walbot, Virginia (a)
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PB 2008
MuDR/Mu are a highly active transposon family moving by either cut only (or cut-and-paste) in strictly somatic tissues or net replicative
transposition (absence of excision alleles) in reproductive tissues. Aside from the MuDR-encoded MURA and MURB proteins, other factors
required for Mu transposition, particularly those contributing to the developmentally specific behavior, have yet to be identified. To address
this question and assess the impact of a highly active transposon on the transcriptome and proteome, RNA and protein was extracted from
anthers at three developmental stages in Mu-active and -inactive stocks. From transcriptome profiling on a 44,000 element oligonucleotide
array we found that approximately 30,000 unique genes are expressed at each stage. Of the ~10% (ca. 3000) differentially regulated
transcripts per stage, there was approximately equal representation by the active or inactive individuals. The effect of Mutator activity on
the host proteome was determined using 2D-Difference Gel Electrophoresis. Of the approximately 2,500 protein spots visualized, Mu-active
and -inactive individuals exhibited 48 statistically significant differentially regulated spots. In contrast to the transcriptome experiments, 47
of the 48 spots were up-regulated in the Mu-active lines. Peptides in 30 spots were sequenced, and the majority encoded genes with
metabolic functions. Twenty-one of these 30 were represented on the oligonucleotide array, and twenty were up-regulated at both the RNA
and protein levels. Interestingly, transcriptome profiling experiments comparing Mu-active lines with or without Mukiller identified unique
sets of differentially expressed genes, suggesting non-equivalence between the silenced state arising spontaneously and induced by
Mukiller.
(a) Stanford University, Department of Biology (b) University of California, San Francisco, Department of Pharmaceutical Chemistry
M2003 Mutator transposition alters the transcriptome and proteome of developing maize anthers
Skibbe, David S-presenter [email protected](a)
Fernandes, John F (a)
Morrow, Darren J (a)
Medzihradszky, Katalin F
(b)
Burlingame, Alma L (b)
Walbot, Virginia (a)
MuDR/Mu are a highly active transposon family moving by either cut only (or cut-and-paste) in strictly somatic tissues or net replicative
transposition (absence of excision alleles) in reproductive tissues. Aside from the MuDR-encoded MURA and MURB proteins, other factors
required for Mu transposition, particularly those contributing to the developmentally specific behavior, have yet to be identified. To address
this question and assess the impact of a highly active transposon on the transcriptome and proteome, RNA and protein was extracted from
anthers at three developmental stages in Mu-active and -inactive stocks. From transcriptome profiling on a 44,000 element oligonucleotide
array we found that approximately 30,000 unique genes are expressed at each stage. Of the ~10% (ca. 3000) differentially regulated
transcripts per stage, there was approximately equal representation by the active or inactive individuals. The effect of Mutator activity on
the host proteome was determined using 2D-Difference Gel Electrophoresis. Of the approximately 2,500 protein spots visualized, Mu-active
and -inactive individuals exhibited 48 statistically significant differentially regulated spots. In contrast to the transcriptome experiments, 47
of the 48 spots were up-regulated in the Mu-active lines. Peptides in 30 spots were sequenced, and the majority encoded genes with
metabolic functions. Twenty-one of these 30 were represented on the oligonucleotide array, and twenty were up-regulated at both the RNA
and protein levels. Interestingly, transcriptome profiling experiments comparing Mu-active lines with or without Mukiller identified unique
sets of differentially expressed genes, suggesting non-equivalence between the silenced state arising spontaneously and induced by
Mukiller.
(a) Stanford University, Department of Biology (b) University of California, San Francisco, Department of Pharmaceutical Chemistry
M2004 P-bodies and ARE-mediated post-transcriptome in plants
Jang, JC-presenter [email protected](a,b)
Lin, Pei-Chi (a,c)
Pomeranz, Marcelo (a,b)
Kang, Shin-Gene (a,b)
Hah, Cyrus (a,b)
P-bodies are cytoplasmic foci where mRNP (mRNA ribonucleoprotein complex), miRNP (microRNA associated RNP), and siRNP (small
interfering RNA associated RNP) aggregate and execute gene silencing via mRNA decay and translation repression. In the AU rich elements
(ARE) mediated mRNA decay pathway, zinc finger proteins serve as key regulators in P-body formation, RNA binding, and recruitment and
activation of de-capping, de-adenylation, and exonucleolytic enzymes. In rice and Arabidopsis, we have identified a family of zinc finger
proteins that localize to cytoplasmic foci resembling P-bodies. The zinc finger domains share similarity to the mammalian counterparts but
distinct enough to form unique patterns that can only be found in plant kingdom. They co-localize with AGO, DCP, and XRN that are
constituents of P-bodies. While there are no apparent loss-of-function phenotypes in single gene knockout plants, ectopic expression causes
dramatic changes in growth and development from single cell to whole plant level, implicating their critical roles in gene expression. We
have identified a set of genes that contain consensus ARE in the 3-UTR where the zinc finger proteins can bind in vitro. Global gene
expression profiling reveals that these zinc finger genes may play pivotal role in mRNA stability control. A model is proposed for the role of
these zinc finger proteins in mRNP and plant post-transcriptome.
(a) Plant Biotech Center, Ohio State University (b) Horticulture and Crop Science, Ohio State University (c) Plant Cellular and Molecular
Biology, Ohio State University
Date
TUESDAY
July 1
Start
8:30 AM
End
Minisymposium
Location
10:10 AM Minisymposium 21 – Seed Biology – Chair: Jeff Shen
Siglo XXI Convention Center 8:30 - M2101: Woei-Jiun Guo - An ABA/Stress-Induced HVA22 Salon Izamal
Protein Inhibits GA-Induced Programmed Cell Death in
Aleurone Cells
8:55 – Abstract 2102: Russell Johnson - The wheat PKABA1interacting factor TaABF1 mediates both abscisic acidsuppressed and abscisic acid-induced gene expression in
aleurone cells
9:20 - M2103: Ljudmilla Borisjuk - Functional analysis of the
plastidial glucose-6-phosphate/phosphate translocator in
legume seeds suggests a role for cellular differentiation and
storage control
9:45 – Abstract 2104: Daniel Vernon - Diverse impacts of PPR
knockout mutations on Arabidopsis embryo morphology, cell
organization, and plastid development
77
M2101 An ABA/Stress-Induced HVA22 Protein Inhibits GA-Induced Programmed Cell Death in Aleurone Cells
Guo, Woei-Jiun-presenter [email protected](a)
Ho, Thun-Hua David (a)
Plant HVA22 is a unique type of ABA/stress-induced protein in seeds, which was first isolated from barley (Hordeum vulgare) aleurone cells.
Its yeast homolog, Yop1p, has been shown to regulate vesicular trafficking and to comprise ER network in vivo. However, physiological
roles of HVA22 in plants remain unclear. To further examine the roles of plant HVA22, HvHVA22 was ectopically expressed in barley
aleurone cells. Overexpression of HvHVA22 proteins inhibited GA-induced formation of large digestive vacuoles, which is an important
aspect of programmed cell death in aleurone cells. The effect of HvHVA22 was specific because overexpression of GFP or another ABAinduced protein, HvHVA1, did not lead to the same effect. The action of HVA22 was downstream of the transcription factor GAMyb whose
GA-induced synthesis is antagonized by ABA. Moreover, expression of HvHVA22:GFP fusion proteins showed network and punctate
fluorescence patterns, which were colocalized with an ER marker, Bip:RFP, and a Golgi marker, ST:mRFP, respectively. All the three
potential transmembrane domains were required for HvHVA22 function, with transmembrane domain 2 being critical for the stability of this
protein. Ectopic expression of the most phytogenetically similar Arabidopsis homolog, AtHVA22D, also resulted in inhibition of vacuolation to
a similar level as HvHVA22, indicating function conservation between some Arabidopsis and barley HVA22 proteins. Taken together, our
data show that HvHVA22 is an ER and Golgi-localized membrane protein capable of negatively regulating GA-mediated programmed cell
death in barley aleurone cells. We propose that HvHVA22 inhibits vesicular trafficking to delay coalescence of protein storage vacuoles.
(a) Institute of Plant and Microbial Biology, Academia Sinica
M2102 The wheat PKABA1-interacting factor TaABF1 mediates both abscisic acid-suppressed and abscisic acid-induced
gene expression in aleurone cells
Johnson, Russell R-presenter [email protected](a)
Kaung, Aung (a)
Savic, Talia (a)
Shin, Margaret (b)
Shen, Jeff Q (b)
The hormones abscisic acid (ABA) and gibberellin (GA) have opposing effects in imbibing cereal grains. To investigate the crosstalk of ABA
and GA signaling in wheat (Triticum aestivum), we have focused on the transcription factor TaABF1. TaABF1 (a member of the ABA
response element binding factor family) physically interacts with PKABA1, a signaling component in the ABA-suppression of GA-induced
gene expression in cereal grains. Constitutive expression of TaABF1 in aleurone cells of imbibing grains completely eliminated GA-induced
expression from the Amy32b promoter. In addition to its effect on Amy32b, TaABF1 strongly stimulated expression from the ABA-inducible
HVA1 and HVA22 promoters. Overexpression of TaABF1 fully substituted for exogenous ABA in the induction of these two promoters.
Although TaABF1 mRNA is downregulated during imbibition of afterripened grains, transcript levels were not significantly altered by
exogenous GA or ABA, suggesting that upregulation of TaABF1 at the mRNA level is not required for its role in ABA signaling. We
hypothesize that TaABF1 may be regulated by ABA at the protein level. We are currently investigating the effects of ABA on the
phosphorylation, stability, and abundance of TaABF protein in order to determine the mechanism by which ABA leads to TaABF1 activation
during grain imbibition.
(a) Colby College (b) University of Nevada, Las Vegas
M2103 Functional analysis of the plastidial glucose-6-phosphate/phosphate translocator in legume seeds suggests a role
for cellular differentiation and storage control
Borisjuk, Ljudmilla-presenter [email protected](a)
Rolletschek, Hardy (a)
Nguyen, Ha (a)
Haeusler, Rainer
(b)
Wobus, Ulrich (a)
The glucose-6-phosphate/phosphate translocator (GPT) imports carbon into the plastid. Its regulatory role in biosynthetic pathways active
during seed development is poorly understood. We have isolated GPT1 from pea (Pisum sativum), and analysed its functional role for
storage and differentiation in seeds. GPT1 was highly expressed in vegetative sink tissues, flowers and young seeds. Its localised upregulation coincided with the onset of starch accumulation. Using a transgenic approach, GPT1 was expressed in either sense or antisense
orientation under control of the seed-specific LeB4-promoter. Embryos of transgenic plants expressing antisense GPT1 showed a significant
reduction up to 55% in the specific transport rate of Gluc6P. Amyloplast development was decelerated. Metabolite analysis and stable
isotope labelling demonstrated that starch biosynthesis was reduced, although storage protein biosynthesis increased. This metabolic shift
was characterized by an up-regulation of genes related to nitrogen uptake and protein storage, and an up to 30% higher crude protein
content of mature seeds of transgenics. In opposite, embryos of transgenic plants overexpressing GPT1 reached higher biomass as
compared to WT and showed an increase in starch content by 30%. Protein content was not affected. Metabolic changes were accompanied
by higher expression of sucrose transporter1 (SUT1) in transgenics versus WT. We conclude that (1) the prevailing level of GPT1
abundance/activity is rate-limiting for the synthesis of starch in developing seeds, (2) GPT1 exerts a controlling function for assimilate
partitioning into storage protein, and (3) GPT1 is essential for the differentiation of embryonic plastids and seed maturation.
(a) ipk (b) university cologne
M2104 Diverse impacts of PPR knockout mutations on Arabidopsis embryo morphology, cell organization, and plastid
development.
Vernon, Daniel M.-presenter [email protected](a,b)
Davis, Nick A (a)
Forsthoefel, Nancy R (a)
Pentatricopeptide Repeat proteins (PPRs) constitute one of the largest superfamilies in plants, with more than 440 identified in Arabidopsis.
While some PPRs are known to take part in post-transcriptional steps of mitochondrial and plastid gene expression, little is known about the
broader biological contexts of PPR gene function. We previously identified a subset of Arabidopsis PPR genes, EMB-PPRs, that are essential
for normal embryogenesis and morphological development. To better understand PPR functions in early development, we investigated the
impacts of knockout mutations in two EMB-PPR genes, here designated as EMB-PPR2 and EMB-PPR3. The embryonic functions of these
genes were confirmed with second alleles, and RT-PCR confirmed that both mutations were full knockouts. Mutant embryos had dramatic
morphological defects, including stunted cotyledons and enlarged shoot apices. Histological analysis revealed abnormal cell shape and
organization in mutant cotyledons; defects were more severe in emb-ppr2. TEM of cotyledons indicated that proplastid development and
thylakoid formation were arrested to a different degree in each mutant, establishing plastid function for both EMB-PPR2 and EMB-PPR3.
Altered expression of nuclear genes encoding proteins with diverse plastid functions was demonstrated by quantitative RT-PCR, and levels
of photosynthesis-related mRNAs were dramatically reduced. Taken together, these results reveal that EMB-PPR2 and EMB-PPR3 are critical
at different stages of embryonic plastid development and that these genes have distinct impacts on supracellular aspects of development,
including cell organization, organogenesis, and embryo morphology. These mutants underscore the importance of plastids in embryogenesis
78
PB 2008
and provide a system for further investigation of plastid maturation and PPR gene functions in early plant development. Supported by NSF
award 0616166 to D.M.V
(a) Biology Department, Whitman College (b) Program in Biochemistry, Biophysics & Molecular Biology, Whitman College
Date
TUESDAY
July 1
Start
8:30 AM
End
Minisymposium
Location
10:10 AM Minisymposium 22 – Phytoremediation – Chair: Sharon L. Siglo XXI Convention Center Doty
Salon Progreso
8:30 - M2201: Sharon L. Doty - Enhancing Phytoremediation of
A Variety of Organic Pollutants
8:55 – Abstract 2202: Elizabeth Pilon-Sm+C100its - Plant
Selenium Hyperaccumulation Functions as a Defense Against
Herbivory
9:20 – Abstract 2203: Usha Balasundaram - A nucleocytoplasm co-localized type 2 metallothionein from Prosopis
juliflora confers heavy metal tolerance to transgenic tobacco
9:45 – Abstract 2204: David G. Mendoza-Cozatl -
Characterization of the thiol-peptides in the phloem sap of
Brassica napus and their role in the long-distance transport of
cadmium
M2201 Enhancing Phytoremediation of A Variety of Organic Pollutants
Doty, Sharon L.-presenter [email protected](a)
James, Andrew (a)
Vajzovic, Azra (a)
Singleton, Glenda (a)
Kang,
JunWon (a)
Lee, KeumYoung (a)
Zhang, Gengyun (a)
Bruce, Neil (b)
Schuler, Mary (c)
Strand, Stuart E. (a)
http://faculty.washington.edu/sldoty
Halogenated hydrocarbons, such as trichloroethylene (TCE), are serious environmental contaminants of soil, groundwater, and air. Studies
of the metabolism of this class of pollutants by poplar trees, a genus widely used in phytoremediation applications, has demonstrated that
cytochrome P450 enzymes are involved in the early steps of TCE metabolism. Using microarrays of poplar and Arabidopsis, we have
determined a number of genes that are differentially regulated in response to TCE. Through overexpression of candidate genes and RNAi
experiments in Arabidopsis, we hope to elucidate which of these genes may be directly involved in TCE metabolism. Transgenic plants that
express the genes necessary to metabolize pollutants could lead to profound enhancements in phytoremediation. We have developed
transgenic poplar plants with greatly increased rates of metabolism and removal of these pollutants through the overexpression of
cytochrome P450 2E1. The transgenic poplar plants exhibited increased removal rates of these pollutants from hydroponic solution. When
the plants were exposed to gaseous TCE, chloroform, and benzene, they also demonstrated superior removal of the pollutants from the air.
In view of their large size and extensive root systems, these transgenic poplar may provide the means to effectively remediate sites
contaminated with a variety of pollutants at much faster rates and at lower costs than can be achieved with current conventional
techniques. Another important class of environmental pollutants is the nitroaromatic explosives including TNT and RDX. Expression of
bacterial genes involved in the metabolism of these pollutants in transgenic Arabidopsis, poplar, and grasses led to increased tolerance and
removal rates of TNT and RDX by the transgenic plants.
(a) University of Washington (b) University of York (c) University of Illinois
M2202 Plant Selenium Hyperaccumulation Functions as a Defense Against Herbivory
Pilon-Smits, Elizabeth A-presenter [email protected](a)
Freeman, John L (a)
Quinn, Colin F (a)
Galeas, Miriam L (a)
The element selenium (Se) is essential for many organisms but toxic at higher levels. Hyperaccumulator plants like Astragalus and Stanleya
can accumulate Se up to 1% of their dry weight. Our results from a range of lab and field experiments indicate that Se hyperaccumulation
can protect plants against herbivory, due to both deterrence and toxicity. Many invertebrate herbivores (aphids, spidermites, thrips,
grasshoppers, crickets, caterpillars) are deterred by Se-rich plants and suffer toxicity when they feed on them; Se also deters prairie dog
herbivory. Hyperaccumulators contain most Se in leaf hairs and epidermis of young leaves and reproductive tissues, typical for defense
compounds. Moreover, hyperaccumulators harbored fewer invertebrates than non-hyperaccumulators in the field, and fewer invertebrate
species. Some of the herbivores that were found feeding on hyperaccumulators in the field appear to be specialists. They are Se-tolerant
and accumulate levels of Se that likely affect higher trophic levels. Biochemical studies on Se-tolerant herbivores suggest their tolerance
mechanism is exclusion of Se from proteins, similar to their plant host. One Se-tolerant herbivore, a diamondback moth, was found to
harbor a Se-tolerant parasitic wasp, suggesting a higher trophic level adaptation. In conclusion, while Se accumulation protects plants from
generalist herbivores, some specialist herbivores have evolved resistance, as have some of their parasites, potentially forming a portal for
Se into the local ecosystem. These results give insight into the functional significance of Se hyperaccumulation and may have implications
for use of Se-accumulating plants for phytoremediation or as fortified food.
(a) Colorado State University
M2203 A nucleo-cytoplasm co-localized type 2 metallothionein from Prosopis juliflora confers heavy metal tolerance to
transgenic tobacco
Balasundaram, Usha-presenter [email protected](a)
Venkataraman, Gayatri (a)
Parida, Ajay (a)
http://www.mssrf.res.in
Metallothioneins (MTs) are small cysteine rich proteins that bind heavy metals like Cu, Cd and Zn. Their overexpressions has proven to be a
successful strategy for enhancing heavy metal tolerance and are potential candidate genes for generation of transgenic plants for
phytoremediation, thus facilitating cultivation in marginal metal-polluted soils. Over-expression of type 2 MT, (PjMT2), from Prosopis
juliflora, a heavy metal accumulating phreatophyte, increased the accumulation of cadmium in transgenic tobacco by five fold without
significantly affecting zinc accumulation. In addition, transgenic tobacco showed greater tolerance to oxidative stress. PjMT2 bound to
cadmium with higher affinity than zinc even in E. coli cells expressing the PjMT2::GST fusion protein. These results indicate that PjMT2
79
confer increased heavy metal tolerance in transgenic plants and bacterial systems. Expression pattern of PjMT2 revealed that it is induced
by Zn and H2O2 treatments. Promoter region of PjMT2 revealed the presence of TATA, CAAT and GATA boxes. ABA responsive elements
were found in the promoter and PjMT2 was found to be induced under ABA treatment. Confocal microscopy of tobacco plants expressing
PjMT2::mGFP6 fusion protein showed that PjMT2 co-localized in the cytoplasm and nucleus. Information on the site of action of MT2 in the
plant cell would give an idea of its function in vivo. Nuclear localization gives a clue that like animal MT2 genes, plant MTs may also play an
important role during cell proliferation. A detailed validation of nuclear specific localization of MT2 in plants may decipher its role other than
metal homeostasis.
(a) M.S.Swaminathan Research Foundation
M2204 Characterization of the thiol-peptides in the phloem sap of Brassica napus and their role in the long-distance
transport of cadmium
Mendoza-Cozatl, David G-presenter [email protected](a)
Butko, Emerald (a)
Springer, Franziska (b)
Kehr, Julia (b)
Komives,
Elizabeth (c)
Schroeder, Julian (a)
Phytochelatins (PCs) are glutathione-derived peptides that function in heavy metal detoxification in plants and other organisms. Recent
research in Arabidopsis has shown that PCs undergo long-distance transport between roots and shoots (Gong et al., 2003 PNAS 100:10118;
Chen et al., 2006 Plant Physiol 141:108). However, it remains unknown which vascular system, xylem or phloem, mediate PC translocation
and whether PC transport contributes to physiologically relevant long-distance transport of cadmium (Cd) between shoots and roots. To
address these questions, xylem and phloem sap were obtained from Brassica napus to quantitatively analyze which thiol species are present
in response to Cd exposure. High levels of PCs were identified in the phloem sap within 24 hours of Cd exposure using combined mass
spectrometry and fluorescence HPLC analyses. Unexpectedly, the concentration of Cd was more than 4-fold larger in phloem sap compared
to xylem sap. Cd exposure dramatically decreased iron levels in xylem and phloem sap whereas other essential heavy metals such as zinc
and manganese remained unchanged. The high ratios [PCs]/[Cd] and [glutathione]/[Cd] in the phloem sap suggest that PCs and
glutathione (GSH) can function as long distance carriers of Cd. In contrast, only traces of PCs were detected in xylem sap. Our results
suggest that, in addition to directional xylem Cd transport, the phloem functions as a major vascular system for long-distance source to sink
transport of Cd as PC-Cd and glutathione-Cd complexes. Size-exclusion chromatography of the phloem sap to establish the amount of
cadmium bound to the different types of thiol-containing peptides will also be presented. Supported by NIH grant to JIS and EAK. DMC is a
PEW Latin American Fellow 2006
(a) Biological Sciences, University of California, San Diego (b) Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany (c)
Department of Biochemistry, University of California, San Diego
Date
TUESDAY
July 1
Start
End
8:30 AM
Minisymposium
10:10 AM Minisymposium 23 – Photosynthesis – Chair: John
Cushman
8:30 - M2301: Steven Rodermel - Suppressors of the var2
Location
Siglo XXI Convention Center Salon Valladolid
variegation mutant of Arabidopsis provide access to regulatory
networks that govern chloroplast biogenesis
8:55 - M2301: Aleel K. Grennan - Role of pheophorbide a
oxygenase in chlorophyll degradation
9:20 - M2303: Ruey-hua Lee - Alkaline α-galactosidase
degrades thylakoid membranes in the chloroplast during rice
leaf senescence
9:45 - M2304: Katia Silvera - Crassulacean Acid Metabolism in
tropical orchids: integrating isotopes, habitat preference and
gene expression
M2301 Suppressors of the var2 variegation mutant of Arabidopsis provide access to regulatory networks that govern
chloroplast biogenesis
Rodermel, Steven-presenter [email protected](a)
Yu, Fei (a)
Liu, Xiayan (a)
Xu, Yang (a)
Undifferentiated proplastids in the apical meristem are converted into photosynthetically-competent chloroplasts early in leaf development.
We are using Arabidopsis var2 variegation mutants as a tool to gain entrance into the mechanisms that regulate chloroplast development.
These mutants contain green- and white-sectored leaves due to the action of a nuclear recessive gene; all the tissues of the mutant have a
uniform (mutant) genetic constitution, but only the white sectors have a mutant phenotype. VAR2 codes for an FtsH metalloprotease that is
anchored in the thylakoid membrane as part of a larger AtFtsH complex. It mediates turnover of the D1 protein of PSII and thus plays a
central role in photoprotection. VAR2 has also been implicated in a number of other chloroplast processes, but little is understood about the
molecular details. To better understand the function of VAR2 and the mechanism of var2 variegation, we have carried out second-site
suppressor screens of var2 using EMS and activation tagging mutagenesis. Over 100 loss-of-function and gain-of-function suppressor lines
with non-variegated phenotypes have been isolated. The suppressor genes in five of these lines have been cloned and characterized. These
genes code for known components of the chloroplast, as well as several novel proteins with previously unknown functions. The latter
include a protein that associates with PSI and is essential for growth and development. To describe the interactions between VAR2 and its
suppressors we have constructed a Genetic Interactions Network. This network provides insight into mechanisms of var2 variegation and
chloroplast biogenesis. In our presentation we will describe the cloning results and our genetic network.
(a) Iowa State University
M2302 Role of pheophorbide a oxygenase in chlorophyll degradation
Chung, Davyd W (a)
Grennan, Aleel K-presenter [email protected](a)
Ort, Donald R (b,a)
http://www.life.uiuc.edu/ort/
Degradation of chlorophyll (Chl) is a developmentally regulated cellular process usually related with leaf senescence and fruit ripening. In
80
PB 2008
the plastid of senescing leaves, photoactive Chl is catabolized in a stepwise manor to yield fluorescent chlorophyll catabolites (FCCs). FCCs
are then exported from the plastid and ultimately to the vacuole where the acidic pH converts them to colorless breakdown products
(NCCs). A key enzyme in the Chl degradation process is the Fe-dependent monooxygenase pheophorbide a oxygenase (PaO), which is
responsible for the conversion of Pheide a to red colored catabolite (RCC). The regulation of PaO, a known key regulator of Chl loss, has
recently been studied in canola (Brassica napus) seeds where it was shown to be posttranslationally regulated by a phosphorylation/
dephosphorylation mechanism. A comparative study on the role of PaO in the leaf systems of Arabidopsis (Arabidopsis thaliana) and canola
in respect to Chl loss as well as further characterization of PaO through mutant analysis using RNAi has been undertaken. We also describe
additional posttranslational modifications, more specifically, the in vitro interaction of PaO and CDPK.
(a) University of Illinois (b) USDA/Agricultural Research Service
M2303 Alkaline α-galactosidase degrades thylakoid membranes in the chloroplast during rice leaf senescence
Lee, Ruey-hua-presenter [email protected](a)
Hao-Jen , Huang (a)
The breakdown of thylakoid membranes plays a vital role for structure and stability of photosynthetic complexes during leaf senescence.
OsAkαGal encodes a chloroplast alkaline α-galactosidase in rice. In our current work, we assayed the enzyme activity of recombinant
OsAkαGal with different natural substrates and examined the effect of ectopic OsAkαGal expression in rice plants. OsAkαGal showed
substrate preference to the galactolipid DGDG. The OsAkαGal null mutant displayed a delayed leaf senescence phenotype. OsAkαGal
complementation recovered OsAkαGal expression and a senescence phenotype similar to that of wild-type plants. In contrast, OsAkαGal
overexpression (UbiP-OsAkαGal) resulted in a pale green phenotype coupled with total chlorophyll content reduced to 42% in the newly
unfolded leaves. UbiP-OsAkαGal plants also exhibited retarded plant growth and development. These plants took twice as much time to
flower and set seeds as wild-type plants. Furthermore, UbiP-OsAkαGal leaves also showed a 29-fold increase in alkaline galactosidase
activity as compared with wild-type leaves. An ultrastructural study of Ubi-OsAkαGal chloroplasts in newly unfolded leaves revealed
abnormal grana organization, with organized thylakoid stacks rarely found. Most of the thylakoids became degraded or were dilated. Our
findings strongly suggest that OsAkαGal is a thylakoid membrane-degrading enzyme involved in the degradation of DGDG during rice leaf
senescence.
(a) Department of Life Sciences, National Cheng Kung University,
M2304 Crassulacean Acid Metabolism in tropical orchids: integrating isotopes, habitat preference and gene expression.
Silvera, Katia-presenter [email protected](a,d)
Santiago, Louis S. (b)
Rodriguez, Leticia (a)
Whitten, Mark (c)
Williams,
Norris H. (c)
Neubig, Kurt M. (c)
Winter, Klaus (d)
Cushman, John C. (a)
Crassulacean Acid Metabolism (CAM) is a water-conserving mode of photosynthesis present in 7% of vascular plant species worldwide. In
tropical orchids, CAM expression is found in up to 50% of species. We used stable carbon isotopic composition from leaf samples to survey
the occurrence of CAM in orchids. Carbon isotopic composition of leaf material of 1,100 orchid species showed a bimodal distribution with
peak values near -27 per mil indicating C3 photosynthesis, or around -15 per mil, indicating CAM photosynthesis. Titratable acidity
measurements of species within the C3 photosynthesis peak revealed up to 30% species with a weak CAM capacity. When CAM is overlain
onto a molecular phylogeny of orchids, the distribution of photosynthetic pathways showed that C3 photosynthesis is the ancestral state and
that CAM has evolved more than once within the Orchidaceae. CAM is also correlated with growth forms. Out of 826 orchid species, we
found that CAM is present only in epiphytes, and it is predominantly found in drier sites. High quality leaf RNA samples were obtained from
closely related orchid species from the subtribe Oncidiinae with a range of photosynthetic pathways from C 3 photosynthesis to weak or
strong CAM. Analysis of the phosphoenolpyruvate carboxylase (PEPC) gene family structure and mRNA relative abundance revealed that at
least five isoforms are present in orchids, with one putative distinct CAM-specific PEPC isogene identified in CAM and weak CAM species
based on cDNA clone sampling. This interdisciplinary project integrates ecophysiological, biochemical and molecular genetic approaches to
understand the evolutionary origins of CAM within the context of a highly resolved phylogeny of orchids.
(a) University of Nevada Reno, Department of Biochemistry & Molecular Biology, MS/200, 1664 N Virginia St, Reno, NV 89557-0014 (b)
University of California Riverside, Department of Botany and Plant Sciences, 2150 Batchelor Hall, Riverside, CA, 92521 (c) University of
Florida, Florida Museum of Natural History, Gainesville, FL 32611-7800 (d) Smithsonian Tropical Research Institute, P.O. Box 0843-03092,
Balboa, Ancon, Republic of Panama
Date
TUESDAY
July 1
Start
10:40 AM
End
Minisymposium
12:20 PM Minisymposium 24 – Plant Biotechnology – Chair: Yi Li
10:40 - M2401: Elsbeth Walker - C103TcJAMYC: a
transcriptional regulator of paclitaxel (TaxolTM) biosynthesis in
cultured Taxus cells
11:05 - M2402: Yi Li - Gene-deletor: a tool to eliminate all
transgenes in pollen and seed when their functions are no
longer needed or their presence can cause concerns
11:30 - M2403: Rima Menassa - Trafficking, degradation and
purification of recombinant IL-10 protein in plants
11:55 - M2404: Qungang Qi - Biochemical Characterization and
Mutational Analysis of Aspartate Kinases to Identify Feedbackresistant Variants and Seed-specific Over-expression of the
Variants for Enhanced Threonine Levels in Soybean Seed
Location
Siglo XXI Convention Center Salon Merida
M2401 TcJAMYC: a transcriptional regulator of paclitaxel (TaxolTM) biosynthesis in cultured Taxus cells
Walker, Elsbeth L-presenter [email protected](a)
Nims, Zeke (b)
Roberts, Susan (c)
Methyl jasmonate (MJ) is highly effective at eliciting secondary metabolite accumulation in a variety of plant cell culture systems.
Accordingly, accumulation of the anti-tumor agent paclitaxel (TaxolTM) in cultured cells is significantly enhanced with MJ elicitation. A wellconserved basic helix-loop-helix protein (bHLH), JAMYC, regulates gene expression changes that occur following MJ application in
81
Arabidopsis (AtMYC2) and potato (JAMYC2 and JAMYC10). JAMYCs bind directly to promoters of genes involved in defense, and activate
transcription of these genes. Although Taxus is evolutionarily distant from the angiosperm species in which JAMYCs have been
characterized, we were able to use degenerate primers to amplify a gene with strong sequence similarity to JAMYC (TcJAMYC) from Taxus
cuspidata P991 cells. We cloned promoters of several Taxus genes that encode enzymes in paclitaxel biosynthesis, and which are induced
strongly following MJ elicitation, and find that potential TcJAMYC binding sites are over-represented within them. We have used the
promoters of the biosynthetic genes to make reporter constructs, and, using transient expression assays, have shown that all the promoters
used (T5alphaH, DBAT, PAM, BAPT, and DBTNBT) confer MJ-inducible expression on the reporter. Using co-expression experiments, we
have further demonstrated that TcJAMYC is capable of activating transcription of most of the paclitaxel biosynthetic gene promoters tested,
but not of all of them. Thus, our experiment support the idea that TcJAMYC is a master regulator of paclitaxel biosynthesis, but that
additional unknown regulatory factors must also be involved.
(a) Department of Biology, University Of Massachusetts (b) Plant Biology Graduate Program, University of Massachusetts (c) Department of
Chemical Engineering, University Of Massachusetts
M2402 Gene-deletor: a tool to eliminate all transgenes in pollen and seed when their functions are no longer needed or
their presence can cause concerns.
Li, Yi-presenter [email protected](a)
Duan , Hui (b)
Keming, Luo (c)
Pollen- and seed-mediated transgene flow is a serious concern in plant biotechnology. We have recently developed a highly efficient gene
deletion system to automatically remove all functional transgenes from both pollen and seed. With three pollen- and/or seed-specific gene
promoters tested, the phage CRE/loxP or yeast FLP/FRT recombinase system alone produced no transgenic event that were 100% efficient
in excising transgenes from tobacco pollen and/or seed. When loxP-FRT fusion sequences were used as recognition sites, simultaneous
expression of both FLP and CRE reduced the average excision efficiency. However, with the loxP-FRT as the recognition sequences,
expression of FLP or CRE alone led to increases in the average excision efficiency, with many transgenic events being 100% efficient based
on more than 25 000 T1 progeny examined per event. We named this system as ‗gene-deletor.‘ If the ‗gene-deletor‘ is modified, the system
may be used to produce non-transgenic seed, fruit or other edible organs from transgenic plants when functions of transgenes are no
longer needed or their presence may cause concerns. The technology may provide a useful tool to address pollen- and seed-mediated
transgene flow problems and also food safety concerns over transgenic crops. For more information, please Google ―gene-deletor‖.
(a) University of Connecticut (b) University of Illinois (c) Michigan Technological University
M2403 Trafficking, degradation and purification of recombinant IL-10 protein in plants
Menassa, Rima-presenter [email protected](a)
Kaldis, Angelo (a)
Many therapeutic proteins have been expressed in plants with varying levels of accumulation. Two major challenges for economical
production of recombinant proteins include inadequate accumulation levels and the lack of efficient purification methods. Our research has
focused on addressing these issues using the human interleukin-10 protein (IL-10) which has been proposed for the treatment of several
autoimmune diseases. It is a labile protein with a half-life in vivo of 30 minutes, requiring post-translational modifications and assembly. We
have previously shown that plant recombinant IL-10 is biologically active and is therapeutic when administered orally in a mouse model of
colitis. However, IL-10 does not accumulate in plants to levels that would allow human clinical trials to be conducted. We have approached
this problem from several angles, including a cell biology approach to its trafficking in plant cells with GFP fusions, a biochemistry approach
to determine the turnover rate and mechanism of IL-10 degradation, a protein chemistry approach to determine post-translational
modifications and processing sites, and a biotechnological approach to improve accumulation levels of IL-10 in plants and to allow for easy
purification of the recombinant protein. Through these approaches we have enhanced expression levels of IL-10 by up to 60 fold, and
determined that unexpected trafficking to the vacuole may play a role in its turnover. Further, we identified several isoforms of IL-10 which
migrate at different pI values from 7.5 to 9 probably because of a combination of deamidation, oxidation of methionines, and substitution of
cysteines for dehydroalanines. These results and their implications for the production of recombinant proteins in plants will be discussed.
(a) Agriculture and Agri-Food Canada
M2404 Biochemical Characterization and Mutational Analysis of Aspartate Kinases to Identify Feedback-resistant Variants
and Seed-specific Over-expression of the Variants for Enhanced Threonine Levels in Soybean Seed
Qi, Qungang-presenter [email protected](a)
Ruschke, Lisa (a)
Goldman, Barry S. (a)
Huang, Jintai (a)
Wen, Li
(a)
Crowley, James H. (a)
Rapp , William D. (a)
Threonine is an essential amino acid in the animal feed industry and its levels in feed rations can impact production of important meat
sources, such as swine and poultry. Threonine as well as essential amino acids lysine and methionine are all synthesized via the aspartate
family pathway. Aspartate kinase (AK) is the first enzyme in the pathway, and catalyzes the ATP-dependent phosphorylation of aspartate to
form β-aspartyl phosphate. AK constitutes the main regulatory step controlling the metabolic flux through the pathway, and is subject to
end product inhibition by Lys and/or Thr. Here we report that a successful strategy has been developed to produce high free threonine
soybean seed via identification of feedback-resistant AK enzymes in the aspartate family pathway. To further elucidate the mechanism for
the feedback inhibition of AK, we mapped the catalytic and regulatory domains. Mutant alleles were subjected to steady-state kinetic
analysis, and the kinetic parameters of these purified mutant alleles and wild-type genes were presented. Seed-specific expression of sitedirected mutant alleles has resulted in up to 100-fold increase in threonine level of R1 soy seed, compared to wild-type. These results
suggest the utility of the deregulated AK in enhancing plant nitrogen metabolism and crop growth performance.
(a) Monsanto
82
PB 2008
Date
TUESDAY
July 1
Start
10:40 AM
End
Minisymposium
12:20 PM Minisymposium 25 – Cell to Cell and Long Distance
Signaling – Chair: Bernard Carroll
10:40 - M2501: Bernard Carroll – Genetic and Molecular
Location
Siglo XXI Convention Center Salon Valladolid
Analysis of Long-distance mRNA Silencing in Arabidopsis
11:05 - M2502: Byung-Kook Ham - Molecular characterization
of phloem-mobile ribonucleoprotein complexes
11:30 - M2503: Jeanmarie Verchot-Lubicz - Potato virus X
proteins induce ER-derived vesicles to enable plasmodesmata
transport and are targeted for degradation by the 26S
proteasome in plants
11:55 - M2504: Friedrich Kragler - A microtubule-associated
protein regulates the intercellular transport of the non-cellautonomous acting homeodomain proteins
M2501 GENETIC AND MOLECULAR ANALYSIS OF LONG-DISTANCE mRNA SILENCING IN ARABIDOPSIS
Brosnan, Chris A (a,b)
Gursanzcky, Nial (a,b)
Mitter, Neena (a,b)
Christie, M (a,b)
Lim, Sze Ying (a,b)
Smith, Neil A
(c)
Bowman, John L (d)
Waterhouse, Peter M (c)
Carroll, Bernard J-presenter [email protected](a,b)
We have been using grafting and Green Florescent Protein (GFP) to investigate the mechanism of long-distance mRNA silencing in
Arabidopsis. Rootstocks expressing a dsRNA homologous to GFP from the strong cauliflower mosaic virus 35S promoter were grafted onto
scions and induced GFP silencing in newly-formed shoots (1). Reception of silencing into shoots required components of the Pol IVa
chromatin silencing pathway, as well as RDR6, a protein known to be involved in RNA silencing. Gene silencing in scions involved both
transcriptional and post-transcriptional components (1). The molecular nature of the silencing signal transmitted from the rootstocks
remains to be elucidated. Several dicer-like (dcl) genotypes were tested for their capacity to transmit the mobile silencing signal from the
rootstock. dcl1-8 and a dcl2 dcl3 dcl4 triple mutant are compromised in miRNA and siRNA biogenesis, respectively, but were unaffected in
signal transmission (1). More recently, expressing dsRNA from a weaker promoter than 35S has been used to identify a gene affecting
transmission frequency of the silencing signal from rootstocks. These results and progress towards identifying the mobile silencing signal
will be discussed. 1. Brosnan et al. (2007) PNAS 104, 14741-14746.
(a) School of Molecular and Microbial Sciences, University of Queensland, Brisbane, 4072, Australia (b) ARC Centre of Excellence for
Integrative Legume Research, University of Queensland, Brisbane, 4072, Australia (c) CSIRO Plant Industry, Canberra, ACT 2601, Australia
(d) School of Biological Sciences, Monash University, Melbourne, 3800
M2502 Molecular characterization of phloem-mobile ribonucleoprotein complexes
Ham, Byung-Kook-presenter [email protected](a)
Brandom, Jeri (a)
Xoconostle-Cazares, Beatriz (a,b)
Lucas, William J. (a)
RNA-binding proteins (RBPs) are integral components of ribonucleoprotein (RNP) complexes and play a central role in RNA processing.
Interestingly, in plants, some RBPs have been reported to function in a non-cell autonomous manner. In this regard, the angiosperm
phloem translocation stream appears to contain a unique population of RBPs, but little is currently known regarding the nature of the
proteins and mRNA species that constitute phloem-mobile RNP complexes. In this study, we identified and characterized a 50-kDa pumpkin
(Cucurbita maxima) phloem RNA-binding protein (CmRBP50) that is evolutionarily related to animal polypyrimidine tract-binding proteins. In
situ hybridization studies revealed that CmRBP50 transcripts were present only in companion cells (CCs), whereas immunolocalization
experiments clearly detected CmRBP50 in both CCs and sieve elements (SEs). A comparison of the levels of CmRBP50 present in vascular
bundles and phloem sap indicated that this protein is highly enriched in the phloem sap. Heterografting experiments established that
CmRBP50 is indeed translocated from source to sink tissues. Collectively, these findings established that CmRBP50 functions as a non-cell
autonomous RBP. A combination of protein overlay assays, coimmunoprecipitation and cross-linking experiments were used to identify the
phloem proteins and mRNA species that comprised CmRBP50-based RNP complexes. Gel mobility-shift assays were used to demonstrate
that specificity, with respect to the bound mRNA, is established by the presence of PTB binding motifs within such transcripts. These results
will be discussed in terms of the role phloem RNP complexes play in long-distance signaling. This work was supported by grants from DOE
(DE-FG02-94ER20134) and NSF (IBN0444725).
(a) Section of Plant Biology, University of California, Davis, USA (b) Departmento de Biotecnologia y Bioingenieria, Centro de Investigacia y
Abanzados del Instituto Politenico, Zacatenco 07360, Meico
M2503 Potato virus X proteins induce ER-derived vesicles to enable plasmodesmata transport and are targeted for
degradation by the 26S proteasome in plants.
Verchot-Lubicz, Jeanmarie-presenter [email protected](a)
Ye, ChangMing (a)
Ju, HoJong (a)
http://www.ento.okstate.edu/labs/jmvl/index.html
Recent investigations using Potato virus X (PVX) to explore the role of the endomembrane network in protein transport across
plasmodesmata. PVX encodes three movement proteins required for plasmodesmata transport, named TGBp1, TGBp2, and TGBp3. We
recently completed studies showing TGBp2 and TGBp3 are in the ER and ER-derived vesicles. We also found a novel consensus element in
TGBp2 which modulates vesicle morphology. This consensus likely lies in the ER lumen and mutations in this domain alter the nature of
vesicles seen using confocal microscopy, and eliminate virus movement. These data provide the first evidence of vesicles contributing to
plasmodesmata transport Turnover of GFP:TGBp2 was enhanced in virus infected cells than in cells expressing the fusion from a CaMV 35S
promoter indicating that virus infection triggers turnover of the ER targeted protein. Deletion of the cytosolic domain of TGBp3 disrupts ER
association and virus cell-to-cell movement. MG115 and MG132 were used to demonstrate that wild-type and mutant TGBp3:GFP fusions
were degraded by the 26S proteasome. Tunicamycin, an ER-stress inducing chemical, caused lower levels of GFP and TGBp3:GFP to
accumulate in virus infected protoplasts. These observations are consistent with an ER-associated protein degradation (ERAD) pathway
suggesting that PVX TGBp3, similar to aberrant ER proteins, is translocate to the cytoplasm for degradation. Nuclear accumulation of
83
mutant and wild-type GFP:TGBp2 or TGBp3:GFP is independent of other PVX proteins and may be another feature of an ERAD pathway.
BroaderImpacts: This research represents the first characterization of a membrane bound complex involved in plasmodesmata transport.
The need to apprehend critical aspects of viral movement is a vital issue, holding profound implications for methods to understanding
disease and other biological activities. Engineering viruses to deliver targeted therapies or altering cell fate and restoring genetic defects will
require the ability to engineer the machinery controlling virus movement between cells enabling viruses to be used as vectors for targeted
delivery of inserted genes or signals.
(a) Oklahoma State University
M2504 A microtubule-associated protein regulates the intercellular transport of the non-cell-autonomous acting
homeodomain proteins
Kragler, Friedrich-presenter [email protected](a)
Winter, Nikola (a)
http://www.mfpl.ac.at/index.php?cid=52
Intercellular channel-forming organelles named plasmodesmata establish a cell-to-cell trafficking pathway for viral movement proteins and
endogenous non-cell-autonomous transcription factors; such as the two closely related meristem identity homeodomain (HD) transcription
factors Zea mays KNOTTED1 (KN1) and Arabidopsis thaliana SHOOTMERISTEMLESS (STM). KN1 and STM are DNA-binding proteins that
regulate the transcriptional activity of target genes in meristems. These transcription factors function within the nucleus, thus, a decision
between non-cell-autonomy versus nuclear import has to be made within the cytoplasm. Transfer of the non-cell-autonomous
macromolecules to neighboring cells seems to depend on specific receptors regulating access to the intercellular transport machinery. We
have identified the previously characterized TMV movement protein-interacting protein and microtubule-associated MPB2C (Kragler et al.
2004) as a HD binding protein (Winter et al. 2007). Using in vivo and in planta assays our studies establish that MPB2C controls KN1/STM
association to plasmodesmata and, consequently, KN1/STM cell-to-cell transport. In line, changes of MPB2C levels result in an A. thaliana
phenotype resembling KN1/STM miss-expression. We suggest that MPB2C links KN1/STM to microtubules and decides with the help of an
yet uncharacterized KN1/STM KNOX domain interacting protein, the availability of KN1/STM for cell-to-cell trafficking. This work is supported
by the Austrian Science Funds (FWF); Project No. P19682-Kragler.
(a) Department of Biochemistry, MFPL, University of Vienna, Austria
Date
TUESDAY
July 1
Start
10:40 AM
End
Minisymposium
12:20 PM Minisymposium 26 – Reproductive Biology – Chair:
Heather Owen
10:40 - M2601: Dazhong Zhao - Signaling of Anther Cell Fate
Location
Siglo XXI Convention Center Salon Izamal
Determination by the TPD1 Small Protein and EMS1 Receptor
Kinase in Arabidopsis
11:05 - M2602: Benjamin Rodriguez-Garay - The occurrence
and integrity of compound pollen in Agave
11:30 - M2603: Subbaiah Chalivendra - Protein-protein
interactions potentially governing pollen tube growth in tomato
(Solanum lycopersicum L.)
11:55 - M2604: Monica Alandete-Saez - Two plasma membrane
proteins expressed in the sperm cells and in the egg cell of
Arabidopsis play different roles during the fertilization process
M2601 Signaling of Anther Cell Fate Determination by the TPD1 Small Protein and EMS1 Receptor Kinase in Arabidopsis
Zhao, Dazhong-presenter [email protected](a)
Jia, Gengxiang (a)
Liu, Xiaodong (a)
Owen, Heather A. (a)
Sexual reproduction requires specification of cells with distinct fates in plants and animals. So far, little is known about the molecular
mechanisms underlying cell fate determination during sexual reproduction in plants. In flowering plants, anthers bear pollen for producing
sperm. A mature anther is usually a four-lobed structure. Each lobe contains five types of highly specialized cells, which are the epidermis,
endothecium, middle layer, tapetum and microsporocytes (pollen mother cells). Microsporocytes are reproductive cells that generate pollen
via meiosis, while somatic cells, particularly the tapetum, are required for normal development and the release of pollen. The ems1 (also
known as exs) mutant anthers lack the tapetum, but produce more microsporocytes at the expense of tapetal cells, suggesting that there is
a trade off between somatic and reproductive cells. The tpd1 mutant has a phenotype indistinguishable from that of ems1. The EMS1 gene
encodes a leucine-rich repeat receptor-like kinase (LRR-RLK), while TPD1 encodes a small, putatively-secreted protein. Here we show that
ectopic expression of TPD1 causes abnormal differentiation of somatic and reproductive cells in anthers. In addition, ectopic TPD1 activity
requires functional EMS1. Yeast two-hybrid, pull-down and co-immunoprecipitation analyses further demonstrate that TPD1 interacts with
EMS1 in vitro and in vivo. Moreover, TPD1 induces EMS1 phosphorylation in planta. Thus, our results suggest that TPD1 serves as a ligand
for the EMS1 receptor kinase to signal cell fate determination during plant sexual reproduction. A model for signaling anther cell fate
determination will also be discussed. Reference: Jia, G., Liu, X., Owen, H.A. and Zhao, D. Signaling of cell fate determination by the TPD1
small protein and EMS1 receptor kinase. PNAS (Accepted).
(a) Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA. [email protected]
M2602 The occurrence and integrity of compound pollen in Agave
Rodriguez-Garay, Benjamin-presenter [email protected](a,a)
Lopez-Diaz, Sigifredo (a)
Agaves are monocotyledoneous and monocarpic plants, and since ancient times have been important elements for the survival of humans in
continental North America. Many species have been domesticated for diverse purposes, being the production of spirits (e.g., tequila and
mezcal) and other alcoholic beverages the most important economic use since prehispanic times. On the other hand, as in the rest of
angiosperms, male gametogenesis takes place in the anthers and starts with the division of a diploid sporophytic cell, giving rise to the
tapetal initial and the very initial sporogeneus cell: the pollen mother cell, which should undergo meiosis. Normally, the product of meiosis is
a tetrad of haploid cells or microspores maintained togheter by a β-1,3-glucan (callose) wall. At maturation, these individual cells are
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PB 2008
released as free microspores by the action of the enzyme β-1,3-glucanase (callase) produced by the tapetum layer of the anther. As the
free microspores grow, they undergo one or two mitotic divisions that will give rise to four bicellular or three cellular individual units
(depending on the species) that by definition are polen grains. Here we report the occurrence of compound pollen in the form of tetrads in
Agave angustifolia (from southern Jalisco, Mexico), which has the most wide-ranging distribution of agaves in North America. The results of
this study demonstrate that the pollen grains are held together by exine bridges wich is the strongest way of pollen adhesion, and the
persistence of callose between grains acting toghether. We may speculate about the evolutive advantage that this mechanism confers to
agave species by enhancing the efficiency of pollination by enabling multiple fertilization following a single pollinator visit.
(a) CIATEJ, A.C. Unidad de Biotecnologia Vegetal
M2603 Protein-protein interactions potentially governing pollen tube growth in tomato (Solanum lycopersicum L.)
Chalivendra, Subbaiah C.-presenter [email protected](a)
Covey, Paul (a)
Martini, Dyllon (a)
Clarke, Lorelei (a)
Day,
Irene (a)
Pearce, Gregory (b)
Bedinger, Patricia (a)
Rapid Alkalinization Factors (RALFs) are recently discovered peptide growth regulators in plants. A Pollen-specific RALF (SlPRALF) from
tomato was identified in a Yeast 2-Hybrid screen using a tomato pollen LRX (a Leucine Rich repeat-eXtension chimeric domain protein) as
the bait. Based on their structure, LRX proteins are proposed to link cell expansion to external and endogenous signals (e.g., AtLRX1 in root
hair development, a tip-growing cell similar to the pollen tube; Baumberger et al., 2001). Recent work shows that a synthetic SlPRALF
peptide inhibits in vitro growth of tomato pollen tubes with no effect on pollen hydration or viability (Covey et al., submitted). Alkylation of
SlPRALF diminishes its inhibitory activity by 10-fold, indicating that disulfide interactions among cysteine residues are critical for its biological
effects. In pull-down assays, the synthetic SlPRALF interacts with the tomato pollen LRX, suggesting that the peptide may be a ligand for
the cell wall-localized LRX. Although the alkylated SlPRALF is ineffective in pull-down assays, the thiol-reagent DTT is needed for the
SlPRALF-pollen LRX interaction, indicating an intricate regulation of these two protein partners by the cell wall redox status. Y2H assays also
indicated that the N-terminus of the LRX is sufficient for its interaction with SlPRALF. In a recent additional Y2H screen with SlPRALF as the
bait, a cysteine protease with a granulin-domain was identified, which may be involved in the processing of the SlPRALF precursor. We are
analyzing the role of these protein interactions in pollen tube growth using pharmacological, reverse genetics and bioimaging approaches.
(a) Colorado State University, Fort Collins, CO 80523 (b) Institute of Biological Chemistry, Washington State University
M2604 Two plasma membrane proteins expressed in the sperm cells and in the egg cell of Arabidopsis play different roles
during the fertilization process
Alandete-Saez, Monica-presenter [email protected](a)
Ron, Mily (a)
McCormick, Sheila (a)
http://www.pgec.usda.gov/McCormick/McCormick/mclab.html
Double fertilization in flowering plants occurs when the two sperm cells, carried by the pollen tube, are released in a synergid cell of the
embryo sac and then fertilize the egg and the central cell to generate the zygote and primary endosperm cell, respectively. Proteins on the
surfaces of the sperm, egg, central and synergid cells might be important for guidance,recognition or fusion of the gametes during
fertilization. Here we present functional analyses of two plasma membrane localized proteins in Arabidopsis, GEX1 and GEX3, which are
expressed in the sperm cells and in the egg cell. Transgenic lines in which GEX3 was down regulated, using an antisense construct showed
about 50% non fertilized ovules, due to a defect in micropylar pollen tube guidance, and indicate that expression of GEX3 in the egg cell is
essential for pollen tube guidance. In lines over expressing GEX3 under the GEX2 promoter, pollen tube guidance failed and occasionally
non viable embryos were formed, suggesting that GEX3 over expression might interfere with early embryo development. Plants with a TDNA insertion in the 3 end of the GEX1 coding region had about 30% aborted seeds in which the zygote arrested at 2 or 4 cells while the
endosperm developed correctly, indicating a role for GEX1 during the first divisions of the zygote. Down regulation of GEX1 using an
antisense construct showed that GEX1 in the female gametophyte has a role in micropylar pollen tube guidance, and that in the male
gametophyte, GEX1 is required for sperm cell discharge in a synergid. Because the phenotypes of the T-DNA insertion line and the
antisense lines are different, we suggest that GEX1 has multiple roles in the fertilization process, during pollen tube guidance and
immediately after sperm and egg fusion.
(a) Plant Gene Expression Center, UC Berkeley
Date
TUESDAY
July 1
Start
10:40 AM
End
Minisymposium
12:20 PM Minisymposium 27 – Mineral Nutrition – Chair: Teresa
Hernandez Sotomayor
10:40 - M2701: Uri Pick - A unique mechanism for Fe3+ and
Location
Siglo XXI Convention Center Salon Progreso
Fe2+ acquisition in a halotolerant alga
11:05 - M2702: Jose Efrain Ramirez Benitez - Aluminium
induces changes in organic acids metabolism in Coffea arabica
suspension cells with differential Al tolerance
11:30 - M2703: Christopher M. Cohu - Reexamining the role of
superoxide dismutase in photosynthesis: plants without SOD
activity in the chloroplast and cytosol
11:55 - M2704: Georgina Hernandez – Essential role of MYB
transcription factor: PvPHR1 in phosphate starvation signaling
in common bean (Phaseolus vulgaris)
M2701 A unique mechanism for Fe3+ and Fe2+ acquisition in a halotolerant alga
Pick, Uri --presenter [email protected](a)
Paz, Yakov (a)
Weiss, Meira (a)
Katz, Adriana (a)
The halotolerant alga Dunaliella evolved a very efficient mechanism for Fe acquisition that involves binding of Fe3+ ions to the transferrin
TTf and internalization into acidic vacuoles. This mechanism enables rapid and massive binding of iron, effective discrimination of toxic
metals and a high capacity internal reservoir for iron. Under Fe deprivation, Dunaliella accumulates three additional proteins which associate
with TTf to create a high capacity Fe-binding complex. One of these proteins is a multi-copper ferroxidase,D-Fox, which functions in
85
oxidation and uptake of Fe2+ ions. We propose that Dunaliella acquired transferrins by gene transfer from primordial mammalian ancestors,
and adapted D-Fox from redox-driven to transferrin-mediated Fe uptake. This is an example of reshuffling of different proteins from diverse
organisms to create an efficient iron transport mechanism.
(a) The Weizmann Institute of Science, Deprtment of Biological Chemistry
M2702 Aluminium induces changes in organic acids metabolism in Coffea arabica suspension cells with differential Al
tolerance
Ramirez Benitez, Jose E-presenter [email protected](a)
Hernandez Sotomayor, Teresa (a)
The primary Al tolerance mechanism in plants involves exudation and/or accumulation of specific organic acid species, which form nonphytotoxic complexes with Al3+ under physiological conditions. An evaluation was done of the role of organic acids in the tolerance
mechanism of a cell suspension line of coffee (Coffea arabica L.) that exhibits Al tolerance (LAMt) but for which the metabolic tolerance
mechanism remains unknown. Significant differences existed in malate dehydrogenase and citrate synthase activities (key enzymes in
organic acids metabolism) between protein extracts (day 7 of culture cycle) of the L2 (Al-sensitive) and LAMt (Al-tolerant) cells when cell
suspensions were treated with 100 μM AlCl3. HPLC analysis showed that the suspension cells of both lines exudate malate when incubated
in a minimal solution but that exudation was not enhanced by treatment with AlCl3 (100 μM). This is the first study demonstrating that plant
Al tolerance may be associated with down-regulation of malate dehydrogenase and citrate synthase activities. This research was supported
by the Consejo Nacional de Ciencia y Tecnologia (CONACyT project No C45798-Z) and fellowships granted JERB by the CONACyT (176793)
and the Sistema Nacional de Investigadores (grant No 4422)
(a) Unidad de Bioquimica y Biologia Molecular de Plantas, Centro de Investigacion Cientifica de Yucatan
M2703 Reexamining the role of superoxide dismutase in photosynthesis: plants without SOD activity in the chloroplast and
cytosol
Cohu, Christopher M.-presenter [email protected](a)
Abdel-Ghany, Salah E. (a)
Reynolds, Kathryn A. (a)
Pilon , Marinus
(a)
The regulation and biological role of stromal superoxide dismutases has mainly been studied in the context of abiotic stress. However,
recent studies indicate that the availability of Cu is the primary regulator of cytosolic (CSD1) and stromal (CSD2) SOD activity and not stress
(Cohu and Pilon 2007; Yamasaki et al., 2007). During sufficient Cu supply, CSD1 and CSD2 are expressed and active, yet during Culimitation these Cu/ZnSODs are down-regulated while stromal FeSOD is up-regulated. During Cu-limitation, Plastocyanin levels remain high,
suggesting that the delivery of Cu to Plastocyanin is a priority. Plants contain the Cu chaperone for SOD (CCS) that delivers Cu to both CSD1
and CSD2, and in Arabidopsis is encoded by one gene that encodes both cytosolic and plastidic proteins (Abdel-Ghany et al., 2005; Chu et
al., 2005). We investigated a knock-out of CCS with no detectable Cu/ZnSOD activity. When the CCS-KO is grown with sufficient Cu these
plants also lack FeSOD activity. These CCS-KO plants without measurable stromal or cytosolic SOD activity do not exhibit a visual
phenotype, and chlorophyll fluorescence measurements do not indicate reduced photosynthetic rates compared to wild-type, even under
high light stress. Thus Cu/ZnSOD and FeSOD activities are not essential under the laboratory growth conditions imposed. The data suggest
a reconsideration of SOD function; Cu/ZnSOD could play a more important role in metal homeostasis than in oxidative stress reduction.
References cited: Abdel-Ghany et al., (2005) FEBS Letters, 579, 2307-2312; Chu et al., (2005) Plant Physiology 139: 425-436; Cohu and
Pilon (2007) Physiologia Plantarum, 129, 747-755; Yamasaki et al., (2007) Journal of Biological Chemistry 282:16369-78163.
(a) Colorado State University
M2704 ESSENTIAL ROLE OF MYB TRANSCRIPTION FACTOR: PvPHR1 IN PHOSPHATE STARVATION SIGNALING IN
COMMON BEAN (Phaseolus vulgaris)
Hernandez, Georgina-presenter [email protected](a)
Valdes-Lopez, Oswaldo (a)
Ramirez, Mario (a)
Lara, Miguel (a)
Vance,
Carroll P. (b)
Girard, Lourdes (a)
Sanchez, Federico (c)
Reyes, Jose L. (c)
Phosphorus (P), an essential element for plants, is one of the most limiting nutrients for plant growth. In Arabidopsis, several responses to P
starvation (-P) are regulated at the level of transcription, involving transcription factors (TF) such as: PHR1, WRKY75, ZAT6 and BHLH.
Despite the agronomic importance of legumes, little is known about their regulation of -P responses. Crop production of common bean
(Phaseolus vulgaris), the most important legume for human consumption, is often limited by low P in the soil. In order to study P starvation
signaling in beans, expression of MYB TF genes that were induced in -P bean roots was analyzed in detail. In particular we analyzed MYB TF
TC2883 (PvPHR1), which was induced 2-fold and showed 63% identity to the Arabidopsis PHR1 gene. In order to investigate the possible
role of PvPHR1, a RNAi approach was used to down-regulate this gene in composite bean plants. Target genes transcription analysis in -P
composite bean plants indicated that PvPHR1 TF is an essential positive regulator for P acquisition, homeostasis and transport genes but not
for phytohormone-metabolism genes involved in modification of root architecture. We identified bean genes homologous to Arabidopsis At4
(CV536419) and PHO2 (TC1095) that participate in the PHR1-mediated signal transduction pathway. In addition, a micro RNA homologous
to Arabidopsis miR399 was cloned from beans. We showed, for the first time in a legume plant, that PvmiR399 transcription by PvPHR1
increases in -P bean plants. The analysis of P-deficient DCL1-silenced composite bean plants, that showed reduced PvmiR399 levels, lead us
to conclude that PvmiR399 negatively modulates the regulation of PvPHO2 of -P target genes. A model for PHR1-mediated signaling
pathway in beans is proposed.
(a) Center for Genomic Sciences-National University of Mexico (UNAM) (b) University of Minnesota / USDA (c) Institute for BiotechnologyNational University of Mexico
86
PB 2008
Date
TUESDAY
July 1
Start
10:40 AM
End
Minisymposium
Location
12:20 PM Minisymposium 28 – Cellular Growth and Division –
Siglo XXI Convention Center Chair: William Thompson
Salon Ekbalam
10:40 - M2801: William Thompson - Analysis of DNA replication
timing on Arabidopsis chromosome 4
11:05 - M2802: Luis Vidali - Class II formins are essential for
actin organization and tip growth
11:30 - M2803: Trino Ascencio-Ibanez - Geminivirus infection
alters expression of cell cycle genes to promote endocycling in
Arabidopsis
11:55 - M2804: Carmen Quinto - Silencing a receptor-like
kinase in Phaseolus vulgaris transgenic roots arrests nodule
development by impairing vascular bundle formation
M2801 Analysis of DNA replication timing on Arabidopsis chromosome 4
Lee, Tae-Jin (a)
Pascuzzi, Pete (a)
Thompson, William F.-presenter [email protected](a)
Zheng, Ping (c)
Settlage, Sharon
(a)
Vaughn, Matthew (b)
Tanurdzic, Milos (b)
Sosinski, Bryon (a)
Main, Doreen (c)
Martienssen, Rob (b)
Hanley-Bowdoin,
Linda (a)
We have analyzed the timing of DNA replication and its relationship to other genomic features on Arabidopsis chromosome 4. We pulselabeled asynchronous cell cultures (ecotype Columbia) with BrdU, and used high-speed flow cytometry to sort nuclei by DNA content into
pools representing early S phase (G1 DNA content), middle S (intermediate DNA content) and late S (G2 DNA content). We then used BrdU
immunoprecipitation to separate pulse-labeled DNA sequences from each pool and prepared target populations for microarray analysis.
Microarray data were crosschecked by qPCR. Early replicating DNA is enriched mainly for euchromatic sequences, while late replicating DNA
is mostly enriched for heterochromatic regions, especially around the knob and centromere. Surprisingly, profiles for sequences labeled in
early and middle S phase were very similar to each other, and enrichment factors were lower than expected for a fixed order of replicon
firing. Instead of a fixed order, our results are more consistent with the hypothesis that replicons fire stochastically, at different times in
different cells, but with a tendency for those in euchromatin to fire preferentially in early and mid S phase while those in heterochromatin
tend to fire later. Additional experiments and bioinformatic analysis will explore this hypothesis and further investigate the relationship
between replication timing and other genomic features.
(a) NC State University (b) Cold Spring Harbor Laboratory (c) Washington State University
M2802 Class II formins are essential for actin organization and tip growth
Vidali, Luis-presenter [email protected](a)
Gisbergen, Peter van (a)
Augustine, Robert C (a)
Bezanilla, Magdalena (a)
Proper actin dynamics and organization are essential for polarized growth in plant tip growing cells. The tip growing cells of the moss
Physcomitrella patens contain a striking cortical F-actin fringe near the apex of the cell, which appears to be conserved throughout plant
evolution. Because formins are nucleators and enhancers of actin polymerization, essential for cell polarization in many eukaryotes, we have
analyzed their role in plant cells. Plants have two families of formins; here, we demonstate that class II formins are essential for polarized
growth, while class I formins contribute to optimal rates of growth. Moss has eight formin genes: six class I and two class II. We generated
RNAi constructs that silence all six class I, both class II, and all eight formin genes. RNAi of class I formins produces small highly polarized
plants with normal actin organization. In contrast, RNAi of class II formins leads to a dramatic loss of polarized growth; plants are dwarfed
and composed of a cluster of spherical cells. These cells have severely disorganized F-actin and no F-actin fringe. Loss of all eight formin
genes is lethal; few plants are recovered and many show signs of cell death. These data show that class II formins are essential for
establishing or maintaining polarity, demonstrating for the first time the essential role of class II formins in polarized plant cell growth. We
also show that the two class II formin genes are functionally redundant, because specific silencing of either class II formin alone has no
phenotype. Additionally, we are able to rescue the class II tip growth defect by expressing a single class II formin gene. We propose that
the critical role of class II formins in polarization is to properly assemble and maintain the subapical cortical F-actin fringe.
(a) University of Massachusetts - Amherst
M2803 Geminivirus infection alters expression of cell cycle genes to promote endocycling in Arabidopsis
Ascencio-Ibanez, Trino-presenter [email protected](a)
Sozzani, Rosangela (b)
Geiger, Krystina (a)
Lee, Tae-Jin (a)
Cella,
Rino (b)
Hanley-Bowdoin, Linda (a)
Geminiviruses are small DNA viruses that use plant replication machinery to amplify their genomes. Microarray analysis of the Arabidopsis
transcriptome in response to Cabbage leaf curl virus (CaLCuV) infection uncovered 5365 genes (FDR < 0.005) differentially expressed in
infected rosette leaves at 12 days post inoculation. Data mining revealed that CaLCuV infection impacted expression of genes involved in
the pathogen response, programmed cell death, genotoxic stress, and DNA repair. CaLCuV also altered cell cycle associated genes,
preferentially activating genes expressed during S and G2 and inhibiting genes active in G1 and M. A limited set of core cell cycle genes
associated with cell cycle re-entry, late G1, S and early G2 showed increased RNA levels, while core cell cycle genes linked to early G1 and
late G2 had reduced transcripts. Fluorescence-activated cell sorting of nuclei from infected leaves revealed a depletion of the 4C population
and an increase in 8C, 16C and 32C nuclei. Infectivity studies of transgenic Arabidopsis showed that over expression of CYCD3;1 or E2FB,
both of which promote the mitotic cycle, strongly impaired CaLCuV infection. In contrast, over expression of E2FA or E2FC, which can
facilitate the endocycle, had no apparent effect. Consistent with these results, the microarray data showed that CaLCuV infection downregulates CYCD3 expression and up-regulates E2FC expression and a subset of E2FA-target genes. Based on these observations, a model is
proposed in which CaLCuV infection actively promotes 4C cells to enter the endocycle and/or to transit from the endocycle gap phase into S
phase by selectively modulating the CYCD3/RBR/E2F network.
(a) North Carolina State University (b) University of Pavia
87
M2804 Silencing a receptor-like kinase in Phaseolus vulgaris transgenic roots arrests nodule development by impairing
vascular bundle formation.
Quinto, Carmen-presenter [email protected](a)
Jauregui, David (a)
Nava, Noreide (a)
Alvarado, Xochitl (a)
Montiel, Jesus
(a)
Rosana, Sanchez (a)
Santana, Olivia (a)
Federico, Sanchez (a)
Legumes can acquire nitrogen through a symbiotic interaction with specific rhizobacteria. Forward genetics and map-based cloning
approaches have identified important actors of the nodulation process in model legumes. Among these players, receptor-like kinases have a
key role. A receptor-like kinase with Leu-rich repeat domains (LRR-RLK) is essential for nodulation: NORK, also called MtDMI2, LjSYMRK or
SrSYMRK. Knocking down the expression of NORK by RNAi reveals to be crucial for epidermal functions and also for the release of rhizobia
from infection threads and symbiosome formation (1, 2). To gain insight into Phaseolus vulgaris receptor-like kinase (PvRLK) functions, we
determined the subcellular localization of the protein by immunolocalization during the nodulation process. The protein is located mostly in
the root central cylinder, in vascular bundles and in the nodule parenchyma. The expression pattern of PvRLK in roots and nodules was also
analyzed by RT-PCR. Transcript levels are increased in 10 and 15 dpi nodules. Transgenic P. vulgaris roots with different down-regulated
PvRLK levels suggest that this kinase plays an essential role in nodule development, in particular in vascular bundle formation. 1. Capoen et
al., 2005 PNAS 102,10369. 2.Limpens et al, 2005 PNAS 102, 10375. Partially supported by a grant from DGAPA, UNAM IN204907 (CQ).
(a) Depto. de Biologia Molecular de Plantas, Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico.
88
PB 2008
POSTER SESSIONS
Poster Location
Posters will be located in the Exhibit Hall in the Siglo XXI
Convention Center. Find your final poster number by looking up
your name in the author index in the back of the program.
Posters are numbered by category.
Poster Setup
Saturday June 28, 2008 starting at 8 am
Posters will be organized in rows by category. Put your poster
on the half side of the board below where your final poster
number is located in the corresponding session category. The
maximum size allocated for each poster is 4' x 4'. Be sure to
use a type size and font that will be easily readable. Poster pins
will be provided. Each side can hold two 4' x 4' posters. No
electrical or multi-media displays. Do not move the boards or
your poster number. If you did not submit your abstract for
poster online before the closing of the online site, place your
poster in the Late/Moved section in an open space.
Poster Display Times
All posters will be displayed daily at the Siglo XXI Convention
Center until the last event ends in the center. The hall will be
closed after the last event of the day in the center for security
reasons. Photographing, video taping, or recording of
any kind will be PROHIBITED of the posters unless a
poster author is present and provides specific
permission.
Poster Attendance during the Exclusive Poster Session
Please attend your poster during the exclusive poster session
times below according to your final poster number.
Exclusive Poster Sessions
Saturday June 28 Poster Session/Lunch 12:30-3:00 pm
12:30 PM - 1:00 PM Undergraduate Poster Session
1:00 PM - 2:00 PM Even Poster Numbers
2:00 PM - 3:00 PM Odd Poster Numbers
Sunday June 29 Poster Session/Lunch 12:30-3:00 pm
1:00 PM - 2:00 PM Odd Poster Numbers
2:00 PM - 3:00 PM Even Poster Numbers
Monday, June 30 Poster Session/Lunch 12:30-3:00 pm
All Posters
Poster Removal
All posters must be removed by 2 pm, Tuesday, July 1, 2008.
Posters not removed will be discarded.
POSTER SESSIONS
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
Session
P01 – Education and Outreach
P02 – Bioenergy Crops and Biofuels
P03 – Environmental Physiology
P04 – Integrative Plant Physiology
P05 – Maize Biology
P06 – Tomato & Solanaceous Species
P07 – Tropical Agriculture Biology
P08 – Heavy Metals & Phytoremediation
P09 – Reactive Oxygen & Nitric Oxide
P10 – Abiotic Stress
P11 – Water Relations
P12 – Membrane Transport
P13 – Mineral Nutrition
P14 – Plant-Herbivore Interactions
P15 – Plant-Pathogen Interactions
P16 – Plant-Symbiont Interactions
P17 – Cell Walls
P18 – Cytoskeleton Structure & Dynamics
P19 - Organelle Biology
P20 - Photosynthesis
P21 – Primary Metabolism
P22 – Secondary Metabolism
P23 - Lipids
P24 – Protein Targeting & Vesicular Trafficking
P25 – Intracellular Signaling
P26 – Cell-to-Cell & Long Distance Signaling
P27 – Cell Cycle & Division
P28 – Small Regulatory RNAs
P29 – Hormone Biology
P30 – Cellular Growth
P31 - Photomorphpgenesis
P32 – Vegetative Development
P33 – Root Biology
P34 – Evolution of Development & Physiology
P35 – Reproductive Development
P36 – Pollen Biology
P37 – Seed Biology
P38 - Rhythms
P39 - Tropisms
P40 – Mechanisms Of Gene Regulation
P41 – Protein Modification & Turnover
P42 - Epigenetics
P43 - Chromatin
P44 – Genome Evolution
P45 – Comparative Genomics
P46 – Quantitative Traits
P47 – Modeling & Computational Biology
P48 – Plant Systems Biology
P49 – Metabolic Engineering
P50 – Emerging Technologies
P51 – Cellular Imaging Technologies
P52 – Plant Biotechnology & Risk Assessment
Poster Numbering
Abstract numbers are preceeded with the poster session
number (i.e. P15) and then run from 001 increasing
numerically. Each category has its own set of numbers starting
from 001 preceeded with the session number. For example, the
33rd poster in the Root Biology session will be numbered
P01033. Check the author index for your final poster number.
Minisymposium speakers, place your poster under the poster
abstract number rather than their minisymposium abstract
number.
89
Session P01 – Education and Outreach
P01001 A seminar that introduces freshmen to biology research and researchers
Phillips, Dereth R. (a)
Woodward, Andrew W.-presenter [email protected](a)
Bartel, Bonnie (a)
http://www.bioc.rice.edu/bios115
Research universities have numerous scientific resources at their disposal, but they often struggle to engage potential undergraduate
biology majors. To remedy this problem, we have developed a freshman seminar to provide early exposure to biology, familiarize young
students with cutting-edge research and researchers, and encourage undergraduates to participate in research projects. The course,
Freshman Seminar in Local Biology, is taught in sections of 5-8 students to provide an intimate, personal atmosphere that is more reflective
of the social environment in which scientific research is performed than the standard large introductory science classes. Each section is led
by a graduate student or postdoctoral instructor. We have developed an extensive instructor manual and provide in-depth training for the
section leaders as they develop lesson plans and student assessments. Each section explores a different research paper published by a
featured local laboratory in our home institution, Rice University, or in the adjacent Texas Medical Center complex. Tours of the lab where
the section leader works, the lab that published the section‘s featured article, and several labs in an off-campus Texas Medical Center
department are integrated into the course. The tours allow hands-on observation as well as interaction with the researchers--professors,
graduate students, and undergraduates--who conducted the research that was studied in the classroom. In the first year of teaching the
course, evaluations from students and section leaders have been overwhelmingly positive. More details can be found on the course website:
www.bioc.rice.edu/bios115. (This work is supported by a Howard Hughes Medical Institute Professor grant to BB.)
(a) Rice University
P01002 Evaluation, Assessment, and Research in Life Science Education: What, How, and Why?
Dolan, Erin L-presenter [email protected](a)
http://www.biochem.vt.edu/faculty.php?lname=Dolan&view=yes
Whether you are broadening the impact of your research through educational activities or considering how to improve your own teaching,
evaluation will help you know when it works and help you learn when it does not. In this presentation, evaluation will be defined and
distinguished from education research and assessment. Ways to approach evaluation and assessment will be described, including the use of
qualitative and quantitative methods and consideration of findings in formative and summative ways. A variety of resources useful for
designing and implementing educational evaluation as well as mechanisms for funding your efforts and publishing your results will also be
presented.
(a) Virginia Tech
P01003 Meta!Blast: An interactive virtual reality cell to explore the complexities of biology.
Wurtele, Eve S-presenter [email protected](a)
Bacher, Denise (a)
Grover, Trent (a)
Hernnstadt, Steve (a)
Dickerson, Julie A
(a)
Brown, Trevor J (a)
Bassham, Diane (a)
http://metnetdb.org/MetNet_Meta!Blast.htm
The intricate spatial relationships and vast scale-changes in size and time that govern cellular function, from the excitation of electrons by
light to the transport of protein cargo within Golgi vesicles, provide a serious challenge to student understanding of cell biology. To address
this challenge, we have expanded on open source software to develop an open source engine designed to empower researchers and
educators in the biological community with the tools to build applications for education and research. As a proof of concept, we have used
this engine to create Meta!Blast, a 3D interactive cellular world focused on photosynthesis. The Meta!Blast cell is populated with organellar
structures based on tomographic images, and protein structures imported from Protein Data Base. It can be used in venues ranging from an
immersive high-resolution virtual environment to a laptop computer, thus it can be used in classrooms and at home. Meta!Blast captures
molecular changes using programmed laws of physics and chemistry. Unlike a movie, the student enters the cell, freely moves throughout
it, and changes scales to interact with organelles, proteins or molecules. Meta!Blast represents a synergy among biology education,
computer science, game design, and pedagogy.
(a) Iowa State University
P01004 The dynamic gene: an educational resource
Burhans, Debra T.-presenter [email protected](a)
Gutierrez, Cesar (c)
Wheeler, Robert (d)
Ware, Doreen (b)
Hilgert, Uwe
(b)
Arva, Adrian (b)
Ghiban, Cornel (b)
Micklos, David A. (b)
The goal of this project is to develop educational materials in plant bioinformatics for high school and undergraduate students and teachers.
The primary repository for these materials is the Dynamic Gene web site (dynamicgene.cshl.edu). The sites name emphasizes the dynamic
nature of the gene over evolutionary time as well as our own concept of genes that changes with our increasing knowledge of genome
organization. The context in which genes are explored is the grass family, with initial development focused on rice. The centerpiece of the
project is genome annotation, with the Evidence module devoted to types of evidence used to predict the locations of genes and other
genomic features. The Annotation module contains a number of video clips and instructions for downloading, installing, and using the Apollo
genome annotation tool, with all examples taken from the rice genome. The Projects module allows users to register, then check out
portions of the rice genome that lack annotations. Users can annotate these regions and check them back in on the website. The
annotations of others can be viewed, and annotations can be compared to those currently available on the Gramene website
(www.gramene.org). The goal of the annotation exercises is to interest students and teachers in the process of annotation and to stimulate
interest in community annotation of genomes. This process enables students and teachers to engage in real research in gene modeling.
Other modules on the website include Meaning and Structure, which together introduce concepts important for understanding molecular
biology and bioinformatics, with a focus on gene structure, and Resources. The current focus is on the development of comparative
genomics materials.
(a) Canisius College (b) Cold Spring Harbor Laboratory (c) John H. Reagan High School (d) Pine Creek High School
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P01005 Exploring stimulating ways to generate children’s interest in science: Plant Biology Workshops in Guanajuato,
Mexico
Reynaga-Pena, Cristina G.-presenter [email protected](a)
Valderrama-Chairez, Maria Leonor (b)
Garcia-Cruz, Marlen
(a)
Verver y Vargas, Aurora (a)
Cervantes, Jesus (c)
By nature, kids learn best by hands-on experiences; so, with the purpose of stimulating the interest of elementary school kids for scientific
activities, we have implemented a one-week science workshop on Plant Biology topics and related fields. A balance between every-day,
easy-to find materials and technology was addressed when designing the experiments. The expertise attained by offering this workshop
annually for 5 years in a row, and the need for this type of activities detected in our community, led us to design similar workshops for
visually-impaired children. Multi-sensorial activities were included in these workshops, with the goal of compensating the lack of vision by
stimulating other senses.
(a) Depto. de Ingenieria Genetica, Centro de Investigacion y de Estudios Avanzados del IPN Unidad Irapuato (b) Universidad de
Guadalajara (c) Centro de Investigacion en Matematicas, A.C.
P01006 Integrating Light and Electron Microscopy for Biology Teaching and Research
Hou, Guichuan-presenter [email protected](a)
Henson, Dru A (a)
The microscope is a virtually indispensable tool for biology teaching and research. A dissecting microscope is suitable for observing whole
objects but with limited magnification. A compound microscope can achieve considerably higher magnification and a variety of microscopy
methods such as differential interference contrast (DIC) and fluorescence staining but with limited sample thickness. Electron microscopes
can resolve features that are much smaller than those resolvable with light microscopes but usually requiring complicated procedures for
sample preparation. Each type of the microscope has its own qualities, capabilities, and limitations. Laboratory (dissecting and compound)
microscopes are currently used in both Botany and Zoology lab practices in the Department of Biology at Appalachian State University
(ASU). Microscopy theory, however, is not a part in those curricula and therefore, most students in the classes do not really understand how
a microscope works. This hinders the efficiency of how the microscope should be used and cared by students in the labs. Meanwhile, most
procedures of biological microscopy involve sample preparations that vary in accordance with specimen and choice of microscope. The
microscopy sample preparations are not included in the curricula mentioned above either. The Dewel Microscopy Facility in the College of
Arts and Sciences at ASU currently offers Independent Study of Microscopy for undergraduate and graduate students, which is designed to
meet individual needs on both theory and sample preparation for laser scanning confocal microscopy, scanning electron microscopy, and/or
transmission electron microscopy. An introductory microscopy course that emphasizes principles of light and electron microscopy is under
construction.
(a) Appalachian State University
P01007 An inquiry-based plant genomics course and workshop: Phenotype to gene and back again
Colon-Carmona, Adan -presenter [email protected](a)
Springer, Patricia (b,b)
Engaging high school and undergraduate students in research projects during course work is both difficult and time-consuming. Moreover,
how does one integrate plants, particularly Arabidopsis, to increase interest and excitement in studying genomics? We have developed a
two-step year-long approach to incorporate Arabidopsis 2010 research projects into Boston area biology high school classrooms. This
includes a recruitment strategy at area biotechnology and education symposia, an intensive one-week summer workshop for high school
teachers, and an academic year follow-up program. In a plant biology undergraduate course, the laboratory portion is used to facilitate a
semester-long research experience using genetic resources available from the Arabidopsis community and which are being generated as
part of an Arabidopsis 2010 project. Undergraduates conduct self-directed projects to investigate their own hypotheses on a specific
member of the gene family being studied. At the end of the course, projects are presented in a symposium format. A summary of the
activities and these experiences with students and teachers will be presented.
(a) Univ. of Massachusetts Boston (b) Univ. of California Riverside
P01008 Plant peroxidases: a semester long research project in a molecular biology class
Kleinschmidt, Ann M-presenter [email protected](a)
Fekete, Megan L (a)
Dudzinski, John E (a)
http://webpub.allegheny.edu/employee/a/akleinsc
A semester long research project has been developed that exposes undergraduate students in the laboratory component of a Molecular
Biology class to bioinformatics, cDNA cloning, sequence analysis, and real-time PCR. Each group of students in the class is provided an
accession number for a class III peroxidase from Arabidopsis thaliana and use this to locate the cDNA sequence in the TAIR database. This
cDNA sequence is used to perform a BLAST search against a Brassica rapa EST database. From the EST sequence they design a primer for
cDNA synthesis. Using 3‘-RACE. students then synthesize cDNA using this primer, clone the cDNA, and submit the cDNA for sequencing.
Students use the resulting sequence to do further BLAST homology searches, both at the nucleic acid and protein levels, and use Biology
Workbench to obtain sequence alignments. In addition to the work in bioinformatics, students use the sequence to design primers for
analysis of mRNA levels in different tissues of Brassica rapa FastPlants using real-time PCR. Students use the data gathered during the
semester long project to write a primary literature style paper. Undergraduate students have been integral members in the development of
the semester long project, trouble shooting and fine tuning protocols to be used in the course, as well as development of in class exercises
to facilitate understanding of the techniques used as well as to help in understanding how the different techniques connect to allow
completion of this project.
(a) Allegheny College, Biology Department and Biochemistry Program
P01009 Lost crops of Africa: Involving undergraduates in their rediscovery and development
Cullis, Christopher A.-presenter [email protected](a)
Lost crops of Africa: Involving undergraduates in their rediscovery and development Christopher A. Cullis Department of Biology, Case
Western Reserve University, Cleveland, OH 44120 e-mail: [email protected] A laboratory course has been designed to engage undergraduate
students in developing useful DNA markers for under-utilized crops in Africa while also getting an international experience. This course
specifically tries to avoid a common preconception of laboratory courses, namely, if the experiment works then there is not much
satisfaction since the experiments are set up to ensure that they work and there is a definitive answer to the questions posed. The focus of
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the course for the past 3 years has been on developing useful DNA markers, with each class building on previous years results. The crops
initially targeted were bambara nut, banana, cassava, cowpea and marama, but marama bean (Tylosema esculentum) has now been
selected as the focus crop for the next few years. These student efforts should result in a high density SSR molecular map of marama. The
international component involves web video links for live interactions between students and faculty in Cleveland, Pretoria and Windhoek,
where the data will be put to direct use in a proposed breeding project. Dr. Percy Chimwamarumbe from Namibia was an active participant
in the course for two weeks in Fall 2007. Up to 36 students are enrolled each semester (the course is being offered twice a year) and it has
been positively and enthusiastically evaluated by the students. The development of this course was supported by a World-Wide Learning
Experience grant, a McGregor Fund initiative in the College of Arts and Sciences, Case Western Reserve University (to CAC) and a grant
from the Kirkhouse Trust (to PC).
(a) Case Western Reserve Universitiy
P01010 Video podCasts as a teaching tool in Plant Physiology laboratory courses
Schulz, Burkhard-presenter [email protected](a)
Nucera, Diana J (a)
Holladay, Steven (a)
Van Oosten, Michael (a)
http://www.hort.purdue.edu/hort/people/faculty/schulz.shtml
We have developed a set of educational tools in form of video archives to enhance the student ability to learn and appreciate plant biology.
We present the production, student use, and assessment of student-produced video podcasts used to augment plant physiology labs at
Purdue University. Our project addresses the diverse student composition participating in plant physiology (HORT301) at Purdue University.
One of the problems we are able to address is the knowledge gap of students with less experience in experimentation while still challenging
students who are already familiar with the methodology. Our goals are to enable the students to 1) identify basic terminology related to lab
and research procedures, 2) to identify single basic steps in lab and research procedures, 3) to carry out basic steps in lab and research
procedures and to 4) develop a positive attitude towards the process of scientific discovery. We will discuss the process and obstacles
involved in setting up laboratory podcasts as well as an evaluation of the feedback we have collected from undergraduate students that
have particpated in the enhanced learning experience.
(a) Purdue University, Department of Horticulture, West Lafayette, IN 47907, USA
P01011 Web-based biology teaching resources
Moreno, Nancy P-presenter [email protected](a)
Erdmann, Deanne B (a)
Tharp, Barbara Z (a)
GrandPre, Tadzia (a)
http://www.bioedonline.org
BioEd Online (www.bioedonline.org), Baylor College of Medicine‘s award-winning website, offers up-to-date biology content, news, and
professional development resources appropriate for educators of all levels, including undergraduate instructors. Learn how to access peerreviewed, annotated PowerPoint slides; entertaining videos to focus students‘ attention; streaming video content and ―how-to‖ laboratory
presentations; inquiry-based lessons; and science education outreach resources, including teacher short courses. An asynchronous,
problem-based undergraduate course on genetics and genomics will be launched in fall 2008.
(a) Baylor College of Medicine
P01012 Expanding Plant Genomics Training and Research Opportunities for Undergraduates
Dhir, Seema -presenter [email protected](a)
Singh, Hari P (a)
Dhir, Sarwan K (a)
http://www.fvsu.edu
Plant genome outreach programs increasingly play an important role in providing opportunities for the community at large to participate
effusively in the latest developments under plant genomics. To increase the number of undergraduate student participation in the plant
genomics, we have initiated an undergraduate degree program in Plant Sciences with a Biotechnology major. Students are exposed to basic
principles and application of biotechnology through hands-on experience in basic genetic engineering and molecular biology techniques.
Student recruitment and retention is supported by financial support in the form of NSF and USDA Plant Science-Biotechnology scholarship
(52 scholars). In addition, we have developed collaborations with major institutions for students to conduct summer internship in
biotechnology for 8-10 weeks. Students improve scientific aptitudes, skills and become proficient in the use of scientific techniques. In the
past six years, more than 150 students have participated in such programs. Besides acquiring the academic and laboratory skills, students
interact with invited speakers which improve their written/oral communication and leadership skills and help prepare them for award
winning presentations at scientific meetings . The program has been well received by students, and several of them have already joined
MS/PhD program in Plant Molecular Biology and others are in pipeline to attend graduate school. Hypothetically, students matriculating from
our program will have a strong foundation in agricultural biotechnology. Their skills will be enhanced by research training received during
summer internships, and links will be established for further study at the graduate level to increase the number of minority students
entering into STEM fields.
(a) Fort Valley State University
P01013 PlantingScience.org: On-line science inquiry by students and teachers mentored by scientists.
Griffing, Lawrence-presenter [email protected](a)
Hemingway, Claire (b)
PlantingScience.org is an on-line system developed to guide teachers and students through open-ended experimentation on plants. The online system brings together students, teachers, and scientist mentors for a period of approximately two weeks, during which time students
ask and test their own questions about plants. In Fall 2007 and Spring 2008, 141 scientist mentors coached 1,233 students, working in 368
teams, through the process of scientific discovery. The current inquiry units in the program, The Wonder of Seeds, The Power of Sunlight,
and The Genetic Basis of Variability (beta testing), are designed to adapt to different classroom environments and timeframes. An example
student project is presented. Teachers have been trained at Botanical Society of America (BSA) workshops, and, now, under a new NSFfunded program, by professional development summer workshops at Texas A&M University for teachers. Mentors are trained at short
workshops at annual meetings of the BSA and the ASPB. There are 17 graduate student mentors, Master Plant Scientists, sponsored by the
BSA and the ASPB. Assessment of the program to date has included surveys of mentors, teachers and students. The results of the mentor
survey indicate that some mentors change their teaching to include more inquiry or more peer mentoring in the classroom. The program is
actively recruiting mentors, who, by participating, engage in meaningful educational outreach and share their excitement about plants, their
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insights, and their knowledge of the process of science, with the next generation of scientists.
(a) Texas A&M University (b) Botanical Society of America
Session P02 – Bioenergy Crops and Biofuels
P02002 Does increased carbon assimilation coupled with a higher Leaf Area Index explain the difference in productivity
between two potential bioenergy crops?
Dohleman, Frank G.-presenter [email protected](a)
Long, Stephen P. (a,b)
http://www.miscanthus.uiuc.edu
An economically and energetically favorable bioenergy crop must be able to produce large quantities of biomass with minimal inputs. The
C4 crops, switchgrass (Panicum virgatum), Miscanthus (Miscanthus x giganteus) and maize (Zea mays) have been touted as potential
energy crops. Until now their productivity has not been directly compared. In side-by-side trials in central Illinois, USA, Miscanthus was
nearly three times as productive as switchgrass, and twice as productive as maize. Understanding why Miscanthus is more productive will
indicate how other potential bioenergy crops might be engineered to increase productivity. We have shown previously from field trials in
2005 and 2006 that leaf level carbon assimilation, leaf area index (LAI), and length of growing season are all significantly higher in
Miscanthus than in switchgrass. In 2007, the diurnal course of gas exchange was measured in situ on upper canopy leaves of each species
on 13 dates throughout the growing season. Assimilation rate of maize was up to 60% higher than Miscanthus (p<0.0001). LAI, was
measured destructively on the same dates, and was on average more than double for Miscanthus when compared to maize (p<0.0001).
Finally the growing season length for Miscanthus was 64 days longer than it was for maize. In summary, the growing season length and LAI
were higher for Miscanthus, but leaf level carbon assimilation was higher for maize.
(a) Department of Plant Biology University Of Illinois (b) Department of Crop Sciences University of Illinois
P02003 Mass propagation and improvement of Arundo donax a promising biomass energy crop
Marton, Laszlo-presenter [email protected](a)
Czako, Mihaly (a)
Pollock, Robert (b,b)
Monoculture forming monocots are important components of different ecosystems and are often able to produce huge biomass, more than
most cultivated plants. Tissue culture is prerequisite for both large scale propagation for environmental biotechnology applications and
genetic manipulations, such as mutant selection and genetic improvement by introduction of key transgenes which can significantly improve
their utilization for remediation and increase their biomass quantity and quality. We have developed a universal cell culture initiation
medium and procedure which allowed us to establish embryogenic cell cultures, micropropagation and genetic engineering protocols, which
have successfully been used for a great number of species from a diverse group of monocot species (Cyperaceae, Juncaceae, Poaceae, and
Typhaceae). Our technology has been fully explored with Arundo donax, (20-50 DTY/acres biomass) down to the large scale application
details, including storage, transportatation and deployment. An improvised lab with a max 200,000 sqft nursery unit can produce
60,000.000 propagules (for 6.000 ha land) with 1 laboratory personal/500,000/Y propagules and 1 nursery worker/100,000/Y proagules The
method comprised using immature inflorescences as explants and cultivating the tissue on a primary medium to produce totipotent
embryogenic tissue culture, cultivating the embryogenic tissue on a secondary medium to produce regenerating cultures, then sustaining
shoot multiplication and production of complete plantlets having roots and shoots on tertiary medium before acclimating the plantlets in soil.
The sustained totipotent embryogenic cultures allowed efficient somaclonal berreding, elit lines for TCP dehaloperoxidation and for salt
tolerance have been selected.
(a) University of South Carolina (b) Southern Sun Biosystems Inc
P02004 Expression of a cyanobacterium plasmamembrane Na+/H+ antiporter in rice reduced sodium accumulation and
enhanced its salt tolerance
Ku, Maurice S.B.-presenter [email protected](a)
Chent, S.Y. (a)
Wang, C.L. (a)
Park, I. (b)
Yen, Y.F. (a)
Under saline conditions, cyanobacteria use plasmamembrane Na+/H+ antiporter to transport Na+ out of cell. This adaptive mechanism
allows cyanobacteria to reduce the accumulation of Na+ and its harmful effects in the cell, allowing normal metabolic activities in the
cytoplasm to proceed. In this study, a cyanobacterial Na+/H+ antiporter gene (nhaS4) was introduced into rice via Agrobacterium-mediated
transformation. Molecular analyses showed the cyanobacterial gene is integrated into the genome of transgenic rice and expressed
constitutively in various tissues. Physiological analyses exhibited no significant differences between transgenic and non-transgenic rice in the
contents of various ions when grown under normal (low salt) conditions. However, when grown under saline (100 mM NaCl) conditions,
transgenic rice accumulated 24% and 70% less (P<0.01) Na+ in the root and leaf, respectively, as compared to non-transgenic rice. In
contrast, no differences in Cl- content were found between the two genotypes under normal or salt conditions. These results demonstrated
the specificity of this transporter against Na+ and its effectiveness in reducing the accumulation of Na+ in the cell. Most importantly, the
degrees of inhibition by NaCl on growth of seedlings and leaf photosynthesis were 12-15% lower (P<0.05,P<0.01) in transgenic than in
non-transgenic rice. Taken together, this study clearly demonstrates that the cyanobacterium Na+/H+ antiporter gene ( nhaS4) can be
properly expressed in rice and effectively prevent Na+ accumulation in the cell for enhanced salt tolerance. A similar approach can also be
applied to other crops for the improvement of yield and quality in saline environments.
(a) Institute of Agricultural Biotechnology, National Chiayi University, Chiayi, Taiwan (b) Department of Biochemistry, Chungnam University,
Chungnam, South Korea
P02005 Sucrose Hyperaccumulation Associated with Ionome Changes during Development
Weil, Clifford F.-presenter [email protected](a,b)
Salt, David (c)
Braun, David (d)
Maize varieties that accumulate large amounts of sucrose in their vegetative tissues instead of producing large ears can be an outstanding
alternative feedstock for biofuel production. Tropical varieties grown in temperate U.S. conditions often flower very late or make no ears at
all and, instead, accumulate levels of sugar in their vegetative tissues that exceed those of sweet sorghum and can rival sugarcane. In
contrast, temperate-adapted varieties like B73, if the ear is removed as a carbon sink, also show hyperaccumulation of sucrose, but also
show premature senescence. To better understand the basis of this difference, we have used the tie-dyed1 (tdy1) mutant of B73, which
produces nonclonal sectors of yellow leaf tissue associated with hyperaccumulation of sucrose. In addition these sectors senesce earlier
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than green tissue n the same leaf, providing a useful test system for responses to increased sugar levels. We have examined mineral levels
and patterns of accumulation over development in hyperaccumulating as compared with nonaccumulating and nonmutant leaf tissue using
Inductive Plasma-Coupled Mass Spectrometry (IPC-MS). Sucrose accumulation is associated with specific changes in the ability to
accumulate Ca, Cu, Mg, S, Mo, Fe and Mn, particularly in older leaves. Sucrose-nonaccumulating sectors of tdy1 leaves show increased
levels of K and P compared to sucrose-accumulating and nonmutant tissue.
(a) Dept. of Agronomy, Purdue University (b) Whistler Center for Carbohydrate Research, Purdue University (c) Dept. of Horticulture and
Landscape Architecture, Purdue University (d) Dept of Biology, Pennsylvania State University
P02006 Production of Microbial Cellulase in Transgenic Plants for Biomass Conversion
Gray, Benjamin N-presenter [email protected](a)
Ahner, Beth A (a)
Hanson, Maureen R (b)
Enzymatic cellulose hydrolysis is the preferred method for converting cellulose to ethanol. The cost of microbial cellulase production
currently represents a major barrier toward the realization of economically competitive cellulosic ethanol. Transgenic plants represent an
attractive platform for low-cost protein production due to low scale-up costs relative to microbial protein production and thus could help to
clear the barrier of cellulase production cost. By transforming the chloroplast genome rather than the nuclear genome for foreign protein
expression, high yields of certain foreign proteins have been realized, but other proteins accumulate only to low levels. Our goal has been to
learn how to design chloroplast transgenes to achieve high-level expression of microbial cellulases. Tobacco is our test system because of
the relative ease in transforming its chloroplast genome. Constructs carrying the Thermobifida fusca cel6A gene under the control of
different gene regulatory elements were bombarded into tobacco leaves and transplastomic tobacco plants were regenerated. Cel6A protein
accumulation varied over 30-fold in young leaves of transplastomic tobacco transformed with the three different cel6A transgenes tested.
Differences in protein accumulation in aging leaves were also observed among the three cel6A genes. In the best case, Cel6A protein
accumulated to 3.5% of total soluble protein (%TSP) in young leaves and up to 7.6%TSP in mature leaves. Chloroplast-produced Cel6A was
purified from a crude protein extract by cellulose affinity chromatography and was found to be active against carboxymethylcellulose (CMC).
Experiments are underway to further optimize the production of microbial cellulases in plants.
(a) Department of Biological and Environmental Engineering, Cornell University (b) Department of Molecular Biology and Genetics, Cornell
University
P02007 Genomic, Transcriptomic, Proteomic and Functional Analysis of Candidate Genes for Bioenergy Feedstock
Improvement
Yuan, Joshua S.-presenter [email protected](a)
Stewart, Nathan R. (a)
Kline, Lindsey (b)
Dai, Susie Y (c)
Hettich, Robert L
(c)
Hayes, Douglas G (b)
Stewart, Neal (d)
Here we present the discovery and characterization of candidate genes for bioenergy feedstock improvement in rice and switchgrass from
four perspectives. First, comparative genome analysis of ten monolignol biosynthesis gene families in rice, Arabidopsis and poplar revealed a
surprising lack of coordinative evolution of monolignol biosynthesis genes and helped to identify important conserved genes for lignin
modification. Second, cell wall-related genes are studied with transcriptomic and proteomic approaches. Microarray gene profiling among
different tissues revealed a coordinative up-regulation of cell wall biosynthesis and expansion genes such as CES, glycosyltransferase,
expansins, XTHs in the cotyledon, whilst fewer cell wall genes were found up-regulated in the adult stem. Surprisingly, although the adult
stems contain more lignin, much more lignin biosynthesis genes were up-regulated in the cotyledon. The transcriptomics thus needs to be
complemented by the proteomics, where cell wall proteins from the same tissues are being extracted and compared with 2D-DIGE and online shotgun LC-MS/MS approaches. Third, according to the omics analysis, mutants with down-regulated lignin biosynthesis were analyzed
for saccharification efficiency. While most of the rice lignin mutants displayed higher saccharification efficiency, the F5H mutant showed a
significant 50% decrease, which indicated the importance of both lignin composition and content for saccharification efficiency in monocot
species. Fourth, based on the rice studies, we have cloned and analyzed important lignin biosynthesis genes in switchgrass, and RNAi
mutants are being generated. Overall, the omics approaches can be highly effective in identifying key genes for monocot bioenergy
feedstock improvement.
(a) UTIA Genomics Hub, University of Tennessee, Knoxville (b) Biosystems Engineering, University of Tennessee, Knoxville (c) Organic and
Biological Mass Spectrometry Group, Oak Ridge National Laboratory (d) Department of Plant Sciences, University of Tennessee, Knoxville
P02008 State and conditions of biofuel using and production in Poland
Borodynko, Natasza-presenter [email protected](a)
Wisniewski, Waclaw (b)
As a European Union country Poland has the biggest agrarian reserves which means it could be self-sufficient in the process of achieving
the expected production of fuel biocomponents. There is 0.34 ha of arable land per 1 citizen in Poland (in the EU it is 0.18 ha). The area of
fallow is more than 2 million ha. It creates good conditions for alternative production. The sugar market reform, as well as the decrease of
sugar beet growth area, create a reserve of about 2 million tonnes of sugar beet which could be used for energy purposes. There are going
to be some changes in the structure of maize growing for corn by about 200 thousand ha. There is also a possibility to increase the crops of
corn to 5.5 tonnes form 1 ha. The structure of agrarian products usage for ethanol production is going to be changed. Presently, 80% of
ethanol is being produced from corn, 10 % from beetroot black treacle, and 4-6 % from potatoes. The demand for bioethanol is going to
increase from 140 million m3 in 2007 to 430 million m3 in 2013. The rate of of biocomponents and other renewable fuels usage in the
general amount of liquid fuels is going to increase from 3.45% in 2008 to 5.75% in 2010, and 7.10% in 2013. The installations for biodiesel
production which are supposed to be finished till May 2007 should provide production capacity of 1150 tonnes. Installations for sugar beet
bioethanol production are not being prepared, and overproduction of sugar beet juice over the EU sugar limitations is going to be used for
ethanol production. The installations can be created basing on sugar factories which are not needed any more. The expenses for bioethanol
production in 2007 were about 150 million euros. In 2008 this amount is going to increase up to 300 million euros.
(a) Institute of Plant Protection (b) KWS Polska
P02009 Expression assays of lignin biosynthesis genes in switchgrass stems
Nuxoll, Austin S-presenter [email protected](a)
Barber, Anna (a)
Twigg, Paul (a)
Switchgrass is characterized as a warm-season perennial grass. It is able to tolerate diverse environments having a range that extends from
Quebec to Central America. With every passing day, the U.S. has a growing dependence on foreign oil and because of this dependence we
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are turning to alternative fuels. Among these are biofuels, while bioenergy crops won‘t replace oil they could greatly reduce our
dependency. Switchgrass has the potential to have a great impact on bioenergy. It however has significant challenges. One of these is the
presence of lignin in its cell walls. Lignin presents a problem because it can not be broken down into a form useable for bioenergy through
current processes at an efficient cost. My project was designed to examine the level of lignin biosynthetic gene expression in switchgrass
stems, varying in ages and strains, by semi-quantitative PCR. The levels of caffeic acid-o-methyltransferase (OMT), cinnamyl alcohol
dehydrogenase (CAP), and cinnamoyl CoA reductase (CCR) are all important for the lignin pathway to continue, and will inform us about
how much lignin is being synthesized. RNA has been extracted from all of the samples and assays of gene expression are currently being
performed. We will present and analyze our findings to date. This project was supported by NIH grant P20 RR016469 from the BRIN
program of the National Center for Research Resources and the University of Nebraska-Kearney Department of Biology.
(a) University Of Nebraska-Kearney
P02010 Differences in herbicide resistance of sugarcane (Saccharum spp.) cultivars correlated with Glutathione stransferase basal gene expression
Figueira, Antonio-presenter [email protected](a)
Nishimura, Deborah S (a)
Ferreira, Renato R (a)
Christoffoleti, Pedro J (b)
Glutathione S-transferase (GST) is a multifunctional enzyme that has been associated with non-target site herbicide resistance in various
crops. Sugarcane cultivars appear to differ for herbicide resistance, which could derive from differences in GST gene expression. A complete
search of the Saccharum Gene Index database was conducted for GSTs from the classes Phi, Tau, Theta and Zeta using the 61 rice GST
genes, and the conceptually translated sequences were used in a phylogenetic analysis. Eighteen EST clusters (from 355 ESTs or 0.14% of
the database) were identified and classified into 7 groups as belonging to the Phi class (denominated ScGSTF); 7 as Tau (ScGSTU); one as
Theta (ScGSTT); and 3 as Zeta (ScGSTZ). The 18 clusters of sugarcane ESTs were equivalent to the mostly expressed orthologues in rice.
Total RNA from various organs/tissues, and from leaves from cultivars SP80-3280 (resistant to herbicides) and SP87-365 (susceptible),
collected before or 48 h after treatment with herbicides (Ametryn; Diuron; Imazapic; Isoxaflutole) were obtained and analyzed by RT-qPCR.
In general, genes from Phi and Tau classes were the most expressed, with ScGSTF3, ScGSTU8 and ScGSTU13 were more expressed in
leaves. Constitutive expressions of ScGSTF3, ScGSTF4, ScGSTU8, ScGSTU13, and ScGSTU17 in leaves were significantly superior in cultivar
SP80-3280 than SP87-365. In response to herbicide treatments, GSTs expression was induced in response to Ametryn or Diuron, but not to
Imazapic or Isoxaflutole. ScGSTF3, ScGSTF4, ScGSTU13 and ScGSTU17 displayed significant differences in expression between cultivars 48
h after herbicide treatment. These genes might be associated with differences between cultivars for herbicide detoxification, and possibly
linked to resistance.
(a) Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo (b) Escola Superior de Agricultura "Luiz de Queiroz", Universidade
de Sao Paulo
P02011 A novel approach toward lignin modification to facilitate cellulosic ethanol production: introducing a tyrosine-rich
cell wall peptide gene in poplar
Liang, Haiying-presenter [email protected](a)
Frost, Christopher J. J (b,c)
Brown, Nicole R (c)
Carlson, John E (b,c)
Tien,
Ming (d)
Lignin degradation is of critical importance in biomass utilization of woody plants, since the presence of lignin limits hydrolytic enzyme
access to cellulose and hemicellulose. To date, strategies for lignin removal have ranged from treatment with lignin-degrading fungi to
genetic manipulations that reduce lignin content or monolignol composition. However, reducing lignin content without compromising tree
fitness can be difficult. Here we report an alternate approach to lignin modification. We have attempted to modify lignin composition by
introducing in situ peptide crosslinks; we hypothesize this will not change overall lignin content or distribution in the cell wall, yet should
render the lignin more susceptible to protease digestion. To test this, we over-expressed a transgene encoding a high tyrosine-content
peptide in lignifying tissues of hybrid poplar. Relative to wildtypes, the transgenics had no change in total lignin content or morphology,
though a number of lines had less tensile strength. As predicted, a number of transgenic lines were more susceptible to protease digestion
than wildtypes, resulting in a higher polysaccharide release from the lignocellulose complexes. Although preliminary, our results suggest this
may be a viable means to facilitate lignin removal and potentially advance the utilization of woody biomass as a biofuel feedstock.
(a) Department of Genetics and Biochemistry, Clemson University (b) Center for Chemical Ecology, The Pennsylvania State University (c)
School of Forest Resources, The Pennsylvania State University (d) Department of Biochemistry and Molecular Biology, The Pennsylvania
State University
P02012 Functional Characterisation of Genes Regulating Cell Wall Structure and Composition
Kjaer, Lars-presenter [email protected](a)
Hamann, Thorsten (a)
Wormit, Alexandra (a)
Denness, Lucinda C J (a)
Madhou,
Priyadharshini (a)
Carraca, Luis (a)
We are performing an analysis of the mechanisms regulating cell wall structure and composition in response to cell wall stress (CWS). In
order to identify genes involved in the CWS response a time course microarray experiment was carried out using isoxaben (a herbicide that
causes cellulose biosynthesis inhibition (CBI)) treatment to induce CWS and a phenotypic analysis was performed. Approximately 2500
genes exhibited significant transcriptional changes in response to the treatment. A list of 100 genes was created by cross-referencing with
genes highly expressed in the root elongation zone and the stem thus suggesting they may be involved in cell wall remodelling or formation.
Currently knockout mutants for the candidate genes are being isolated and their cell wall composition and structure characterized using
chemical analysis, diagnostic enzymes and FTIR clustering analysis. We will present the results from the functional characterisation of some
of the candidate genes.
(a) Imperial College
P02013 The plant cell wall integrity maintenance system
Carraca, Luis-presenter [email protected](a)
Hamann, Thorsten (a)
Deness, Lucinda (a)
Madhou, Priyadharshini (a)
Wormit ,
Alexandra (a)
Kjar, Lars (a)
Plant cell walls form the bulk of plant derived biomass used for production of carbon neutral biofuels. Their composition/structure influences
the efficiency with which biofuels can be produced. The responsive nature of the cell wall to external stimuli suggests the existence of a
complex system for sensing, signalling and feedback responsible for adaptations (Humphrey et al, 2007). Understanding this mechanism will
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allow us to optimise cell wall composition/structure and increase efficiency of biofuels production. Cellulose biosynthesis inhibition (CBI) is a
highly specific tool to create cell wall stress (CWS), allowing to characterise changes in cell wall composition/structure. 4h of CBI cause
activation of lignin biosynthetic, pathogen signalling and mechano-stress responsive genes (Hamann et al, 2004). After 5h of CBI, lignin
deposition is detectable in the primary root of A. thaliana. Providing osmotic support suppresses this lignin deposition suggesting that CWS
perception may occur through mechano-perception. Also, CBI downregulates photosynthetic genes. The sink-source relationships between
cellulose biosynthesis, primary metabolism and photosynthesis are also an area of research. Global expression profiling has identified 10
genes that are transiently activated during the first 12h of CBI suggesting a specific role in early signal translation or CWS response. A
functional characterisation of these genes is currently under way and we are determining whether homologues exist in bioenergy crops like
miscanthus, poplar or willow. If so, their biological function in the bioenergy crops will be determined by altering their gene expression
levels and their phenotype characterised, being the ultimate goal the optimisation of biofuel production from these crops.
(a) Imperial College London
P02014 Expression analysis of Medicago stem internodes identifies genes associated with regulatory control and
biogenesis of plant cell walls
Tesfaye, Mesfin-presenter [email protected](a)
Jung, Hans (b)
Samac, Deborah (b)
Gronwald, John (b)
Lamb, JoAnn
(b)
Vance, Carroll (b)
VandenBosch, Kathryn (a)
Legumes have many traits that make them attractive bioenergy crops, especially as components of mixed grass stands or in crop rotations
with maize. Alfalfa is a legume with an advantage as a biomass crop because of its easy separation of leafs for livestock feed and stems for
conversion to syngas and/or fermentation to ethanol. Nevertheless studying alfalfa is challenging because it is a cross-pollinated and
autotetraploid plant. Evaluation of the closely related diploid Medicago truncatula, with well-developed genetic and genomic resources,
would facilitate analysis of biomass traits. We expect that understanding of systems controlling primary and secondary cell wall composition
in Medicago will facilitate improvement of biomass production or quality in alfalfa and related dicots. Stems of alfalfa and M. truncatula
undergo two distinct developmental phases: primary growth in elongating stem internodes, involving increase in cell size and deposition of
primarily non-lignified primary cell walls, and cambial activity in post-elongation internodes, resulting in deposition of secondary xylem. We
have utilized the Affymetrix Medicago genome array to profile expression patterns in stems of two M. truncatula ecotypes and two alfalfa
clones with contrasting cell wall composition. Transcripts were detected from 33% to 47% of probe sets, depending on genotype. Most of
the detected genes were expressed in both elongating and post-elongation stems, although at different expression levels. Numerous genes
with differential expression patterns have predicted roles in cell wall biosynthesis, structure and modification; transcriptional regulation; and
signaling. Our poster will explore patterns of cell wall-related gene expression in Medicago stems among different genotypes.
(a) University of Minnesota (b) Usda_Ars
P02015 eQTL Analysis of Soybean Seed Composition and Yield Traits
Lin, Rongshuang (a)
Gibson, Susan I-presenter [email protected](a)
Glazebrook, Jane (a)
Katagiri, Fumiaki (a)
Orf, James
(b)
http://www.cbs.umn.edu/plantbio/faculty/GibsonSue/
Although soybean shows great promise as a source of biodiesel, improvements in seed composition and/or yield are needed to make
production of biodiesel from soybean economically competitive. To develop new varieties with the best possible seed composition and yield
characteristics, it is necessary to have more information regarding the genes that control these traits. Regulation of gene expression likely
plays a critical role in determination of desirable traits. In brief, a major part of the reason that two varieties differ in these traits is that the
varieties differ in the expression levels of important genes. So, by identifying the genetic factors that control variations in gene expression, it
should be possible to identify many of the genetic factors that control variations in seed composition and yield. The first step in identifying
these genetic factors is to identify genes that are expressed at different levels in the two varieties of interest. Towards this end Affymetrix
Soybean GeneChips have been used to identify such variably expressed genes from developing seeds of two recombinant inbred lines (RILs)
developed from the Minsoy and Archer varieties. In future experiments the expression levels of these variably expressed genes will be
measured in many additional RILs. These measurements will allow determination of how high and low expression of these genes segregates
in the different RILs. By comparing the segregation of high and low gene expression with the known segregation patterns of molecular
markers, it will be possible to identify expression quantitative trait loci (eQTL) that are responsible for regulating the variations in gene
expression and, by extension, variations in seed composition and yield.
(a) Department of Plant Biology, University Of Minnesota (b) Department of Agronomy & Plant Genetics, University of Minnesota
P02016 Photosynthesis and water relations characteristics and productivity of eight Salix cones in vegetation filter of
wastewater purification system
Aasamaa, Kroot-presenter [email protected](a)
Heinsoo, Katrin (b)
Several characteristics of photosynthesis apparatus and water relations of eight Salix clones growing in vegetation filter of wastewater
purification system in Estonia were studied as related to biomass productivity of the clones. The most productive clones were characterised
with the following characteristics of top foliage leaves: the highest stomatal and hydraulic conductance, the highest stomatal sensitivity to
an increase in light intensity, the highest net assimilation rate both under limiting and under saturated carbon dioxide concentration, the
highest chlorophyll content per leaf area and per leaf dry mass, the highest relation between maximum (i.e., CO2 - and light-saturated) net
assimilation rate and carboxylation efficiency, and the lowest stomatal sensitivity to an increase in leaf water potential, the lowest leaf water
potential and leaf water content per dry weight, and the lowest carboxylation efficiency. Also, the vertical gradient of almost all leaf
characteristics was the smallest in the most productive clones. The characteristics of photosynthesis apparatus correlated with the
productivity stronger than the characteristics of water relations. Productivity correlated most strongly with the CO2 - and light-saturated net
assimilation rate and with the relation between the saturated net assimilation rate and carboxylation efficiency. It was concluded that the
latter characteristics can be used as markers in future selection of most productive clones and species for vegetation filters of wastewater
purification systems in Estonian (temperate maritime) climate.
(a) Estonian University Of Life Sciences, Institute of Forestry and Rural Engineering, Department of Silviculture (b) Estonian University of
Life Sciences, Institute of Agricultural and Environmental Sciences, Department of Botany
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P02017 Development and validation of a tobacco transient expression system for expression and characterization of plant
produced cellulases
Azhakanandam, Kasi-presenter [email protected](a)
Miles, Stacy (a)
Chilton, Mary-Dell (a)
DeBrecht, Andrew
(a)
Kim, Myoung (a)
Arellano, Sergio (a)
Oeller, Paul (a)
Betts, Scott (a)
Warner, Simon (a)
http://www.syngenta.com
A major obstacle to the commercial development of enzymatic conversion of biomass to ethanol is the vast quantity of cellulases required.
Efforts to address this problem have focused on engineering more efficient cellulases. A complementary approach is the engineering of crop
plants to express cellulases to high levels. To facilitate the development of cellulase-expressing crops, we are developing a viral transient
expression system for tobacco to enable the rapid in planta screening of DNA vectors encoding cellulases. We have expressed a fungal
cellobiohydrolase I (CBH1) gene in both stably transformed (transgenic) and transiently transformed (agroinfiltrated) tobacco leaves.
Transgenic tobacco events show accumulation of active CBH1 in leaf tissue when the enzyme is targeted to the ER or vacuole. Results from
the transient system with the same gene show a similar pattern of protein accumulation as seen in the transgenic plants. Analysis of
extracts of agroinfiltrated leaf tissue shows the presence of CBH1 activity on both soluble and insoluble (cellulosic) substrates. The rapid
expression of CBH1 in tobacco leaves will shorten considerably the time required to evaluate properties such as subcellular targeting,
protein stability, and enzyme functionality. The transient system thus allows for screening of high numbers of different cellulase genes and
expression vector components in less than 1 week, compared to months for transgenic events.
(a) Syngenta Biotechnology Inc.
Session P03 – Environmental Physiology
P03001 Roles of FtsH protease in chloroplast biogenesis and protection of photosystems from high temperature stress in
higher plants
Chen, Junping-presenter [email protected](a)
Xin, Zhanguo (a)
Burke, John J. (a)
AtFtsH11 protease gene is essential for Arabidopsis plant to survive at moderate heat stress. Under high and normal light at 21C, ftsh11
mutants were indistinguishable from wild type plants in photosynthesis capability and in overall growth. However, mutant plants display a
host of dramatic changes in photosynthesis, cessation of development, and eventual death if temperatures go beyond 30C. Thermosensitive
phenotypes were observed at all developmental stages and in all green tissues. Cotyledons of mutant seedlings germinated at 21C in the
dark failed to turn green after being transferred to light at 30C. When mutant seedlings were exposed to 30C, chlorophyll content, chl a/b
ratios, PSII quantum yield and ETR decreased significantly while the NPQ and qN increased; the newly formed tissues of mutant plants
failed to turn green while already formed leave became chlorotic over a period of a few day with a Fo continuously increase companied by
decrease in T1/2. TEM showed abnormal chloroplast development in leaf of high temperature stressed mutant plants. These results
suggested that FtsH11 plays critical roles in both the early stages of chloroplast biogenesis and maintaining thermostability of
photosynthetic systems at high temperatures. Overexpression of wildtype FtsH11 genes from Arabidopsis and pea was able to complement
the thermosensitive phenotypes of ftsh11 mutants, suggesting a conserved role of FtsH11 protease in alleviation of high temperature stress
in photosystems of higher plants. The potential substrates of FtsH11 protease in chloroplast are being investigated on 2D Blue native/SDSPAGE gel by comparing changes of photosynthetic complex and chloroplast proteins between mutant and wildtype and between nonstressed and heat stressed mutant plants.
(a) USDA-ARS, Plant Stress and Germplasm Development Unit
P03002 Variation in calcium concentration across leaves of Coriander (Coriandrum sativum L.).
Kerton, Matt-presenter [email protected](a)
Newbury, John (a)
Hand, David (b)
Pritchard, Jeremy (a)
Leaf ion concentration is dependent on import from the xylem in the transpiration stream. This is particularly true for ions such as calcium
that are phloem immobile. Ion distribution was measured using ion chromatography and 45Ca2+. Leaves of coriander plants had elevated
calcium in the leaf centre compared with the leaf edge. Increasing the calcium content of the external solution did not increase leaf calcium
concentration or affect its distribution suggesting regulation within the root. Root pruning, allowing calcium unrestricted entry to the xylem,
short circuited the endodermis and was accompanied by an increase in leaf calcium. However, despite this increase, the spatial variation of
leaf calcium concentration remained unchanged and the difference between inner and outer leaf was exacerbated. Reducing transpiration
by elevating humidity reduced the overall leaf concentration of calcium and abolished the spatial variation. Stomatal density and
evapotranspiration were equal across the leaf surface, suggesting that calcium transport and water movement within the leaf become
uncoupled. This was supported by measurements of leaf resistance to water movement, which were equal between the inner and outer
leaf. Leaf squares isolated from inner or outer leaf accumulated similar amounts of calcium, suggesting that the spatial variation of leaf
calcium concentration was due to differential ion delivery by the leaf transpiration stream rather than a difference in calcium uptake capacity
between the two tissues. An understanding of calcium delivery and distribution by the transpiration stream informs a general understanding
of xylem transport and, specifically in coriander, informs strategies aiming to reduce the incidence of calcium related syndromes such as leaf
tip-burn.
(a) University of Birmingham (b) Humber VHB
P03003 Evidence for low levels of genetic variation among Zostera marina populations from the Atlantic West coast
Campanella, James J.-presenter [email protected](a)
Rosenzweig, Eric B. (a,c)
Smith, Stephanie M. (a)
Bologna,
Paul A.X. (a)
Smalley, John V (b)
Zostera marina (eelgrass), can be found in the North Atlantic on the coast of Europe and the North Arctic, as well as the Pacific. On the
Atlantic west coast this species grows as far south as North Carolina and into northern Canada. The cold waters of these regions support
the habitat needed for the species. Eelgrass is vital to coastal communities. It serves as a food source for many organisms, hatching ground
for fish species, absorbent of water pollutants, and soil stabilizer. Over the last 30 years, the once robust populations of Atlantic west coast
eelgrass have withered into sparse patchy regions due to the effects of pollution, disease, increasing temperatures, and increasing turbidity.
We have analyzed the genetic population structure of Atlantic west coast Zostera, using microsatellite DNA polymorphisms. We have found
that genetic variation, based on effective population sizes and Observed/Expected Heterozygosity, is much lower in the American
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populations studied compared to European Zostera populations. This result suggests severe future problems for the American populations if
gene flow is limited and inbreeding depression occurs. There is strong evidence of bottlenecking in Long Island populations, along with
weaker evidence for such events in Chesapeake Bay. Northern Maine Zostera had the highest effective population size coupled with the
lowest mean number of alleles. Within the nine populations studied there seems to be little apparent gene flow among the west Atlantic
populations.
(a) Montclair State University (b) Bergen County College (c) Wyeth Pharmaceutical Inc.
P03004 Regulation of carbon isotope discrimination during photosynthesis: Results from a global database
Santiago, Louis S-presenter [email protected](a)
Cornwell, W K (b)
Keitel, C (i)
Knohl, A (e)
Martinelli, L A (k)
Reich, P B
(l)
Williams, D G (m)
Westoby, M (c)
Wright, Ian J (c)
Barbour, M M (d)
Buchmann, N (e)
Cernusak, L A (f)
Dawson, T E
(g)
Ellsworth, D S (h)
Farquhar, G D (i)
Griffiths, H (j)
http://plantbiology.ucr.edu/people/?Santiago&show_for=new_window
Within plants utilizing the C3 photosynthetic pathway, discrimination against the stable isotope carbon-13 records information about the
intercellular CO2 concentration during photosynthesis, thereby providing insights into how plants interact with their environment. We
present results from a global database of leaf carbon isotopes containing nearly 4000 species-site combinations and representing
angiosperms, gymnosperms, ferns and bryophytes. Our analyses focus on relationships between climate and carbon isotope discrimination
during photosynthesis, as well as regulation by common indices of leaf physiological function such as maximum photosynthetic rate,
stomatal conductance, specific leaf area, and leaf nitrogen concentration. We determined that approximately 50 % of global variation in leaf
carbon isotope ratios is explained by climate variables. Discrimination (indicating higher CO2 concentration at the site of carboxylation) is
higher at low elevation, high rainfall, warmer temperature, low radiation, and low vapor pressure deficit environments. Our analyses also
demonstrate a positive effect of stomatal conductance on discrimination and negative effects of maximum photosynthetic rate and leaf
nitrogen concentration on discrimination, consistent with current models that account for the balance between the demand for CO2 at the
site of carboxylation and the diffusive supply through stomata. Greater discrimination in leaves with high specific leaf area is consistent with
the expected role of internal conductance across the global dataset. Physiological mechanisms of cross-species variation in leaf carbon
isotopic composition will be further discussed.
(a) University of California, Riverside (b) University of British Columbia (c) Macquarie University (d) Landcare Research (e) ETH Zurich (f)
Charles Darwin University (g) University of California, Berkeley (h) University of Western Sydney (i) Australian National University (j)
University of Cambridge (k) Universidade de Sao Paulo (l) University of Minnesota (m) University of Wyoming
P03005 Cell wall-bound UV-screening compounds explain the high UV tolerance of the Antarctic moss, Ceratodon
purpureus
Robinson, Sharon A.-presenter [email protected](a,b)
Clarke, Laurence J (a)
Chobot, Vladimir (b)
http://www.uow.edu.au/science/biol/academics/UOW009796.html
Ozone depletion has resulted in large increases in springtime ultraviolet-B radiation (UV) over Antarctic plants since the 1970s. Studies of
UV induced DNA damage in three Antarctic moss species have shown Ceratodon purpureus to be the most UV-tolerant, despite possessing
less soluble UV-screening compounds than the co-occurring Bryum pseudotriquetrum. We used alkali extraction of cell wall-bound phenolics
in combination with MeOH extraction of soluble phenolics to determine whether cell wall-bound UV-screens could explain the greater UV
tolerance of C. purpureus. Spectrophotometric studies showed that B. pseudotriquetrum and C. purpureus had equal concentrations of UVscreening compounds overall but these were differentially distributed throughout the cell. Bryum pseudotriquetrum had equal
concentrations of soluble and cell wall-bound UV-screens, whereas almost 80% of these compounds were associated with the cell wall in C.
purpureus. In contrast, the Antarctic endemic Schistidium antarctici only possesses half the total UV-screens of the other species. Confocal
microscopy confirmed the localisation of UV-screens in the three mosses and identification of these compounds by HPLC and LC-MS is
ongoing. The greater investment in cell wall-bound compounds offers C. purpureus a more spatially uniform and potentially more effective
UV screen, consistent with its cosmopolitan distribution and occurrence in many high UV environments. Our results confirm that S. antarctici
has the least UV-screening potential, consistent with the hypothesis that this species may be disadvantaged under continuing springtime
ozone depletion. Cell wall compounds are not usually determined in bryophytes but this research suggests they may be an important
component of the UV defences of lower plants.
(a) University of Wollongong (b) University of Vienna
P03006 Selection and Chemical characterization of high biomass-yielding switchgrass (Panicum virgatum L.) germplasms
in Korea
Eu, Gee Suck-presenter [email protected](a)
Yun, Song Joong (a,b)
Chung, Ill Min (c)
Biomass crops have potential as a source of renewable CO2-neutral energy to ease concerns about fossil fuel consumption. Therefore, there
is an increasing interest in high biomass crops such as switchgrass (Panicum virgatum L.). Switchgrass is a perennial C4 grass that requires
low cost for biomass production.?As switchgrass is not native to Korea, switch grass germplasms were collected and evaluated to select
ones best-adpative to geographical regions of Korea. A total of forty-six switchgrass collections were grown and agronomic performance
was evaluated. Switchgrass collections were divided in three groups, high-, medium-, and low-yielding ones, based on biomass yield.
Composition of organic compounds which could affect conversion to ethanol such as glucose, xylose, crude protein, crude fat, cellulose, and
lignin were analyzed for the two selected lines in each group. Biomass-yield potential of selected lines will be discussed in terms of
agronomic performance and chemical compositions.
(a) College of Agricultural and Life Sciences, Chonbuk National University (b) Experimental Farm, Chonbuk National University (c) College of
Life and Environmental Sciences, Konkuk University
P03007 Effects of container cavity type and size on field performance of container-grown longleaf pine seedlings
Sung, Shi-Jean S.-presenter [email protected](a)
Zarnoch, Stanley J. (b)
Haywood, James D. (a)
Sword Sayer, Mary A. (a)
Container-grown seedlings have been used in most of the artificial regeneration efforts to restore longleaf pine ( Pinus palustris P. Mill.)
ecosystems in the southern U.S for the last two decades. In this study, 27-week-old longleaf pine seedlings, grown in containers of 3 cavity
sizes (small (S), medium (M), and large (L)) and 2 types of cavity coating (Cu and regular (R)), were outplanted in central Louisiana in
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PB 2008
November, 2004. The study was a randomized complete block with 4 replications. Each of the 24 plots had 144 seedlings. More than 90%
of seedlings in all treatments survived after 3 years. At least 90% of the Cu-L, R-L, and Cu-M seedlings had heights exceeding 12 cm and
were considered as coming out of the grass stage in year 3; whereas more than 20% of the R-M, Cu-S, and R-S seedlings remained in the
grass stage. At the end of year 3, the Cu seedlings were larger in height and diameter than the R seedlings. Height and diameter increased
with cavity size. Seasons, but not container treatments, affected photosynthetic rates and chlorophyll contents in year 2 and 3. In
November, 2007, 4 seedlings were excavated from each plot. Compared to the L and M seedlings, the S seedlings had less total biomass
and allocated less to stem and lateral roots and more to needles. The R seedlings had greater cumulative length for the portion of lateral
roots that spiraled around the taproot or grew vertically compressed to the taproot than the Cu seedlings. With more lateral roots extending
horizontally outward and fewer criss-crossing lateral roots, the Cu seedlings might help reduce sapling topping in strong winds which has
been reported more and more in the southern U.S. where container-grown seedlings are used to establish longleaf pine stands.
(a) USDA-Forest Service, Southern Res Sta, Pineville, LA (b) USDA-Forest Service, Southern Res Sta, Asheville, NC
P03008 CO2 enrichment and leaf aging down-regulate both maximum rates of Rubisco carboxylation and mesophyll
conductance in SoyFACE
Sun, Jindong-presenter [email protected](a,b)
Feng, Zhaozhong (a)
Leakey, Andrew (a,b)
Zhu, Xingung (b)
Ort, Donald (a,c)
Several soybean cultivars were grown under 2 levels of CO2, the ambient level of 370 μbar versus the elevated level of 550 μbar, in
SoyFACE (Free Air CO2 Enrichment) in 2007. The responses of CO2 assimilation to CO2, leaf chlorophyll fluorescence, leaf contents of
chlorophyll and carotenoids, and leaf mass area (LMA) were investigated at the reproductive R5 stage versus R6 stage. LMA was 4% higher
in the plants grown under elevated CO2 versus ambient CO2. The contents of Chla, Chlb and carotenoids decreased 8%, 5%, and 12% in
the plants grown under elevated CO2 versus ambient CO2, and decreased 36%, 10% and 18% in R6 versus R5, respectively, indicating
significant senescence occurred at R6 stage and elevated CO2 accelerated the senescence in the absence of drought. The A/Ci responses
were analyzed and compared using various methods (Harley et al, 1992; Long and Bernacchi, 2003; Ethier et al, 2004, 2006; Sharkey et al,
2007). The transition Ci between Rubisco-limited and RuBP-limited photosynthesis increased 24% under elevated CO2 versus ambient CO2,
and increased 14% in R6 versus R5. The maximum rates of electron transport (Jmax) decreased 18% in R6 versus R5, but was similar
between CO2 treatments. The respiration rates in the light (Rd) decreased 15% in R6 versus R5. Rd under elevated CO2 increased in R5,
but decreased in R6 instead. CO2 compensation points (Γ) were significant different among cultivars. In addition, Γ increased under
elevated CO2 versus ambient control, and increased in R6 stage versus R5 stage. The maximum rates of carboxylation ( Vcmax) and
mesophyll conductance (gm) decreased due to leaf aging and elevated CO2. Our results also showed that the sensitivity of Vcmax and gm
to transition Ci varied among various methods.
(a) Institute for Genomic Biology, UIUC, Urbana, IL 61801 (b) Department of Plant Biology, UIUC, Urbana, IL 61801 (c) Photosynthesis
Research Unit, USDA-ARS, Urbana, IL 61801
P03009 Low temperature-induced chloroplast relocation is mediated by a blue light receptor, phototropin 2, in fern
gametophytes
Kodama, Yutaka (a)
Tsuboi, Hidenori (a)
Kagawa, Takatoshi (a)
Wada, Masamitsu-presenter [email protected](a)
Chloroplast relocation movement in response to light has been known more than 100 years (Senn 1908). Chloroplasts move towards weak
light and move away from strong light. Dark-induced relocation, called dark positioning, has also been known. Although the effects of other
stimuli on chloroplast movement have not been well characterized, Senn (1908) examined the effect of cold temperature on chloroplast
positioning in the moss Funaria hygrometrica and reported that chloroplasts showed periclinal and anticlinal positioning at 20-30 degree and
at 1-4 degree under medium intensity light, respectively. Here we confirmed low temperature-induced chloroplast relocation (termed cold
positioning) in prothallial cells of the fern Adiantum capillus-veneris gametophytes. Under weak light condition chloroplasts in prothallial cells
accumulated along the periclinal cell wall at 25 degree, but move toward the anticlinal cell walls when transferred to 4 degree. The
distribution pattern of chloroplasts in cold positioning is similar to that of dark positioning, but chloroplast behaviors during movement are
quite different each other. To understand the mode of chloroplast movement in cold positioning, time-lapse observation was carried out.
Chloroplasts moved at 4 degree as a mass so that the distance among chloroplasts were relatively constant. But in dark positioning at 25
degree, chloroplasts move as an individual basis, so that the distances among chloroplasts change readily. Nuclei also relocate from the
periclinal position to the anticlinal position under cold temperature, whereas mitochondria do not. Cold positioning was not observed in
mutant fern gametophytes defective of the blue light photoreceptor, phototropin 2.
(a) National Institute for Basic Biology
P03010 Transthylakoid proton motive force helps protect photosynthesis against moderate heat stress
Sharkey, Thomas D.-presenter [email protected](a,b)
Zhang, Ru (b)
Heat stress frequently increases cyclic electron transport in leaves; we asked whether cyclic electron flow helps photosynthesis tolerate heat
stress. We used Arabidopsis thaliana mutants presumed deficient in one or the other pathway of cyclic electron flow - crr2 (chlororespiratory
reduction, deficient in chloroplast NAD(P)H dehydrogenase-dependent cyclic flow) and pgr5 (proton gradient regulation, proposed to be
deficient in antimycin-A-sensitive cyclic flow). Temperature of intact leaves was increased from 23oC to 40oC in 2 minutes, held for 30
minutes and then returned to 23oC. Gas exchange, PSII chlorophyll fluorescence, the electrochromic shift (ECS) resulting from an electric
field effect on carotenoid absorption bands, and P700 were measured. Our results indicate that photosynthesis of crr2 and pgr5 mutants
was more sensitive to heat stress and had less ability to recover compared to photosynthesis of the genetic background line gl.
Photosynthesis of pgr5, whose transthylakoid electrical potential was significantly reduced was especially sensitive to heat stress. ECS data
showed that the proton conductance was increased by heat. P700 measurements indicated that P700 became more reduced at high
temperature and the two mutants had much slower P700+ reduction rate during heat treatment and recovery than their background gl. We
propose that a transthylakoid proton motive force protects photosynthesis against moderate heat stress and cyclic electron transport around
PSI may help photosynthesis tolerate heat by maintaining the thylakoid proton motive force.
(a) Michigan State University (b) University of Wisconsin-Madison
P03012 Identification and characterization of phosphate (Pi) responsive genes in gulf ryegrass (Lolium multiflorum L.) by
suppression subtractive hybridization
99
Perumal, Venkatachalam (a)
Padmanabhan, Priya (b)
Kashcahandra, Raghothama (a)
Sahi, Shivendra V-presenter
[email protected](b)
Gulf annual ryegrass (Lolium multiflorum L.) has been identified as a potential accumulator of P as it can extract and concentrate excess P
from soil into their aboveground biomass. To identify genes induced in response to Pi sufficiency and starvation in gulf annual ryegrass,
suppression subtractive hybridization (SSH) technique was used to construct a cDNA library enriched with Pi induced mRNA transcripts.
Differential screening of the library identified 384 putative Pi induced cDNAs. Among these, 116 cDNAs are identified as nonredundant
unigenes of which 108 exhibited high similarities with Genbank entries. Differentially expressed genes selected by subtraction represent
diverse functional categories such as stress/ defense, photosynthesis, transcription regulation, signal transduction, cellular metabolism,
protein synthesis/ degradation and others. The differential expression patterns of 13 selected cDNAs were examined by RNA gel blot
analysis using plant tissues of the gulf ryegrass grown under P-sufficient and P deficient conditions. Results from northern confirmed the
differential expression patterns of these transcripts. Cloning and characterization of full-length cDNAs of three Pi starvation regulated genes
(LmPAP1, LmIPS1 and LmIDS1) were also carried out.
(a) Department of Horticulture and Landscape Architecture, Purdue University (b) Department of Biology, Western Kentucky University
P03013 Functional Analysis of the OsPIF1 Gene Down-regulated by Drought Stress in Rice
Todaka, Daisuke-presenter [email protected](a)
Nakashima, Kazuo (b)
Ito, Yusuke (b)
Ohme-Takagi, Masaru
(c,e)
Shinozaki, Kazuo (d,e)
Yamaguchi-Shinozaki, Kazuko (a,e)
Regulatory mechanisms of abiotic stress responses in rice largely remain unclear. We have identified many abiotic stress-responsive genes
using rice microarrays. Among them, a gene for a bHLH transcription factor was down-regulated by drought stress. The bHLH protein
showed a high sequence homology with Arabidopsis Phytochrome Interacting Factor (PIF), driving us to name the transcription factor
OsPIF1. The level of OsPIF1 mRNA in rice seedlings grown under non-stressed condition with light/dark cycles oscillated in a circadian
manner with peaks at the middle of the light period. Under drought stress condition, expression of OsPIF1 was not elevated during the light
period. OsPIF1 was highly expressed in the node portions of the stem using promoter-GUS analysis. Onion epidermal cells transformed with
YFP:OsPIF1 fusion proteins exhibited the fluorescence in the nucleus, indicating that OsPIF1 proteins were localized in the nucleus.
Overexpression of OsPIF1 in transgenic rice plants promoted internode elongation. In the elongated internode, an enlarged cell size was
observed. In contrast, dominant loss-of-function rice mutants with a chimeric repressor resulted in short length of the internode sections
and the reduced cell size in the sections. These data suggest that OsPIF1 functions as an important regulatory factor of plant height in
response to drought stress. Currently, we are analyzing down-stream genes of OsPIF1 by 44k rice oligoarray system using the transgenic
rice plants. We are also examining whether OsPIF1 proteins function as a transcriptional activator or repressor.
(a) Grad. Sch. Agri. Life Sci., Univ. Tokyo (b) Biol. Resources Div., Jap. Int. Res. Center for Agri. Sci. (c) Gene Function Research Center,
National Institute of Advanced Industrial Sci. and Tec. (d) Plant Sci. Center, riken (e) Core Res. for Evol. Sci. and Tec., Jap. Sci. and Tec.
Agency
P03014 Photosynthesis rates in situ may significantly deviate from measured rates of photosynthesis due to the
measuring-light spectrum used.
Hogewoning, Sander W-presenter [email protected](a)
Trouwborst, Govert (a)
Harbinson, Jeremy (a)
http://www.hpc.wur.nl/UK/
Despite the progress that has been made in biophysical methods, such as chlorophyll fluorescence, gas exchange techniques are still the
gold standard for measuring photosynthesis. Until recently the most commonly used light sources for photosynthesis measurements were
broad-band spectrum quartz-halogen lamps. More recently, red LEDs or mixed red and blue LEDs have also been used. LEDs emit a
relatively narrow-band spectrum. Although it is well known that the spectral quality of irradiance has an influence on photosynthesis, the
consequences of a difference between the light spectrum during plant growth and during measuring photosynthesis is generally not taken
into account. However, accurate measurements of photosynthesis are essential for research comparing different light-spectrum conditions
or in models estimating crop growth based on photosynthesis measurements. Cucumber was grown under different combinations of red and
blue irradiance. We measured photosynthesis/irradiance responses using both the same and different red/blue combinations as during
growth. Actual differences in assimilation due to acclimation to the different spectra during growth, measured with the same spectrum as
during growth, were up to 26%. The differences measured on a single leaf using different measuring-light spectra were up to 30%.
Measurements of light absorptance and ΦPSII for the different measuring-light qualities revealed that the commonly used expression for
calculation of electron transport rate (ETR) is not valid if photosynthesis parameters are measured under a different light spectrum to that
used during growth. (ETR=ΦPSII*PPF*a*PSII/(PSI + PSII)where a=absorbed light fraction and PSII/(PSI + PSII)= the absorptance by PSII
divided by the absorptance of PSI + PSII).
(a) Wageningen University, Plant Sciences department, Horticultural Supply Chains Group
P03015 Chronic and transient effects of nitrogen saturation on root processes in a dominant prairie grass Andropogon
gerardii: Linking gene expression profiles and ecological responses
Surabhi, Giridara-Kumar -presenter [email protected](a)
Sanjay, Kumar (a)
Alam, Nausheen (a)
Caragea, Doina (b,c)
Lu,
Nanyan (c)
Hurt, Amy (a)
Loretta , Johnson (a)
Shah, Jyoti (d)
Tallgrass prairie is amongst the most productive grasslands. In spite of the importance of roots in grazed and burned prairie, effects of
nitrogen (N) on roots remain poorly understood. Our goal is to understand the genomic, molecular and physiological response of roots of
big bluestem (Andropogon gerardii), the dominant grass, to changes in the availability of N. We assess responses to changes in N using
long and short term plots at Konza Prairie, KS. Plots have been chronically treated for 6 yr with 4 levels of N (0, 2.5, 5 and 10gN/m2/yr) and
a parallel set of plots have been treated only once. This design allows us to identify transient and chronic effects and to detect thresholds of
response. We used cross-species microarrays by hybridizing cDNA from big bluestem roots to Zea mays oligonucleotide arrays to identify
genes that are differentially expressed in response to N. 596 genes showed statistically significant differential expression with chronic high
N. Genes that were down regulated include those coding for transcription factors (MADS-box), transporters of nitrate and iron, and growth
regulators. Genes that were up regulated include those involved in defense/stress response, and signaling. 569 genes showed statistically
significant differential gene expression under short-term high N. Up regulated genes include those important in N metabolism (GS) and
antioxidative metabolism (GPX, GST). Down regulated genes include those involved in regulating carbohydrate and N metabolism (14-3-3),
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PB 2008
transporters (sugar, ankyrin-kinase), and growth regulation (auxin). We are exploring the possibility of detecting early signs of N saturation
through gene expression profiles of roots, and linking ecological responses to gene functions under natural environment.
(a) Division of Biology and Ecological Genomics Institute, Kansas State University (b) Department of Computing and Information Sciences,
Kansas State University (c) Bioinformatics Center, Kansas State University (d) Department of Biological Sciences, University of North Texas
Session P04 – Integrative Plant Physiology
P04001 Characterization of Proteins Associated with Rapid Growth in Corn Coleoptiles
Dickerson, Tiffany J. (a)
Hoffmann-Benning, Susanne-presenter [email protected](a)
DelValle, Jacquelyn (a)
Plant cell walls (CW) as well as the overlaying cuticle play a vital role in plant growth, development and the interaction with their
environment. They control the extent and direction of cell expansion and form a barrier against pathogen infection and water loss. As the
cell and tissue expands, CW and cuticle biosynthesis must occur at an increased rate. Ultrastructural examination has revealed the
appearance of osmiophilic particles, which are associated with the outer epidermis of growing tissues, go through the secretory pathway,
and are proteinaceous. Their location and time of appearance suggests that they are related to either CW or cuticle biosynthesis. To
uncover the identity of these particles as well as other components involved in cuticle and CW synthesis we extracted protein from the
epidermis of corn coleoptiles, which had either been depleted of auxin/slow-growing or had been induced to grow rapidly with IAA. Using
SDS-PAGE/in-gel digest/ LC-ESI-MS/MS we identified over 80 proteins in the outer epidermis that are induced during rapid growth. In
addition to 15 proteins that are predicted to be involved in either CW or cuticle biosynthesis or trafficking we found three proteins of
unknown function. Expression patterns of the proteins were confirmed using RT-PCR and microarray analysis. They indicate that several
pLTPs, the reversibly glycosylated polypeptide and its predicted substrate, UDP-glucose pyrophosphorylase, fiber dTDP glucose 4,6
dehydratase and sec15 are induced at the transcriptional and at the protein level, suggesting a major role of those proteins in the regulation
of CW and cuticle synthesis and trafficking, as they relate to cell and organ expansion. Knockout mutants will be used to further
characterize the role of these proteins.
(a) MIchigan State University
P04002 An analytical model for plant tissue respiration based on balanced supply/demand stoichiometries of metabolic
carbon and energy flow
Buckley, Thomas N-presenter [email protected](a,b)
Adams, Mark A (a,b)
Current paradigms for modeling plant respiration express broad insights about important aspects of plant function. For example, scaling leaf
dark respiration to carboxylation capacity reflects the large contribution of protein turnover to respiratory demand; separating respiration
into growth and maintenance terms captures the large respiratory cost of de novo biosynthesis during tissue growth; and calculating NPP as
a fixed proportion of GPP recognises the conservative nature of emergent properties of metabolic regulation and carbon allocation.
However, the analysis and prediction of plant growth and gas exchange are still somewhat hindered by the lack of a theoretical framework
linking respiration rate to the age- and tissue-specific biosynthetic and maintenance demands of different plant tissues, and associated
variations in effects of environmental conditions like temperature and light. We sought to create a model for plant tissue respiration that (i)
predicts effects of tissue-specific biosynthetic demands on non-photosynthetic CO2 and O2 fluxes; (ii) predicts how non-photosynthetic CO2
fluxes are affected by light in leaves; and (iii) has a transparent, extensible and testable basis in specific metabolic stoichiometries relating
supply and demand for ATP, NADH, NADPH, reduced carbon, CO2 and O2. Additionally, as we are not aware of any flux-balance model for
respiration that is compact and tractable enough for incorporation into existing gas exchange models, we sought simplifications that would
permit an analytical solution. We present a first attempt to create such a model, compare its predictions to published data, highlight key
open questions and discuss its potential implications for modeling plant growth and gas exchange.
(a) School of Biological, Earth and Environmental Sciences, The University of New South Wales (b) Bushfire Cooperative Research Centre
P04003 Elevated atmospheric carbon dioxide and ozone concentrations alter LAI through changes in phenology and leaf
growth.
McGrath, Justin M-presenter [email protected](a)
Ainsworth, Elizabeth A (a)
http://www.life.uiuc.edu/ainsworth
Leaves are critical for harvesting light energy, taking up carbon dioxide (CO2) and transpiring water for cooling. Changes in leaf growth,
expansion or development can integrate across the plant canopy and growing season to significantly impact productivity, yield and plantatmosphere fluxes. Although the effects of elevated CO2 concentration ([CO2]) and ozone concentration ([O3]) on leaf expansion have
been studied individually, few studies examine leaf expansion in more realistic simulations of future conditions, with simultaneously elevated
CO2 and O3. Furthermore, previous research has predominantly been done in controlled environments or open-top chambers, which alter
the soil-plant-atmosphere continuum and may alter natural patterns of leaf growth. The purpose of this study is to examine leaf growth and
expansion in plants exposed to elevated [CO2] and elevated [O3] in a field setting to determine how growth parameters such as final leaf
area, leaf number, and growth rate are altered by climate change. It was found that elevated [CO2] and elevated [O3] increased and
decreased leaf area index (LAI), respectively, while the combination treatment increased LAI. Changes in LAI were caused by changes in
both the number of leaves per plant and the individual leaf area. Changes in leaf area were primarily caused by larger and smaller leaf
starting sizes in elevated [CO2] and elevated [O3], respectively. Changes in leaf area were related to cell size and number, where leaves in
elevated [CO2] had more cells and leaves in elevated [O3] had smaller cells. Future research is investigating the molecular basis for these
changes in cell size at elevated [CO2] and elevated [O3].
(a) The University of Illinois, Urbana-Champaign
P04004 Functional characterization of the AtSUC2 sucrose transporter from Arabidopsis thaliana in plant growth and
development by tissue specific complementation assays
Ayre, Brian G-presenter [email protected](a)
Srivastava, Avinash C (a)
Ganesan, Savita (a)
Ismail, Ihab O (a)
http://www.biol.unt.edu/~bgayre/myweb/
AtSUC2 encodes an essential phloem-localized sucrose-proton symporter necessary for sucrose transport from source tissues to sink tissues,
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but its role in distributing sucrose to specific tissues is poorly understood. To evaluate the role of AtSUC2 in sucrose distribution to specific
organs, and to correlate these findings with transport efficiency throughout the whole plant, AtSUC2 cDNA was expressed from various
tissue-specific promoters in a homozygous Atsuc2 mutant background. Expression of AtSUC2 cDNA from 2 kb of AtSUC2 promoter, and
from the strong, phloem-specific promoter from Commelina yellow mottle virus (CoYMVp), was sufficient to restore growth and carbon
partitioning to near wild type levels, even though the latter is not of plant origin. AtSUC2 cDNA expression from the weaker, phloem-specific
rolC promoter of Agrobacterium rhizogenes restored intermediate levels of growth and source tissues accumulated substantial sugar and
starch. The GALACTINOL SYNTHASE promoter of Cucumis melo (CmGAS1p) confers expression only in the minor veins of mature leaves.
Plants expressing AtSUC2 cDNA from CmGAS1p had intermediate growth and accumulated sugar and starch, but ultimately demonstrated
that the only essential function of AtSUC2 in photoassimilate distribution is phloem loading. Expressing AtSUC2 cDNA from the constitutive
Cauliflower mosaic virus 35S promoter, however, did not restore growth to any extent to knockout plants, indicating that AtSUC2 expression
outside the phloem is highly deleterious to whole-plant resource allocation.
(a) University of North Texas, Dept of Biological Sciences
P04005 Photosynthetic pathway influences xylem structure and function in Flaveria (Asteraceae)
Kocacinar, Ferit (b)
McKown, Athena D (c)
Sage, Tammy L (a)
Sage, Rowan F-presenter [email protected](a)
http://www.eeb.utoronto.ca/people/faculty/rsage
Higher water use efficiency (WUE) in C4 plants may allow for greater xylem safety because potential transpiration rates are reduced. To
evaluate this hypothesis, stem hydraulics and anatomy were compared in C3, C3-C4 intermediate, C4-like and C4 species in the genus
Flaveria. The C3 species had the highest leaf specific conductivity (KL) compared to intermediate and C4 species, with the perennial C4 and
C4-like species having the lowest KL values. Specific xylem conductivity was generally highest in the C3 species and lower in intermediate
and C4 species. Xylem vessels were shorter, narrower and more frequent in C3-C4 intermediate and C4 species compared to C3 species,
with the differences being greatest between perennial C3 and C4-like species. WUE values were approximately double in the C4-like and C4
species relative to the C3-C4 and C3 species, and there was a significant negative relationship between WUE and KL. C4-like photosynthesis
arose independently at least twice in Flaveria, and the trends in WUE and KL were consistent in both lineages. In the distinct transitions
from C3-C4 to C4-like and C4 photosynthesis, these changes in WUE and KL support a role for WUE in lowering KL during C4 evolution;
however, any involvement of WUE comes late in the evolutionary sequence. C3-C4 species exhibited reduced KL but little change in WUE
compared to C3 species, indicating partial reduction in hydraulic efficiency preceded increases in WUE.
(a) Department of Ecology and Evolutionary Biology, University Of Toronto, 25 Willcocks Street, Toronto, ON Canada M5S 3B2 (b) Faculty of
Forestry, Kahramanmaras Sutcu Imam University, Merkez 46100 Kahramanmaras, Turkey (c) Department of Ecology and Evolutionary
Biology, University of California, Los Angeles, CA USA 90095-1606
P04006 A DNA element between At4g28630 (ABC transporter ATM1) and At4g28640 (AUX/IAA 11) confers companion-cell
specific expression following the sink-to-source transition in mature minor vein phloem
McGarry, Roisin C.-presenter [email protected](a)
Ayre, Brian G. (a)
The minor vein phloem of mature leaves experience a developmental transition wherein photoassimilate import ceases and export
commences, an event known as the sink to source transition. Despite its physiological significance, very little of this developmental program
is understood. From an Arabidopsis enhancer trap screen, we identified MATURE MINOR VEIN ELEMENT (MMVE) in an intergenic region
between two oppositely oriented genes, ATM1 and AUX/IAA 11. MMVE causes expression in minor vein phloem in a pattern resembling the
sink to source transition. Promoter truncation experiments demonstrate sequences proximal to ATM1 promote minor vein expression
whereas sequences closer to AUX/IAA 11 repress it. Both orientations of the promoter were used to drive expression of CONSTANS,
conferring an early flowering phenotype under non-inductive conditions. When expressing the essential sucrose proton symporter AtSUC2,
MMVE restored growth to Atsuc2 knockout plants. MMVE is the first characterized minor vein specific promoter in the apoplasmic phloem
loader, Arabidopsis, supporting our hypothesis that regulation of minor vein expression is highly conserved irrespective of phloem loading
mechanism.
(a) University of North Texas
P04007 DIFFERENTIAL EXPRESSION LEVELS OF AROMA BIOSYNTHETIC GENES DURING RIPENING OF APRICOT (Prunus
armeniaca L.)
Defilippi, Bruno G.-presenter [email protected](a)
Gonzalez-Aguero, Mauricio (a)
Troncoso, Sebastian (b)
Gudenschwager, Orianne
(a)
Valdes, Hector (a)
Moya-Leon, Maria Alejandra (c)
Campos-Vargas, Reinaldo (a)
One of the most important limiting factors in apricot quality is the loss of flavor after harvest, especially during long term storage. Flavor in
fruits is the unique blend of sugar, acid, phenolic and volatile components that determine their flavor. This complex genetic trait is
manifested in ripe fruit through a complex interaction of metabolic pathways and regulatory circuits that results in the unique fruit flavor
composition, a key to fruit consumption. Despite the importance of aroma in fruit quality, limited information is available at the molecular,
genetic and biochemical level of the genes and pathways that are responsible for the synthesis, accumulation and regulation of volatile
compounds. In order to understand the biological basis of aroma biosynthesis we characterized and differentiated four stages in terms of
maturity parameters, aroma-related volatile compounds, and gene expression levels. We cloned and quantified by qPCR the genes
encoding: alcohol acyl transferase (AAT), alcohol dehydrogenase (ADH), lipoxygenase (LOX) and pyruvate decarboxylase (PDC), key
enzymes involved in alcohol, aldehyde and ester synthesis. As fruit ripening progressed, we observed an increase in adh and aat transcript
levels simultaneously with a decrease in aldehydes (i.e. hexanal and (E)-2-hexenal) and alcohols (i.e. 1-hexanol), and an increase in esters.
Further studies are being performed in terms of characterizing gene expression levels under different environmental conditions during
storage. These studies will contribute to understand overall aroma development during apricot ripening (Funded by FONDECYT 1060179).
(a) Instituto de Investigaciones Agropecuarias-La Platina (b) Facultad de Quimica y Biologia, U. de Santiago de Chile (c) Instituto de
Biologia Vegetal y Biotecnologia, Universidad de Talca
P04008 Identification and characterization of genes differentially expressed during cold storage of cherimoya (Annona
cherimola Mill).
Gonzalez-Aguero, Mauricio A.-presenter [email protected](a)
Gudenschwager, Orianne (a)
Defilippi, Bruno G (a)
Munoz, Carlos
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PB 2008
(a)
Campos-Vargas, Reinaldo (a)
http://www.inia.cl
Cherimoya (Annona cherimola Mill.) is a valuable fruit of the Annonaceae family. However, along with its desirable delicate taste, the high
susceptibility to oxidative events makes it difficult to handle during cold storage and ripening. The isolation of mRNA transcripts encoding
proteins associated with the ripening process is a powerful tool to understand the changes that occur on postharvest. To isolate
differentially expressed genes during cherimoya ripening, a forward suppression subtractive hybridization (SSH) cDNA library was
constructed. SSH was performed with cDNA from fruit at harvest and after 12 days in cold storage. A total of 120 differentially expressed
clones in the SSH library were identified and sequenced; 75 of them are non-redundant expressed cDNAs. Blastx analysis revealed that a
79% of cDNAs had significant sequence homologies with known sequences in the NCBI database. The identified cDNAs encoded proteins
involved in diverse processes such as protein synthesis and modification, signal transduction, endomembrane traffic, transcription and posttranscription, primary metabolism, and other metabolisms. To further characterize differentially expressed genes in the SSH library, RACEPCRs to obtained full length cDNAs were conducted. In addition fruit specific genes were identified when comparing the expression levels in
other vegetal tissues. Real-time PCR analysis for selected genes, which are understood to not be related with cold storage, demonstrated
that all genes were expressed highly during ripening. The information generated in this study provides new clues to understand the
cherimoya ripening process (Funded by PBCT PSD03).
(a) Institute Of Agricultural Research (INIA)
P04009 Integrative physiological model for wheat lifecycle
Fuertes de Mendizabal, Teresa (a)
Gonzalez-Murua, Carmen (a)
Estavillo , Jose M (a)
Gonzalez-Moro, M Begona-presenter
[email protected](a)
Despite the progresses obtained during the past few years in the regulation of the nitrogen and carbon metabolism, many aspects
concerning the efficiency in the nitrogen use by crops remain to be studied. In order to adjust fertiliser application to N demands by the
crop accordingly and avoid the environmental impact, it is necessary to know the integration of metabolic processes involved in the
assimilation, accumulation and internal remobilization of nitrogen in the plant with other physiological changes in the whole plant
throughout the developmental cycle. A physiological model has been established including metabolic processes of assimilation of nutrients
during the vegetative growth and further processes of translocation for grain filling in the reproductive phase, as well as considering the
effect of nitrogen fertilization. According to this physiological model, the application of nitrogen fertilizer during the vegetative phase
increases the synthesis of cytokinins and basic cellular structures, the mesophyll cells density and the size of the vascular cells, and inducing
a foliar expansion and a biomass rise. At cellular level nitrogen fertilization promotes a greater chloroplasts genesis and protein synthesis,
such as Rubisco and cytosolic glutamine synthetase (GS2), as well as the activity of enzymes like nitrate reductase (NR) or GS. During the
grain filling period the high levels of cytokinins, produced as consequence of nitrogen application, induce a delay in foliar senescence, which
is related with a greater maintenance of the integrity of the photosynthetic tissue, as well as with a slower rate of loss of stroma proteins.
(a) Universidad del Pais Vasco/EHU (Spain)
P04010 Characteristics of Polyphenol Oxidases
Hatfield, Ronald D.-presenter [email protected](a)
Sullivan, Michael L (a)
Schmitz, George (a)
http://ars.usda.gov/main/site_main.htm?modecode=36553000
Polyphenol oxidase (PPO, EC 1.14.18.1 or EC 1.10.3.1) catalyzes the oxidation of o-diphenols to o-quinones. Highly reactive o-quinones
couple with phenolics and specific amino acids on proteins to form the characteristic browning products in many wounded fruits, vegetables,
and leaf tissues of plants like red clover and tomato. Production of o-quinones in red clover inhibits post-harvest proteolysis during the
ensiling process. We established a model system to study PPO characteristics by expressing red clover PPO cDNA in alfalfa , which normally
lacks foliar PPO activity and o-diphenols. Activation of PPO occurs upon incubation at room temperature for several days (4-10 days)
resulting in a 40-fold increase in activity. Proteolytic activity against PPO appears to aid in its transition to a more active form but is not
solely dependent upon it. RuBisCo subunits were isolated from alfalfa and used as a model protein to study the interaction of PPO
generated o-quinones with proteins. Treatment of RuBisCo with PPO and caffeic or chlorogenic acid as o-diphenol substrates resulted in
decreased migration of protein bands on SDS page gels. This would implicate PPO generated o-quinones as possible cross-linking agents of
proteins. However, digestion of PPO/caffeic or chlorogenic treated protein with trypsin did not inhibit RuBisCo degradation based on band
migration on SDS-PAGE gels. Closer examination by peptide analysis may reveal minor shifts in the protein degradation patterns and
resulting small peptides. Knowledge of red clover PPOs may improve our understanding of their in vivo function(s) and how their roles in
post-harvest physiology may be exploited.
(a) U.S Dairy Forage Research Center, USDA-ARS
P04011 GFP-Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes
Pelissier, Helene C-presenter [email protected](a)
Peters, Winfried S (b)
Collier, Ray (a)
van Bel , Aart JE (c)
Knoblauch,
Michael (b)
\N
Forisomes are Ca2+-reactive contractile protein bodies that reversibly occlude sieve elements in faboid legumes. They apparently consist of
at least three proteins; candidates have been described as FOR proteins, but their involvement in forisome formation remains to be
demonstrated. We isolated three potentially corresponding genes from Medicago truncatula and expressed their GFP-fusion products in Vicia
faba and Glycine max using the composite plant methodology. In both species, expression of any of the constructs resulted in
homogenously fluorescent forisomes that formed sieve tube plugs upon stimulation; no GFP fluorescence occurred elsewhere. Isolated
fluorescent forisomes reacted to Ca2+ and chelators by contraction and expansion, respectively, and did not lose fluorescence after up to
ten contraction cycles. The three proteins shared numerous conserved motifs between themselves and with hypothetical proteins derived
from the genomes of M. truncatula, Vitis vinifera, and Arabidopsis thaliana. However, they showed neither significant similarities to proteins
of known function nor canonical metal binding motifs. In conclusion, we have demonstrated that FOR-like proteins are components of
forisomes, and that they are encoded by a well-defined gene family with relatives in taxa that lack forisomes. Since the mnemonic FOR
already is registered and in use for unrelated genes, we suggest the acronym SEO (Sieve Element Occlusion) for this family.
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(a) Washington State University, School of Biological Sciences (b) Indiana/Purdue University Fort Wayne, Department of Biology (c) Institut
fur Allgemeine Botanik, Justus-Liebig-Universitat, Senckenbergstr
P04012 Protein Interactions at LTP4 Module in Arabidopsis thaliana During the Floral Transition
Hsiung, Jamie-presenter [email protected](a)
Ben-Ghaly, Labeed (a)
Nickenig, Mario (a)
Huang, Funan (a)
Vellanoweth,
Robert L (a)
Lipid-based signaling pathways are known to control responses to wounding, pathogen infection, and developmental events. Two
extracellular lipid transfer protein genes (LTP3 and LTP4) are significantly up-regulated in leaves as the apical meristem switches to floral
growth in Arabidopsis thaliana. To understand the mechanistic basis for this transcriptional activation, we analyzed the promoters for
conserved sequences and assessed this ability to bind to nuclear factors. A highly conserved, potential cis-regulatory element (the LTP4
Module) located in the promoters of these LTP genes, as well as in a homologous LTP gene in Brassica napus, was identified and used in
electrophoretic mobility shift assays (EMSA) with nuclear extracts prepared from pre-bolt and short-bolt leaves. We found that changes in
protein binding to this element coincide with light induction of floral development. EMSAs also showed that a putative cis-regulatory element
exhibits specific protein:DNA interactions. These EMSA results indicate the presence of a protein that binds to the LTP4 Module during
vegetative and not floral development. Oligonucleotide-directed protein capture studies revealed a single band on a silver stained gel.
Transcriptional activity of the LTP3/4 promoter is also currently being studied using the luciferase reporter gene. Constructs of both the
wildtype LTP3/4 promoter as well as LTP3/4 promoters with Module deletions fused to the luciferase coding region were used for plant
transient transfection and stable transformation. The expression results suggest that the module functions as a transcriptional activator.
(a) Chemistry and Biochemistry Department, California State University at Los Angeles
Session P05 – Maize Biology
P05001 The response of maize (Zea mays L.) roots to synthetic brassinosteroids
Rodriguez-Acosta, Maricela-presenter [email protected](a)
Reyes-Lastiri, Daniel (b)
Zeferino-Diaz, Reyna (b)
FernandezHerrera, Maria Antonieta (c)
Sandoval-Ramirez, Jesus (c)
Meza-Reyes, Socorro (c)
Montiel-Smith, Sara (c)
Maize plays a key role in the Mexican diet. Apart from its importance as food, its use as a bio-ethanol source has increased the demand.
Unfortunately, lack of good agricultural land and good seed necessitates the search for new ways in which yield and biomass can be
increased. Our research group is developing new methods to synthesize brassinosteroid analogues that promote plant growth. These
synthetic substances were tested on plants of Medicago sativa L. and more than 400% increase in biomass was reported in comparison to
the natural homobrassinolide. We investigated the effects that these synthetic brassinosteroids have on maize roots during the first week of
germination. For this we used two maize selections, TL-05B (drought tolerant) and TL-06B (high yield), both supplied by CIMMYT. The
results show that the synthetic brassinosteroids have stronger effects on growth and number of roots in both maize varieties than those
produced by the natural homobrassinolide or untreated grains. They also proved that the magnitude and type of response varies according
to the selection, treatment and concentration used. TL-06B showed the best response to different synthetic brassinosteroids with a larger
response in primary and secondary root and plumule growth in comparison to the effects shown by the natural homobrassinolide.
(a) Herbario y Jardin Botanico. BUAP (b) Facultad de Ingenieria Qumica. BUAP (c) Facultad de Ciencias Quimicas. Benemerita Universidad
Autonoma de Puebla
P05002 Mutator transposition alters the transcriptome and proteome of developing maize anthers
Skibbe, David S-presenter [email protected](a)
Fernandes, John F (a)
Morrow, Darren J (a)
Medzihradszky, Katalin F
(b)
Burlingame, Alma L (b)
Walbot, Virginia (a)
MuDR/Mu are a highly active transposon family moving by either cut only (or cut-and-paste) in strictly somatic tissues or net replicative
transposition (absence of excision alleles) in reproductive tissues. Aside from the MuDR-encoded MURA and MURB proteins, other factors
required for Mu transposition, particularly those contributing to the developmentally specific behavior, have yet to be identified. To address
this question and assess the impact of a highly active transposon on the transcriptome and proteome, RNA and protein was extracted from
anthers at three developmental stages in Mu-active and -inactive stocks. From transcriptome profiling on a 44,000 element oligonucleotide
array we found that approximately 30,000 unique genes are expressed at each stage. Of the ~10% (ca. 3000) differentially regulated
transcripts per stage, there was approximately equal representation by the active or inactive individuals. The effect of Mutator activity on
the host proteome was determined using 2D-Difference Gel Electrophoresis. Of the approximately 2,500 protein spots visualized, Mu-active
and -inactive individuals exhibited 48 statistically significant differentially regulated spots. In contrast to the transcriptome experiments, 47
of the 48 spots were up-regulated in the Mu-active lines. Peptides in 30 spots were sequenced, and the majority encoded genes with
metabolic functions. Twenty-one of these 30 were represented on the oligonucleotide array, and twenty were up-regulated at both the RNA
and protein levels. Interestingly, transcriptome profiling experiments comparing Mu-active lines with or without Mukiller identified unique
sets of differentially expressed genes, suggesting non-equivalence between the silenced state arising spontaneously and induced by
Mukiller.
(a) Stanford University, Department of Biology (b) University of California, San Francisco, Department of Pharmaceutical Chemistry
P05003 Role of a 9-lipoxygenase, ZmLOX5, in maize interactions with fungal pathogens
Park, Yong-Soon-presenter [email protected](a)
Meeley, Robert (b)
Kolomiets, Mike (a)
Lipoxygenases (LOX) are non-heme iron containing dioxygenases that catalyze the hydroperoxidation of polyunsaturated fatty acids into
oxylipins. Up to date, the function of 9-lipoxygenases is little known not only in monocots, but also dicots. Herein we report on the isolation
and functional characterization of maize lipoxygenase (LOX) gene, ZmLOX5. To investigate whether the ZmLOX5 transcripts are spatially
regulated in an organ-specific manner, we have isolated RNA from various maize organs. Northern blotting showed that the ZmLOX5
transcripts accumulate to high levels in apical meristem, tassel, silk, and ear. In leaves, ZmLOX5 is inducible by jasmonic acid (JA), abscisic
acid (ABA), ethylene, and mechanical wounding. Further, to elucidate its function in maize resistance to contamination with maize fungal
pathogens, we generated Mutator transposable insertional mutants of this gene. Colonization of maize seed, stalks, and roots by Aspergillus
flavus, Fusarium verticillioides, and Colletotrichum graminicola is a major limiting factor for maize production because these fungi either
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produce highly harmful mycotoxins or cause stalk and ear rots. Analysis of the lox5 mutants showed that their kernels are significantly more
susceptible to colonization by Aspergillus flavus and Fusarium verticillioides compared with near-isogenic wild types. These two fungi
produce significantly more conidia on the lox5 mutant kernels. Surprisingly, lox5 mutants are more resistant to anthracnose leaf blight
caused by Colletotrichum graminicola. Taken together, our data strongly suggest that defense-related function of this gene is dependent on
the specific fungal pathogen species interacting with specific maize organs.
(a) Texas A&M University (b) Pioneer Hi-Bred International, Inc.
P05004 Initiation of meiosis in maize: Transcriptome profiling of pre-meiotic to early meiotic anthers in three ameiotic1
alleles (am1-1, am1-pra and am1-489)
Nan, Guo L-presenter [email protected](a)
Wang, Rachel (b)
Fernandes, John (a)
Cande, Zacheus (b)
Walbot, Virginia (a)
Meiosis is crucial to ensure gamete production and successful fertilization. In anthers the meiotic products develop into pollen grains. The
goal here is to study the transition into and maintenance of meiosis in maize anthers. In wild type pre-meiotic maize anthers, which are
composed of 5 cell types (epidermis, endothecium, middle layer, tapetum and pollen mother cell), ~35,000 genes (about 70% of the
genome) are expressed. The huge collection of existing and newly identified male sterile mutants will be our entry to understand the
complex orchestration of gene expression during anther development. Through a cytology screen, cloning of the identified genes, and
transcriptome/proteome profiling of selected male sterile mutants, we should define most processes. For example, ameiotic1 (am1) is a
gate-keeper to meiosis. Am1 controls the developmental switch from vegetative to reproductive stage in both male and female flowers. Am1
encodes a pioneer protein that regulates meiotic chromosome architecture. Male meiocytes in most am1 background undergo mitosis
instead. Global transcriptome profiles of staged anthers from three alleles (am1-1, am1-pra, and am1-489) with different degrees of meiotic
arrest were compared with four biological replicas from independent mutant plants on custom 4 x 44K 60-mer Agilent maize arrays.
Differentially expressed genes at various developmental stages in each mutant background were analyzed. All the transcriptome profiles
from previously completed microarray experiments, msca1, ms23, mac1, ms8, and ms32 (in progress), will ultimately be compiled and
analyzed together. This project is funded by the NSF 2007-2012.
(a) Stanford University (b) University of California, Berkeley
P05005 Characterization of two high-molecular weight complexes containing multiple starch biosynthetic enzymes from
developing maize endosperm
Hennen-Bierwagen, Tracie A.-presenter [email protected](a)
James, Martha G. (a)
Myers, Alan M. (a)
http://www.iastate.edu
To explain synthetic phenotypes and pleiotropic effects observed in maize mutants, we propose starch biosynthetic enzyme functions are
coordinated through physical association in multi-subunit complexes. Previous work demonstrated pair-wise interactions between specific
starch synthases (SSs) and starch branching enzymes (BEs) using yeast two-hybrid tests, immunoprecipitation, and affinity purification
using fusion-tagged recombinant proteins. In this study gel permeation chromatography was used to separate components present in wild
type maize endosperm soluble extracts. Fractions were then examined for the presence of SSIIa, SSIII, BEI, BEIIa, and BEIIb by
immunoblot analyses. Three elution peaks containing starch biosynthetic enzymes were observed, a presumed monomer fraction at
approximately 80 kDa, and two different high molecular weight forms at approximately 300 kDa (C300) and 600 kDa (C600). SSIIa, BEIIa,
and BEIIb were present in C300, and these three proteins, along with SSIII, were present in C600. Both high molecular weight peaks were
present in 1 M, 150 mM, and no NaCl conditions. At 1 M NaCl an increase of signal intensity for C600 components was observed, suggesting
that the hydrophobic effect is significantly involved in complex stability. C300 and C600 formation is unlikely due to random aggregation
because in contrast to BEIIa and BEIIb, the BEI isoform was observed exclusively as a monomer. Analysis of mutant extracts revealed SSIIa
is required for BEIIa and BEIIb inclusion in C300 and SSIII is necessary for SSIIa, BEIIa, and BEIIb assembly into C600. These analyses will
further define the role of specific enzymes in determining amylopectin structure required to form crystalline starch.
(a) Iowa State University, Dept. Biochemistry, Biophysics, & Mol. Biology
P05006 TIE-DYED1 localizes to the membrane of the endoplasmic reticulum and co-localizes with SUCROSE
TRANSPORTER1
Braun, David-presenter [email protected](a)
Slewinski, Tom (a)
Baker, R. Frank (a)
The Tie-dyed1 (Tdy1) gene encodes a novel transmembrane protein that we hypothesize plays an important role in carbon partitioning in
maize leaves. As one approach to characterize the function of the gene, we are determining its expression pattern at the tissue, cellular and
subcellular levels. Expression analyses determined that Tdy1 mRNA is exclusively present in the phloem of all tissue types. To determine
where in the cell the TDY1 protein resides, we produced translational fusions of TDY1 to the fluorescent reporter proteins YFP or RFP. Coexpression with known subcellular markers indicates that TDY1 localizes to the endoplasmic reticulum. When TDY1-RFP is co-expressed with
a maize sucrose transporter translationally fused to YFP (ZMSUT1-YFP), we observe that both proteins co-localize to the ER membrane
while ZMSUT1 also localizes to small mobile bodies. RNA in situ hybridizations also localize ZmSut1 transcripts to developing phloem cells
revealing an overlapping expression pattern with Tdy1. We hypothesize that TDY1 may control carbon partitioning by interacting with or
regulating ZMSUT1 within phloem tissue.
(a) Pennsylvania State University
P05007 Comparative proteomics of mesophyll and bundle sheath of C3 and C4 chloroplast envelopes
Manandhar-Shrestha, Kalpana-presenter [email protected](a)
Braeutigam, Andrea (a,b)
Hoffmann-Benning, Susanne (a)
Weber,
Andreas (b,a)
The chloroplast envelope represents the interface between the metabolic networks of the cytosol and plastids. Metabolic transport proteins
would be of particular importance in the case of the C4 plant e.g. maize (Zea mays) where CO2 accumulation and other C4-specific
metabolic fluxes are compartmentalized in bundle sheath and mesophyll cells. Yet only a few such transporters have been characterized at
the molecular level. We hypothesized that comparative proteomics of chloroplast envelopes of maize and pea ( Pisum sativum) will reveal
proteins that are enriched in C4 compared to C3 plants, and more specifically, differentially expressed in mesophyll and bundle sheath
chloroplasts. Those could include candidate proteins that control the metabolite fluxes which are enhanced in C4 plastids of maize compared
to chloroplasts of pea and those that direct the metabolite flow between bundle sheath and mesophyll chloroplasts. A qualitative and semi-
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quantitative analysis based on mass spectrometry/ peptide counts of the proteomes of maize mesophyll and bundle sheath chloroplast
envelopes and pea chloroplast envelopes will be shown. We will also show a comparison between maize mesophyll and bundle sheath
chloroplast envelope proteins. We identified several proteins of known and unknown functions that are differentially expressed in maize
mesophyll chloroplast envelopes. Arabidopsis thaliana knock-out mutants deficient in one of our candidate genes display a bleached-leaf
phenotype that is rescued when plants are grown in elevated CO2 or low light conditions. We confirmed the plastid localization with Cterminal GFP fusions. Metabolite analysis suggests a possible role as monocarboxylate transporter.
(a) Michigan State University, E. Lansing, MI (b) Heinrich-Heine University, Duesseldorf, Germany
P05008 MaizeGDB as chromosome walking companion
Schaeffer, Mary L.-presenter [email protected](a,b)
Campbell, Darwin (a,e)
Harper, Lisa (a,d)
Sen, Taner
(a,c)
Seigfried, Trent (a)
Lawrence, Carolyn (a,c)
http://www.maizegdb.org
MaizeGDB, www.maizegdb.org, is the primary repository for genetic and cytogenetic maps, with many details about chromosome markers,
genes, QTL, phenotypic variations and sequences. It links these data to various external resources: GenBank; the EST and GSS contigs at
PlantGDB, www.plantgdb.org and Dana Farber (previously at TIGR), compbio.dfci.harvard.edu; the FPC BAC contig assemblies at Arizona
www.genome.arizona.edu and their sequenced counterpart at the Maize Sequencing Project, www.maizesequence.org; and the SNP allele
alignments at Panzea, www.panzea.org. The focus of this poster is usage examples, targeting groups interested in chromosome walking to
sequences encoding a phenotypic trait of interest and groups that use reverse genetics to discover function. The examples use the current
tools, although we are working to add a sequence-based genome browser shortly after the B73 sequencing project is completed this year.
Based on a community survey, we will be using GBrowse, also recently adapted by TAIR. In addition we summarize recently added genetic
and cytogenetic map data, which include the first new generation SNP maps from the Maize Diversity Project; additional INDEL mappings
from Pat Schnable; data from the TILLING Project; and RNAi resources and data from the Maize Chromatin project. Researchers are invited
to add their own data using our community curation tools. For larger datasets, please contact Carolyn Lawrence directly. Assistance in using
MaizeGDB is available by on-line tutorials, or direct contact. Email inqueries are typically answered within 24 hours. In addition, researchers
may request a MaizeGDB site visit for more extensive assistance; we currently schedule 3 visits/year from an expert curator for this
purpose. Funded by the USDA ARS.
(a) USDA-Agricultural Research Service (b) University of Missouri (c) Iowa State University (d) University of California Berkeley (e) Authors
listed alphabetically except PI (last) and presenter (first).
P05009 Ammonium fertilization reduces the salinity effect on the growth of maize
Del Castillo-Garza, Miren B (c)
Bastias, Elizabeth (b)
Gonzalez-Moro, M Begona (a)
Gonzalez-Murua, Carmen-presenter
[email protected](a)
Ammonium availability is soils could be more constant in both time and space than that of nitrate, which can be easily leached following
rainfall. However, the importance of ammonium as a direct source of N for plant growth has been substancially underestimated, since
ammonium toxicity has been described in a large number of agronomic species. Another problem to which nowadays agriculture has to face
is the progressive salinization of crop soils. The response of plant growth under saline conditions varies according to whether the nitrogen is
supplied as nitrate or as ammonium, and also depends on plant species. In this work the response of maize to ammonium nutrition and
salinity is studied in two cultivars, the commercial hybrid Zea mays L. benicia and the salt-tolerant Zea mays L. amylacea, a native ecotype
from Lluta valley (Arica-Chile). The tolerance of both cultivars to ammonium is due to in part to a compartmentation of ammonium in roots,
avoiding any accumulation in shoots, and an efficient assimilation of ammonium by glutamine synthetase (GS) and glutamate
dehydrogenase (GDH), thanks to the availability of carbohydrates in this organ. Under saline conditions, the commercial variety reduced
slightly its growth and nitrogen content, while the growth of the tolerant ecotype was stimulated. In the amylacea cultivar salinity
stimulated a higher uptake of Na and Cl ions, and even more under ammonium nutrition, probably to carry out an osmotic adjustment,
while the commercial variety benicia induced an earlier accumulation of proline. The stimulation of GS and GDH in roots under saline
conditions would explicate, in part, the adaptation to salt stress of the amylacea ecotype
(a) Universidad del Pais Vasco/EHU (Spain) (b) Universidad de Tarapaca (Chile) (c) Estacion Experimental de Aula Dei, Consejo Superior de
Investigaciones Cientificas (Spain)
P05010 Potential Anthranilate Modifying Enzymes of Maize Mutant bf-1
Pinkerton, Terrence S-presenter [email protected](a)
Dowd, Patrick F (a)
Seedlings of maize mutant bf-1 exhibit blue fluorescence and a distinct grape odor due to an accumulation of methyl anthranilate and other
anthranilate related compounds. bf-1 also expresses a feedback insensitive anthranilate synthase. Previously we identified a unique
mutation in anthranilate synthase expressed in bf-1 seedlings. While transgenic expression of this mutation in maize did result in some
fluorescence in transformant plants, it did not result in an odor phenotype like that seen in bf-1 plants. Blue fluorescent mutants of
Arabidopsis have been shown to be dependent on a salicylic acid UDP-glucosyltransferase. Because of the lack of strong phenotype in
transgenic maize plants we are investigating potential anthranilate modifying enzymes in bf-1 maize. One salicylic acid UDPglucosyltransferase and three potential salicylic acid carboxymethyltransferases were identified from maize genomic sequences. All four
potential genes were cloned from genomic DNA and sequenced. RT-PCR was also run on cDNA generated from bf-1 seedling mRNA and two
of the carboxymethyltransferase sequences were detected. Characterization of the modifying enzyme gene sequences from bf-1 will be
presented along with comparison to sequences from non-mutant maize lines and other plant species. Expression of the potential genes in
bf-1 seedlings and in maize lines treated with a compound shown to induce hypersensitive response will be also be presented. The
identification and characterization of these genes could potentially add a scent/fluorescence marker when used in conjunction with a
tryptophan resistant anthranilate synthase as a selectable marker. The accumulation of metabolites of anthranilate and salicylate could also
influence hypersensitive response and resistance to insect pest.
(a) National Center for Agriculure Utilization Research, ARS/USDA
P05011 Modulation of maize endosperm starch content by phosphorylation-dependent association of starch synthase III
with a specific 14-3-3 regulatory protein
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PB 2008
Lin, Qiaohui M (a)
Hennen-Bierwagen, Tracie A (a)
James, Martha G (a)
Myers, Alan M-presenter [email protected](a)
The starch synthase (SS) enzyme SSIII, the product of the maize gene dull1 (du1), serves catalytic and regulatory roles in endosperm
starch biosynthesis. SSIII co-purifies with other starch biosynthetic enzymes including SSI, SSII, and branching enzymes BEIIa and BEIIb,
and interacts directly with several of these proteins in yeast nuclei. This study further demonstrates such associations by affinity purification
using specific SSIII fragments as bait, by reconstitution using recombinant proteins, and from the finding that anti-SSIII antibodies coimmunopreciptate BEI, BEIIa, BEIIb, and SSI. SSIII also co-immunopreciptates with the 14-3-3 protein designated as GF14-6, a member of
a class of regulatory factors that bind specific phosphorylated threonine residues. Co-immunoprecipitation with SSIII of 14-3-3, BEIIa, or
BEIIb was eliminated by alkaline phosphatase treatment, indicating phosphorylation-dependent binding. General down-regulation of 14-3-3
expression in Arabidopsis is known to cause increased leaf starch content, suggesting that this specific 14-3-3 protein may regulate
endosperm starch levels through control of SSIII function. A mutant du1 allele that changes a potential 14-3-3 target threonie to an alanine
was introduced into transgenic maize plants lacking endogenous SSIII. The mutant SSIII complemented the native du1-M3 null allele with
regard to starch structure, and 14-3-3 failed to co-immunoprecipitate with SSIII from extracts of the transgenic plants. Starch content in
endosperm of the transgenic kernels was increased by approximately 5% compared to wild type. These data indicate that phosphorylationdependent association between this specific 14-3-3 protein and SSIII is a negative regulatory mechanism for control of starch content in
maize endosperm.
(a) Iowa State University
Session P06 – Tomato & Solanaceous Species
P06001 Common and unique regulation of sympodial shoot development in pepper and tomato
Cohen, Oded (a)
Borovsky, Yelena (a)
Eshed, Yuval (b)
Paran, Ilan-presenter [email protected](a)
Pepper and tomato are both closely related Solanaceae species with sympodial shoot development i.e., their shoot is terminated by a
flower. In pepper two sympodial shoots are developed after bifurcation of the primary stem, while tomato has a single shoot. In pepper,
each sympodial unit consists of two leaves and a single terminal flower while in tomato, each unit consists of three leaves and an
inflorescence. These differences account for the bushy pepper and the vine type tomato growth. We studied mutants impaired in
homologous genes affecting growth habit in both species. We found that fasciculate (fa), a pepper mutation characterized by determinate
growth is homologous to self pruning (sp) that causes precocious termination of sympodial shoots. While in fa the determinate growth is
associated with condensed sympodial units without changing their basic structure, in sp the determinate growth is associated with reduction
of leaf to flower ratio in the sympodial units. A new pepper mutant, late flowering (lfl), is disrupted in the pepper homolog of tomato
JOINTLESS where it is required for normal inflorescence development. Similarly to JOINTLESS, LFL acts to suppress vegetative growth in
the inflorescence meristem. However, while jointless exhibits normal sympodial growth, lfl sympodium has an increased leaf to flower ratio.
Furthermore, multiple flowers developed in lfl, indicate that the single flower in pepper is a reminiscence of an inflorescence and that LFL
along with other factors controls the early termination of the inflorescence meristem. In summary, the comparative analyses of homologous
mutations in the closely related pepper and tomato allow uncovering of mechanisms that control diversification in shoot architecture of the
two species.
(a) Agricultural Research Organization (b) The Weizmann Institute
P06002 Branched-Chain Amino Acid-Derived Flavor Volatiles in Tomato Fruit
Maloney, Greg S-presenter [email protected](a)
Klee, Harry J (a)
Fresh tomato fruit flavor is a combination of the interactions between sugars, acids, soluble solids, and volatile compounds. There are ~20
volatiles which are important for tomato flavor and they include the breakdown products of fatty acids, carotenoids, and amino acids. The
branched chain amino acids are thought to be the precursors to the flavor volatiles 2- and 3-methylbutanol and 2- and 3-methylbutanal, all
of which are important tomato flavor compounds. The pathway from amino acids to volatile compounds has been elucidated in yeast, which
produces these same flavor volatiles in beer, bread, and cheese. Less is known about these pathways in fruit, though there is evidence that
the same pathway occurs in plants. The pathway has three major steps: (1) Deamination of the amino acid to an α-ketoacid by a
transaminase, (2) Decarboxylation of the α-ketoacid to an aldehyde by pyruvate decarboxylase, and (3) Reduction of the aldehyde to a fusel
alcohol via aldehyde dehydrogenase. We have shown the conversion of branched-chain amino acids to these volatiles in tomato fruit by
metabolite feeding coupled to GC-MS. We have identified 6 branched-chain aminotransferases (BCATs) in tomato. The two BCATs most
highly expressed in fruit have been successfully expressed in E. coli. In vitro assays indicate the enzymes use branched-chain amino acids
as substrates. These results reveal that tomato has a branched-chain amino acid catabolism pathway similar to that in yeast. Confirmation
of these in vitro results in planta is underway.
(a) University of Florida
P06003 Cell type specific gene discovery in tomato fruit using laser capture microdissection and pyrosequencing
Matas, Antonio J-presenter [email protected](a)
McQuinn, Ryan (b)
Fei, Zhangjun (b)
Giovannoni, James J (b,c)
Rose, Jocelyn
K.C. (a)
http://labs.plantbio.cornell.edu/rose/
Studies of gene expression in tomato fruit typically use homogenized entire pericarp material and there is generally an implicit assumption,
when describing and interpreting the data that result from such studies, that fruit flesh is uniform. However, the pericarp comprises a range
of cell types and many reports suggest a remarkably different genetic and biochemical landscape among different pericarp zones that is
associated with differential cell development, and both primary and secondary metabolism. Even attempts to address cell type specific
expression in fruit, targeting the skin, have used peels which results in the removal of the cuticle, the outer epidermal cell layer and varying
amounts of hypodermis. We are using a strategy that couples laser-captured microdissection with 454 sequencing to profile cell-type
specific gene expression in tomato fruit during ripening, and similarly in other Solanaceous species. This will generate robust gene
expression data for fruit pericarp tissues that will include new gene sequences currently not available in the tomato EST, microarray or
tomato genome sequencing projects. This integrated systems approach will better define the inventory and diversity of biochemical
pathways, patterns of gene expression and regulatory networks among fruit within the Solanaceae. Direct comparisons of gene expression
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in these tissues, combined with comparison of metabolite data, will also allow the identification of quality related genes, including those
associated with carotenoids, flavonoids, general ripening, specific ripening traits likely differentiated between these tissues, and changes in
cuticle biosynthesis or cell wall architecture.
(a) Department of Plant Biology, Cornell University, Ithaca (b) U.S. Department of Agriculture / Agriculture Research Service, Plant, Soil, and
Nutrition Laboratory, Ithaca, NY (c) Boyce Thompson Institute for Plant Research
P06004 Identification of interspecific reproductive barriers in tomato through comparative proteomics
Lopez Casado, Gloria-presenter [email protected](a)
Covey, Paul (b)
Bedinger, Patricia (b)
Rose, Jocelyn KC (a)
The molecular mechanisms that establish and maintain reproductive barriers between related species of higher plants are not currently
known. This is an important question since manipulation of interspecific barriers could ease the transfer of desirable traits, such as
resistance to abiotic and biotic stresses, or nutritional value, from wild to domesticated species. Since cases of unsuccessful pollination can
be associated with failure of the pollen tube to grow through the stylar cell walls and reach the embryo sac, it is hypothesized that
extracellular proteins and transmembrane proteins, derived from both pollen and pistil, may be critical compatibility determinants. We plan
to use iTRAQ-based comparative proteomics to characterize these protein populations, using a number of Solanum species as a model
system and a series of backcross introgression lines. This technique allows the simultaneous identification and relative quantification of
many hundreds of proteins presented in each tissue. The proteomic analyses will be complemented by pyrosequencing of cDNA populations
from the same tissues, collectively providing insights into the pollen and style proteomes and transcriptomes.
(a) Department of Plant Biology, Cornell University (b) Department of Biology, Colorado State University
P06005 rDNA Sequence Analysis of the Distribution and Abundance of Microorganisms in the Rhizosphere of Cultivated
Tomatoes
Maldonado-Mendoza, Ignacio E-presenter [email protected](a)
Cordero-Ramirez, Jesus Damian (a)
Lopez-Rivera, Raquel
(a)
Martinez-Alvarez, Juan Carlos (a)
http://www.ciidirsinaloa.ipn.mx
Plant root health is the result of interactions between the nutrient status of the plant and pathogenic and non pathogenic organisms which
regulate the ability of pathogens to cause disease or infection. We are currently interested in exploring rhizosphere microorganism diversity
as a source for biocontrol agents. The goal of this study is to utilize rDNA sequencing analysis to learn about the microorganism composition
and abundance of cultivated tomatoes rhizosphere from soils of our region in Guasave, Sinaloa, Mexico. Five samples from the rhizosphere
of field-grown tomatoes from Guasave Valley were taken, dried, sieved and homogenized to create a mixed sample. A 1 g sub-sample was
taken to be processed with the Power Max DNA isolation kit (MoBio). The DNA recovered by this methodology was used to PCR-amplify
hyper-variable regions from the ribosomal DNA. PCR products were cloned into pGEM-T easy vector to generate libraries. A total of 500 and
493 clones from the eukaryotic and prokaryotic rDNA PCR product libraries were obtained and sequenced. Phylogenetic analysis showed
that the main prokaryotic phylla present in these soils were Firmicutes (43%) mainly represented by different Bacillus species, Acidobacteria
(17%) and Proteobacteria (13%). In eukaryotes Ascomycota is the most common phyllum found (62.1%) followed by Chlorophyta (17.7%)
and Basidiomycota (11.4%). The ecological roles and species distribution significance of both eukaryotic and prokaryotic organisms will be
discussed in this presentation. This work was supported by Fundacion Produce Sinaloa, CECyT-Sinaloa and the National Polytechnic Institute
(SIP-2006-0317). JDCR is recipient of PIFI and graduate fellowship support by the IPN.
(a) National Polytechnic Institute CIIDIR-IPN Unidad Sinaloa
P06006 Effect of SUN and OVATE on tomato fruit morphology in different genetic backgrounds
Rodriguez, Gustavo R.-presenter [email protected](a)
Anderson, Claire (a)
Zhang, Na (a)
Moyseenko, Jennifer B
(a)
Gonzalo, Maria Jose (a)
van der Knaap, Esther (a)
The two most important genes contributing to an elongated fruit shape in tomato ( Solanum lycopersicum ) have been identified as SUN and
OVATE . Located on Chr 7, SUN affects shape after fertilization (1) whereas OVATE , Chr 2, affects shape before fertilization (2). The
objective of this work was to analyze the effect of SUN and OVATE on fruit morphology in both wild and cultivated backgrounds and to
determine whether these genes interact. Seven fruit shape attributes were evaluated by Tomato Analyzer Software (3): fruit shape index,
obovoid, width widest position and distal end protrusion as well as internal fruit eccentric attributes such as distal and proximal end
eccentricity and pericarp elongation index. The effect in the wild background was evaluated in NILs of LA1589 (S . pimpinellifolium ) and in
the cultivated tomato background in an intraspecific cross between cvs. Yellow Stuffer and Long John. The strongest effect of SUN on fruit
morphology is to increase the oval shape of the seed part of the fruit whereas the largest effect of OVATE is on the eccentric positioning of
the seed in the fruit. Although fruit shape index is also controlled by OVATE the effect is small in the wild background. Also, it was
determined that SUN and OVATE act independently in the control of tomato fruit shape. Finally, we evaluated a wide set of varieties (i.e.
Heirloom, Spanish, Italian and Latin American lines as well as wild species) that were genotyped for these genes. Varieties carrying SUN
show long pepper or ox-heart fruit shape whereas varieties carrying OVATE are pear-shape, heart or elliptic. References: 1) Xiao et al.
(2008) Science 319:1527-1530. 2) Liu et al. (2002) PNAS 99: 13302-13306. 3.) Brewer et al. (2006) Plant Physiol. 141:15-25. Funded by
NSF DBI 0227541
(a) Department of Horticulture and Crop Science, The Ohio State University/OARDC, Wooster, OH 44691, USA
P06007 Overexpression of the RNA-binding protein affects Morphologies in Tomato (Solanum lycopersicon)
Joung, Young Hee-presenter [email protected](a)
Jeon, Wong-Bae (a)
Kim, Ah Young (a)
You, Young Nim (a)
Park, Sei Hee
(a)
To investigate the function of RNA-binding protein we isolated RNA-binding protein including RNA recognition motifs (RRM) cDNA from hot
pepper (Capsicum annuum) and introduced into tomato (Lycopersicon esculetum cv. Micro-tom). The transformation rate of this gene was
10-folder lower than other genes such as transcription factors, DNA-binding proteins, GUS, GFP etc in tomato plants. Finally, 2 independent
single copy transgenic lines were obtained and conformed by Southern blot analysis and iPCR. In T2 generation of the transgenic seedlings
were divided two groups, one showed abnormal phenotype and the other group showed normal phenotype. The abnormal phenotype
transgenic lines were found out homozygote and normal-look transgenic lines were heterozygote. We observed sever obstacles to growth
and development in homozygote transgenic tomato. This homozygote transgenic lines show short inter-nods, curled leaves, short axial root,
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PB 2008
non-flowering and continuous vegetative growth over one year. But in the heterozygote transgenic lines, there was no difference phenotype
in vegetative growth but it changed not to growth and development after reproductive growth stage so that it had lower flowering and
fruiting rates then wild-type. To know the relative expression levels of the RNA-binding protein gene in the transgenic lines, we used realtime reverse transcription-polymerase chain reaction (RT-PCR) method. Heterozygote transgenic lines showed 3-folder higher mRNA
expression levels than homozygote lines.
(a) School of Biological Sciences and Technology, Chonnam National University
P06008 Development of Fruit specific expression promoter from Tomato Histidine Decarboxylase gene
Kim, Ah Young-presenter [email protected](a)
Jeon, Wong-Bae (a)
You, Young Nim (a)
Park, Sei Hee (a)
Joung, Young
Hee (a)
Development of fruit specific promoter is important for useful protein expression in fruit. According to micro-array analysis, expression level
of the histidine decarboxylase gene (SlHD5) was high in tomato fruit and continuous increase after mature green stage. The histidine
decarboxylase gene was selected to development of tomato fruit specific promoter. The SlHD5 promoter including its 5‘-UTR was isolated
from tomato (Solanum lycopersicum cv. Micro-Tom) genome by genome walking method and this region was sequenced. Analysis of
promoter activity, hexa-his tag fused green fluorescence protein (GFP) gene was used for report system. Tissue-specificity and levels of
protein expression were characterized by transient expression following Agrobacterium infiltration using fruit stylar apex. Fruit specific of
transient GFP expression in tomato have been achieved using the SlHD5 promoter. This promoter should be useful for genetic engineering
of fruit specific expression in Tomato.
(a) School of Biological Sciences and Technology, Chonnam National University
P06009 Development of Seed specific expression promoter from Tomato Amidase gene
You, Young Nim-presenter [email protected](a)
Jeon, Wong-Bae (a)
Kim, Ah Young (a)
Park, Sei Hee (a)
Joung, Young
Hee (a)
Development of seed specific promoter is important for useful protein expression in seed. An amidase gene has been identified that specific
expression in hot pepper seed by micro-array data. According to hot pepper amidase gene sequence, tomato amidase gene was screened
and 2 kb promoter region including its 5‘-UTR of the gene was isolated from tomato (Solanum lycopersicum cv. Micro-Tom) genome by
genome walking method. To analysis promoter activity, amidase promoter was cloned into pCAMBIA 1391Z, which was promoter analysis
binary vector contained β-glucuronidase (GUS) report gene. The recombinant vector was transformed into Arabidopsis using AgrobacteriumMediated vacuum infiltration. Seed specific of GUS activity in Arabidopsis seed have been achieved using the amidase promoter. This
promoter should be useful for genetic engineering of seed specific expression.
(a) School of Biological Sciences and Technology, Chonnam National University
P06010 Development of Root specific expression promoter from Hot pepper Aquaporin gene
Park, Sei Hee-presenter [email protected](a)
Jeon, Wong-Bae (a)
Kim, Ah Young (a)
You, Young Nim (a)
Joung, Young
Hee (a)
An aquaporin protein of hot pepper (Capsicum annuum) is one of tonoplast intrimsic protein. Promoter region of the aquaporin gene was
isolated from hot pepper (C. annuum cv. Bugwang) genome by genome walking method. To analysis promoter activity, the aquaporin
promoter was cloned into pCAMBIA 1391Z, which was promoter analysis binary vector contained β-glucuronidase (GUS) report gene. The
recombinant vector was transformed into Arabidopsis using Agrobacterum-mediacted vacuum infiltration. Root specific of GUS activity in the
transgenic Arabidopsis have been achieved using the aquaporin promoter and the promoter has been shown to express at levels
comparable to the CaMV 35S promoter in root tissue. This promoter should be useful for genetic engineering of root specific expression.
(a) School of Biological Sciences and Technology, Chonnam National University
P06011 TILLING and Eco-TILLING the tomato expansin EXP1 gene
Loeffler, Dayna-presenter [email protected](a)
Hurst, Susan (a)
McGuire, Cate (a)
Barrios, Carrie (a)
Vafeados,
Dionne (a)
http://www.arcadiabio.com
TILLING (Targeting Induced Local Lesions IN Genomes) has been used to successfully isolate novel alleles of known genes from chemically
mutagenized populations. TILLING accelerates plant breeding by introducing genetic diversity to domesticated crops, and facilitating the
discovery of novel functional alleles in genes of interest. Induced mutations can then be used as molecular markers to rapidly introgress the
trait into any cultivar. TILLING technology can also be used to uncover polymorphisms in natural populations, a process that is referred to
as EcoTILLING (Comai et al., 2004). EcoTILLING can reveal potentially useful mutations for molecular breeding, inferring introgression
lineage or identifying haplotypes. Using TILLING, Arcadia Biosciences has generated 220 induced mutations in 19 tomato genes implicated
in fruit shelf life. These shelf life genes represent many functional protein classes, including cell wall disassembly enzymes. One such gene is
the cell wall enzyme, expansin. Antisense reduction of the tomato expansin EXP1 gene increases fruit firmness (Brummell et al., 1999;
Powell et al., 2003). In addition, a recent publication reports reduced biomass accumulation of a fungal pathogen, Botrytis cinerea when
expansin expression is suppressed (Cantu et al., 2008). EcoTILLING of 182 tomato cultivars uncovered one non-coding SNP in the EXP1
gene. By contrast, TILLING was used to identify 9 SNPs in our mutagenized library, including 2 nonsense and 7 missense mutations. Early
results show increased fruit firmness in a knockout expansin line, similar to the results seen in the transgenic antisense expansin line.
Because TILLING is a non-transgenic technology, our nonsense line provides tomato breeders with a novel, non-transgenic source for fruit
firmness.
(a) Arcadia Biosciences, Inc.
P06012 Physical map of quantitative metabolic loci from wild species tomato (Solanum pennellii) *
Kamenetzky, Laura-presenter [email protected](a)
Asis, Ramon (b)
Gonzalez, Virginia (a)
Van Sluys, Marie-Anne
(c)
Giovannoni, Jim (e)
Fernie, Alisdair R (d)
Rossi, Magdalena (c)
Carrari, Fernando (a)
The adoption of tomato varieties selected for their high performance in terms of harvest index has considerably reduced accessibility to
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genetic basis of the Solanum genus. This fact has negatively impacted on the production of alimentary and pharmacological compounds.
The main objective of this work is to determine the genetic bases of key points regulating tomato fruit metabolism. We present here the
construction of a physical map along 5 genomic regions containing metabolic QTL previously mapped on an introgression line population (S.
lycopersicum x S. pennellii). Two genomic libraries from S. pennellii were double-screened with all QTLs co-located markers available at the
Tomato Genome Consortium (www.sgn.cornell.edu). End-sequence analyzes of all anchored clones including gene annotation, contigs
assembling and comparison with the orthologous region of S. lycopersicum allowed the construction of physical maps. Full length sequences
of selected clones containing candidates genes associated with the observed metabolic traits are being generated. The results obtained here
will be presented in the context of the Tomato Genome Project and would render the identification of wild alleles potentially involved in the
tomato fruit quality determination. *This research was supported by the European Commission (EU-SOL Project PL 016214)
(a) Biotech Institute of the National Institute for Agricultural Technology (INTA) (b) Universidad Nacional de Cordoba. Argentina (c)
Departamento de Botanica, Instituto de Bionciencias, Universidade de Sao Paulo. Brasil (d) Max Planck Institute for Molecular Plant
Physiology, Golm, Germany (e) Boyce Thompson Institute for Plant Research, NY, USA.
P06013 Gene Expression profiles of potato tuber meristems treated with compounds that prolong and repress the dormant
state.
Campbell, Michael A.-presenter [email protected](a)
DeWeerd, Jan (b)
Suttle, Jeffrey (c)
The prevention sprouting is of significant economic importance and is often accomplished with chemical applications such as chloropropham
(CIPC). The mechanism of action for CIPC is that of a mitotic inhibitor and herbicide but additional products that suppress sprout growth by
alternate modes would have significant commercial application. The compound 1,4-dimethylnaphthalene (DMN) represents a new class of
sprout inhibitor of unknown mechanism. In this study we examine gene expression using a TIGR cDNA microarray in potato tubers treated
with bromoethane (BE), a compound that breaks dormancy, and the sprout inhibitors CIPC and DMN in order to ascertain the transcriptional
profiles elicted by these compounds. BE and normal dormancy cessation resulted in similar expression profiles particularly in a decrease of
the abscisic acid (ABA) inducible transcripts in the RD22 class and in the increase in transcripts encoding for members of the oxoglutaratedependent family. Cluster analysis of arrays examining gene expression in dormant, nondormant, CIPC, and DMN treated tuber tissues
showed that the dormant and DMN resulted in a profiles with the greatest similarity followed by CIPC treated tissues suggesting that DMN
may function by prolonging the dormant state. It was also demonstrated that more cDNAs were specifically down-regulated in DMN treated
tissues then up-regulated implying that suppression of transcriptional activity is more common to DMN exposure. In comparison to CIPC,
and the nondormant state, few cDNAs were up-regulated exclusively by DMN. ABA analysis did not support the hypothesis that DMN
extends dormancy. Levels of ABA were highest in dormant meristems and declined to the same extent in meristems isolated from nondormant, CIPC- , and DMN-treated tubers.
(a) Penn State Erie, The Behrend College, Erie, PA (b) 1,4 Group Incorporated, Meridian, ID (c) USDA-ARS Northern Crop Sciences
Laboratory, Fargo,ND
P06014 In the search of glutamate sources in ripe tomato fruits
Sorrequieta, Augusto (a)
Ferraro, Gisela (a)
Mortera, Pablo (a)
Boggio, Silvana B. (a)
Valle, Estela M.-presenter
[email protected](a)
http://www.ibr.gov.ar/esp/investigacion/valle.htm
Tomato fruits from cultivated varieties increase free glutamate content significantly during ripening (Boggio et al 2000). In this work we
analyzed the expression level as well as activity of enzymes involved in glutamate metabolism in mature fruits of the cv. Micro-Tom during
the ripening transition. Initially, we established that glutamate was not produced from digestion of endogenous pericarp proteins by any
kind of peptidase present in the mature fruits. Activity analysis of glutamate dehydrogenase (GDH) and enzymes of the GABA shunt during
fruit ripening indicated that all enzymes were active in fruits. In addition, the ratio of aminating to deaminating GDH activity and GABA
transaminase (GABA-T) increased markedly in ripe fruits. From all the enzymes tested, GABA-T activity was the only one that correlated
with transcript levels (one isoform). These enzyme activities and transcripts were also searched in ex-planta ripening fruits. Results showed
that the patterns of enzyme induction were different to those of in-planta matured fruits. Possible metabolic routes contributing to
glutamate accumulation in Micro-Tom fruits during ripening will be discussed. References Boggio et al. 2000 Plant Sci 159:125-133
(a) Instituto de Biologia Molecular y Celular de Rosario (IBR-CONICET), Fac. Cs. Bioq. y Farm. UNR
Session P07 – Tropical Agriculture Biology
P07001 Molecular characterization of a full length cDNA encoding HAD-superfamily hydrolase in oil palm
Namasivayam, Parameswari-presenter [email protected](a)
Thuc, Le Vinh (a)
Ky, Huynh (a)
Ooi, Siew Eng
(b)
Napis, Suhaimi (b)
Ishak , Zamzuri (b)
http://www.biotech.upm.edu.my
A large quantity of ESTs is available from various cDNA libraries of oil palm. The information from oil palm EST databases has been utilized
to identify several interesting sequences for molecular characterization and functional analysis. In this study, molecular characterization of
an EST sequence designated as clone 699 is reported. This clone is predicted to encode a single major open reading frame for a polypeptide
of 244 amino acids. The predicted protein sequence does not have any signal peptide and transmembrane region. Based on Kyte-Doolittle
hydropathy profile, this protein is a soluble protein. The predicted ORF of clone 699 was shown to be 79% identical to a putative HADsuperfamily hydrolase from Oryza sativa (BAD05444), 73% identical to a HAD-superfamily hydrolase subfamily IA, variant 3; Epoxide
hydrolase N-terminal domain-like phosphatase from M. truncatula (ABE82173), and 70% identical to a GS1-like protein from A. thaliana
(AAM67188). Southern analysis showed that clone 699 might be a member of multigene family in the oil palm genome. Gene expression
study by real time RT-PCR showed that this gene was highly expressed in leaves and meristem but lower expression in roots, female flowers
and non-embryogenic and embryogenic calli in comparison to the oil palm cell suspension culture. Currently, functional analysis of clone 699
is carried out in rice.
(a) Universiti Putra Malaysia (UPM) (b) Malaysian Palm Oil Board (MPOB)
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PB 2008
P07002 Analysis of expressed sequence tags (ESTs) from oil palm (Elaeis guineensis Jacq.)
Ho, Chai-Ling-presenter [email protected](a)
Kwan, Yen-Yen (a)
Tan , Siang-Hee (d)
Harikrishna , Kulaveerasingam
(e)
Sharifah Shahrul Rabiah , Syed Alwee (f)
Meilina , Ong Abdullah (b)
Choi , Mei-Chooi (a)
Tee, Sue-Sean (a)
Ng, Wai-Har
(a)
Lim, Kok-Ang (a)
Lee , Yang-Ping (a)
Ooi, Siew-Eng (b)
Lee, Weng-Wah (c)
Tee, Jing-Ming (a)
Oil palm (Elaeis guineensis Jacq.) is the second largest source of edible oil which contributes to approximately 20% of the production of oils
and fats worldwide. In this study, six cDNA libraries from oil palm zygotic embryos, suspension cells, shoot apical meristems, young flowers,
mature flowers and roots, were constructed. We have generated a total of 14537 expressed sequence tags (ESTs) from these libraries, from
which 6464 tentative unique contigs (TUCs) and 2129 singletons were obtained. Approximately 6008 of these tentative unique genes
(TUGs) have significant matches to the non-redundant protein database, from which 2361 were assigned to one or more Gene Ontology
categories. Homologues for proteins involved in flower development, oil biosynthesis, utilization of nitrogen sources, and scavenging of
oxygen radicals, were identified among the EST collection. Majority of them are the first representatives in oil palm, providing opportunities
to explore the cause of epigenetic homeotic flowering abnormality in oil palm, in development of diagnostic assays using gene targeted
markers and discovery of candidate genes related to important agronomic traits of oil palm.
(a) Universiti Putra Malaysia (b) Malaysian Palm Oil Board (MPOB) (c) KOOPrime Technologies (M) Sdn Bhd (d) Sime Plantations Sdn. Bhd.
(e) Sime Darby Technology Centre Sdn. Bhd. (f) Felda Agricultural Services Sdn Bhd.
P07003 Decreased toxicity of cottonseed in pest-protected upland cotton
Romano, Gabriela B.-presenter [email protected](a)
Scheffler, Jodi A. (a)
Cottonseed is a rich source of oil (ca. 21%) and high quality protein (ca. 23%) but its value as food and feed is limited by gossypol, a toxic
polyphenol contained in glands located throughout the plant. Totally glandless varieties have been developed, but not adopted as those
plants are left vulnerable to pests since gossypol is an anti-herbivore defense. In this traditional breeding program an alternative strategy
for selection was adopted which minimized gossypol content in seeds while maintaining glands throughout other plant organs. Previous
studies showed that crosses between varieties with different gland densities and distributions produced a range of glanding patterns so
parents from glanded adapted lines of Gossypium hirsutum L. (STV 7A, JaJo 6078, Acala Maxxa, A1006) were crossed with a glandless
parent (STV 7A gl). F7 and F8 progeny were evaluated visually for presence and abundance of glands in vegetative and reproductive organs
and analyzed with HPLC for total, (+)- and (-)-gossypol in the seed. Selection of genotypes with seed gossypol reduced by 50% to 80%
compared to the glanded parent was possible in all populations; these lines have normal glanding on stems and stigmas and near normal
glanding on the bolls and calyces. Leaves show a reduction in gland numbers from the onset of flowering through maturity, but retain
glands on the veins and leaf margins throughout the season. Since the primary product derived from cotton is its fiber, fiber quality and
yield were also analyzed in selected lines. These new lines should allow the doubling of whole cottonseed in feed for ruminant animals
without detrimental effects. It might also be possible to include cottonseed in fish or poultry rations, further expanding the use of
cottonseed meal.
(a) US Department of Agriculture-Agricultural Research Service
P07004 In vitro micropropagation of red cedar (Cedrela odorata L) via organogenesis employing temporal immersion
bioreactors (BIOMINT).
Pena-Ramirez, Yuri Jorge-presenter [email protected](a)
Juarez-Gomez, Juan (a)
Gomez-Lopez, Lucero del Carmen (a)
Robert,
Manuel L (b)
Gonzalez-Rodriguez, Jose Antonio (a)
Hernandez-Dominguez, Elizabeta (a)
Nila-Mendez, Alejandro Gregorio (a)
http://www.itsacayucan.edu.mx/unibve
Cedrela odorata is a tropical timber tree which is highly valued in the worldwide market. However, high tree production has not been
succesful due to the fact that this kind of tree is highly susceptible to the attack of Hypsipyla grandella, a lepidopter whose larvae attack its
apical meristem, and deform its bole. In nature, there are individuals that show a degree of tolerance against insect attack. However, it has
been difficult to massively produce seeds which posses this tolerant characteristic using traditional breeding technonologies. On the other
hand, in vitro culture technology has a deep impact over species that have a long life cycle, and have not been domesticated yet. C. odorata
is consider one of these species. It has been suggested that the in vitro production of C. odorata individuals that are tolerant to insect
attack is the best strategy to introduce genetic gain in potential regenerating populations. We report here the development, and
optimization of an in vitro culture system for the production of propagules using explants from hypocotyl fragments as well as induced
shoots from twigs collected from mature trees found in commercial plantations of Veracruz, Mexico. Using the TY17 culture medium
(Gonzalez-Rodriguez, and Pena-Ramirez, 2007), it was possible to reach a multiplication index of 4.82 new shoots per explant from
hypocotyl, and a 1.56 multiplication index per explant from twigs. The effect of growing plantlets in BIOMINT bioreactors was evaluated,
and it was found that has a strong impact in the shoot elongation of 100% as well as a root length increment of 300% when compared to
plants developing in semisolid medium. The plants that grew in these bioreactors showed an increase in the ex vitro survival rate (98%).
(a) Instituto Tecnologico Superior de Acayucan (b) Centro de Investigacion Cientifica de Yucatan A.C.
P07005 Molecular and developmental analysis of the fruit abscission zone and shedding process in the oil palm species
Elaeis guineensis and Elaeis oleifera.
Tranbarger, Timothy J.-presenter [email protected](a)
Verdeil, Jean-Luc (b)
Morcillo, Fabienne (a,b)
Jantasuriyarat, Chatchawan
(d)
Tregear, James (a)
Roongsattham, Peerapat (a)
Cros , David (c,e)
Omore, Alphonse (c)
Adam, Helene (a)
Oil palm (Elaeis guineensis) belongs to the Arecaceae family and is the number one source of edible vegetable oil worldwide. Due to a
constant annual increase in demand for vegetable oil for human consumption in addition to the potential use of palm oil as a source of
biofuel, there is increasing pressure for higher yields. One factor that limits yield is the loss due to non-synchronized fruit ripening and
subsequent shedding of the ripest fruit before harvest. We have recently initiated a project with the objective of understanding oil palm fruit
shedding at the histological, physiological and molecular levels. Previous studies indicate that the fruit shedding process in oil palm is
different at the anatomical level from other species. In most fruits, there is a synchronized series of cell separations between the fruit and
the stalk that leads to fruit shedding. The shedding of the oil palm fruit consists of at least two coordinated cell separation stages with a
delay of 1-2 days between the stages. In the present study we examine the abscission zones and physiological factors that affect the cell
separation processes that lead to fruit shedding in the two oil palm species, Elaeis guineensis and Elaeis oleifera. Our results indicate that E.
oleifera is significantly more sensitive to ethylene treatments that induce the cell separation processes leading to fruit shedding. In addition,
111
E. oleifera produces significantly less ethylene during fruit development compared with fruit from E. guineensis. Our results indicate that the
fruit shedding process differs between the two species and will provide an excellent model for understanding the molecular mechanisms
associated with abscission and fruit shedding, a key agronomic character of oil palm.
(a) Institut de Recherche pour le Developpement, UMR DIAPC, Palm Development Group, France (b) Centre de Cooperation Internationale
en Recherche Agronomique pour le Developpement, CIRAD, UMR DAP, PHIV, France (c) Institut national de recherche agricole du Benin,
INRAB, Benin (d) Kasetsart University, Department of Genetics, Thailand (e) Centre de Cooperation Internationale en Recherche
Agronomique pour le Developpement, CIRAD, UPR 28, France
P07007 Changes in the activities of enzymes related to nitrogen and carbohydrate metabolism in leaves of orange (Citrus
sinensis) trees induced for alternate bearing fruits
Shimizu, Milton M-presenter [email protected](a)
Tomaz, Rose MAG (b)
Sekita, Marcelo C (b)
Lagoa, Ana Maria MA
(b)
Mazzafera, Paulo (a)
In this work we induced alternate bearing of fruits in orange trees (Citrus sinensis) by removing young fruits. This was carried out in the
flowering of 2006 and the analyses started September 2007. The numbers of flowers were obtained in 2007 and the number of fruits has
been followed since then. These data showed that alternate bearing was induced. The aim was to obtain information about alternate
production in orange fruits and how carbohydrate and nitrogen compounds influence this process. The activities of enzymes related with the
nitrogen (nitrate reductase, glutamine synthetase, GOGAT) and carbohydrate (sucrose synthase, acid and neutral invertase) metabolism
were analyzed. Carbohydrate and nitrogen enzymes did not differ between induced and non-induced plants until the natural drop of small
fruits, which occurs just before the fruits start to increase in volume. Except GOGAT and glutamine synthetase, which had a decrease of
activity, all the other enzymes showed an increase of activity. The contents of carbohydrates (starch, sucrose, glucose and fructose), amino
acids and nitrogen are being analyzed in these plants.
(a) Instituto de Biologia-Unicamp (b) Instituto Agronomico de Campinas
P07008 Somatic embryogenesis induction, temporary immersion bioreactors (RITA) culture, and genetic transformation of
red cedar (Cedrela odorata L.).
Pena-Ramirez, Yuri Jorge-presenter [email protected](a)
Dominguez-Hernandez, Alfredo (a)
Hernandez-Espinoza, Angel
(a)
Apolinar-Hernandez, Max Mizraim (a)
Gonzalez-Rodriguez, Jose Antonio (a)
Hernandez-Dominguez, Elizabeta (a)
NilaMendez, Alejandro Gregorio (a)
Robert-L, Manuel (b)
http://www.itsacayucan.edu.mx/unibve
C. odorata is a tropical timber tree which is highly valued in the worldwide market due to the fact that the obtained wood has an excellent
quality for the production of fine furniture. However, this species is highly susceptible to the attack of the meliacea shoot borer Hypsipyla
grandella, and this decreases its commercial use. The clonal forestry has demonstrated that it is the best option to obtain, and develop
domesticated mother plantations for high quality seed production, to generate a massive production of plantlets in small areas, and to
establish the basis to develop genetic transformation protocols. In this work, we report a protocol for the induction of primary somatic
embryogenesis of C. odorata using as starting material immature embryos from elite C. odorata trees, and employing a grow culture
medium previously reported [TY17, (Gonzalez-Rodriguez, and Pena-Ramirez, 2007)]. We also evaluated different concentrations of plant
growth regulators to establish the optimal concentration for the induction of secondary somatic emrbyogenesis, and the embryonic
conversion utilizing temporary immersion bioreactors (RITA). Other parameters in the bioreactors were also evaluated like time, and
frequency of immersion for optimal culture conditions. We found that different embryogenic masses reached values up to a 6.2
multiplication factor every 4 weeks. A phenotypic analysis showed that the production of fasciated embryos was not significant. On the
other hand, lethal doses for the antibiotics hygromycin, kanamycin, and spectinomycin were determined. Finally, we reported the
establishment of optimal conditions for the bombardment of embryogenic masses of C. odorata employing nuclear transformation vectors
that contained either the GUS and GFP reporter genes.
(a) Instituto Tecnologico Superior de Acayucan (b) Centro de Investigacion Cientifica de Yucatan A.C.
P07009 Biological and Molecular Characterisation, of Citrus Viroids in Jamaican Citrus Orchards
Bennett, Stacy-Marie L-presenter [email protected](b,a)
Tennant, Paula F (b,c)
McLaughlin, Wayne (d,a)
http://[email protected]
A survey of the six major citrus producing regions of Jamaica was conducted to evaluate the presence and distribution of citrus viroids.
Survey samples were tested in reverse transcriptase-polymerase chain reaction (RT-PCR) with primers specific to Citrus Exocortis Viroid
(CEVd), Citrus bent leaf viroid (CBLVd), Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), and Citrus viroid IV (CVd-IV). Amplicons of the
expected sizes (300-390 bp) for the five groups were detected in samples from all six regions. Complexes of two, three and five viroid
groups were obtained in samples from most of the farms surveyed. CEVd and CVd-IV were the two viroid groups most frequently detected
in infected samples. Survey samples were also bio-indexed for the agents of Exocortis and Cachexia on Citrus volkameriana with Etrog
citron as the indicator plant and on Parson‘s Special Mandarin grafted onto rough lemon rootstock, respectively. Mild and severe symptoms
of Exocortis were observed on Etrog grafts from five of the six regions studied. Notably more severe symptom expression was obtained in
samples from regions with the highest citrus production levels. Only one region, St. Catherine had a sample showing symptoms of Cachexia
disease. The results indicate that Jamaican citrus orchards are reservoirs of citrus viroids. This is the first formal characterization of citrus
viroids in Jamaica.
(a) University of the West Indies (b) Department of Life Sciences (c) Biotechnology Centre (d) Department of Basic Medical Sciences
P07010 Papaya fruit flesh color is determined by gene expression and functional activity of a chromoplast-specific
lycopene β-cyclase, CpCYC-b.
Blas, Andrea L.-presenter [email protected](a,c)
Ming, Ray (b)
Moore, Paul H. (c)
Paull, Robert E (a)
Yu, Qingyi (c)
Papaya breeders have long recognized papaya fruit flesh color to be controlled by a single gene as segregating populations show a 3:1
inheritance of yellow:red fruit flesh color. Previous attempts to identify this gene were unsuccessful. Using a combined candidate gene and
map-based cloning approach a putative chromoplast-specific lycopene β-cyclase gene, CpCYC-b, was identified. CpCYC-b along with four
other genes in the carotenoid biosynthesis pathway was examined for relative gene expression during fruit development and ripening
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PB 2008
between the yellow-fleshed Kapoho and red-fleshed SunUp papaya cultivars. During fruit development, CpCYC-b expression in yellowfleshed Kapoho increases to 11.5-fold higher expression in mature green fruit over leaf tissue while expression in red-fleshed SunUp
remains the same in fruit and leaf tissues. Sequence analysis of the 1484bp predicted coding region of CpCYC-b showed 99.8% sequence
identity between Kapoho and SunUp. A 2bp insertion found in the SunUp CpCYC-b coding region is predicted to result in a frame-shift
mutation and premature stop codon. Transformation of a lycopene-accumulating bacterial line with Kapoho CpCYC-b resulted in a color
change from red (lycopene) to yellow (β-carotene) confirming lycopene β-cyclase activity while transformation with SunUp CpCYC-b failed
to reduce lycopene. It is likely that both regulation of CpCYC-b and functional activity of the gene product affect final fruit flesh color in
papaya. With this data, a sequence based DNA marker is now being developed for marker assisted selection to aid papaya breeding
programs.
(a) University Of Hawaii at Manoa (b) University of Illinois at Urbana-Champaign (c) Hawaii Agriculture Research Center
Session P08 – Heavy Metals & Phytoremediation
P08001 Enhancing Phytoremediation of A Variety of Organic Pollutants
Doty, Sharon L.-presenter [email protected](a)
James, Andrew (a)
Vajzovic, Azra (a)
Singleton, Glenda (a)
Kang,
JunWon (a)
Lee, KeumYoung (a)
Zhang, Gengyun (a)
Bruce, Neil (b)
Schuler, Mary (c)
Strand, Stuart E. (a)
http://faculty.washington.edu/sldoty
Halogenated hydrocarbons, such as trichloroethylene (TCE), are serious environmental contaminants of soil, groundwater, and air. Studies
of the metabolism of this class of pollutants by poplar trees, a genus widely used in phytoremediation applications, has demonstrated that
cytochrome P450 enzymes are involved in the early steps of TCE metabolism. Using microarrays of poplar and Arabidopsis, we have
determined a number of genes that are differentially regulated in response to TCE. Through overexpression of candidate genes and RNAi
experiments in Arabidopsis, we hope to elucidate which of these genes may be directly involved in TCE metabolism. Transgenic plants that
express the genes necessary to metabolize pollutants could lead to profound enhancements in phytoremediation. We have developed
transgenic poplar plants with greatly increased rates of metabolism and removal of these pollutants through the overexpression of
cytochrome P450 2E1. The transgenic poplar plants exhibited increased removal rates of these pollutants from hydroponic solution. When
the plants were exposed to gaseous TCE, chloroform, and benzene, they also demonstrated superior removal of the pollutants from the air.
In view of their large size and extensive root systems, these transgenic poplar may provide the means to effectively remediate sites
contaminated with a variety of pollutants at much faster rates and at lower costs than can be achieved with current conventional
techniques. Another important class of environmental pollutants is the nitroaromatic explosives including TNT and RDX. Expression of
bacterial genes involved in the metabolism of these pollutants in transgenic Arabidopsis, poplar, and grasses led to increased tolerance and
removal rates of TNT and RDX by the transgenic plants.
(a) University of Washington (b) University of York (c) University of Illinois
P08002 The role of plant biomass and root enhancement for metal uptake and phytoextraction
Nehnevajova, Erika-presenter [email protected](a)
Schwitzguebel, Jean-Paul (b)
Schmulling, Thomas (a)
Two key factors determine the efficiency of metal phytoextraction: high biomass production and the bioconcentration factor, which is
defined as the ratio of metal concentration in plant shoots to the concentration in soil. Both can be improved by genetic engineering and
traditional breeding techniques. Classical mutagenesis has been used to improve the metal accumulation and extraction properties of
sunflowers, which were tested on a metal contaminated field. In the second generation, sunflower mutants with enhanced biomass
formation showed a significantly higher (>fivefold) metal extraction (accumulation x biomass) than the control sunflowers for Cd, Zn and Pb
(Nehnevajova et al. 2007). Root enhancement can improve the ability to accumulate specific heavy metals and this may contribute to
efficiently remediate heterogeneously contaminated soils. Therefore the aim of our present study was to explore the relevance of an
eventually enhanced root biomass of the above mentioned sunflower mutants to improve metal uptake and accumulation. Sunflower
mutants of the M5 generation and control plants were grown in the greenhouse on three different sewage sludge soils, which were
contaminated mainly with Cd and Zn, and a non-contaminated control soil. The sunflower mutants showed on the average a more than
50% enhanced root dry weight as compared to the control. In addition, the metal root concentration (mg/kg DW) was in these sunflower
mutants also more than 50% higher than in control plants. The results show that the sunflower mutants do not show only an enhanced
growth of the shoot but also have an enhanced root system. The results are consistent with a relevant role of the root system in
phytoremediation, which deserves further analysis.
(a) Institute of Biology/Applied Genetics, Free University of Berlin (b) Swiss Federal Institute of Technology, Laboratory for Environmental
Biotechnology (LBE), EPFL
P08003 Characterization of the thiol-peptides in the phloem sap of Brassica napus and their role in the long-distance
transport of cadmium
Mendoza-Cozatl, David G-presenter [email protected](a)
Butko, Emerald (a)
Springer, Franziska (b)
Kehr, Julia (b)
Komives,
Elizabeth (c)
Schroeder, Julian (a)
Phytochelatins (PCs) are glutathione-derived peptides that function in heavy metal detoxification in plants and other organisms. Recent
research in Arabidopsis has shown that PCs undergo long-distance transport between roots and shoots (Gong et al., 2003 PNAS 100:10118;
Chen et al., 2006 Plant Physiol 141:108). However, it remains unknown which vascular system, xylem or phloem, mediate PC translocation
and whether PC transport contributes to physiologically relevant long-distance transport of cadmium (Cd) between shoots and roots. To
address these questions, xylem and phloem sap were obtained from Brassica napus to quantitatively analyze which thiol species are present
in response to Cd exposure. High levels of PCs were identified in the phloem sap within 24 hours of Cd exposure using combined mass
spectrometry and fluorescence HPLC analyses. Unexpectedly, the concentration of Cd was more than 4-fold larger in phloem sap compared
to xylem sap. Cd exposure dramatically decreased iron levels in xylem and phloem sap whereas other essential heavy metals such as zinc
and manganese remained unchanged. The high ratios [PCs]/[Cd] and [glutathione]/[Cd] in the phloem sap suggest that PCs and
glutathione (GSH) can function as long distance carriers of Cd. In contrast, only traces of PCs were detected in xylem sap. Our results
suggest that, in addition to directional xylem Cd transport, the phloem functions as a major vascular system for long-distance source to sink
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transport of Cd as PC-Cd and glutathione-Cd complexes. Size-exclusion chromatography of the phloem sap to establish the amount of
cadmium bound to the different types of thiol-containing peptides will also be presented. Supported by NIH grant to JIS and EAK. DMC is a
PEW Latin American Fellow 2006
(a) Biological Sciences, University of California, San Diego (b) Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany (c)
Department of Biochemistry, University of California, San Diego
P08004 An approach for the improved phytoextraction of cadmium.
Butko, Emerald-presenter [email protected](a)
Mendoza-Cozatl, David (a)
Komives, Elizabeth A (b)
Schroeder, Julian I (a)
Heavy metals are released into the environment as byproducts of many industrial processes, and they are detrimental to human health in
trace amounts. Plants naturally accumulate essential metals that exist at trace levels in the soil, and thus phytoextraction has been
proposed as a viable solution for the growing problem of heavy metal contamination of soils. Cadmium and other heavy metals are chelated
by the thiol-peptides glutathione (GSH) and phytochelatins (PCs) intracellularly and sequestered in the vacuole. Aims to improve Cd
retention in plants have focused on the overexpression of enzymes involved in the biosynthesis of thiol-peptides, however these studies
have shown that this approach yields plants that are unexpectedly more sensitive to Cd. In addition, plants preferentially accumulate Cd in
root tissue, which makes the removal of plant-accumulated cadmium from contaminated areas impractical. Another approach has been the
expression of the Saccharomyces cerevisiae GS-Cd transporter YCF1 in the whole plant. Although this approach was successful, it would be
limited by the level of available GSH. An approach will be presented in which these limitations may be circumvented, towards enhancing
tolerance to Cd and its retention in harvestable tissue.
(a) Department of Biology, UC San Diego (b) Department of Chemistry and Biochemistry, UC San Diego
P08005 Overexpression of Arabidopsis tryptophan synthase beta 1 in Arabidopsis and tomato confers tolerance to
cadmium stress
Chan, Ming-Tsair-presenter [email protected](a)
Sanjaya, Sanjaya (a)
Hsiao, Pao-Yuan (a)
Su, Ruey-Chih (b)
Tryptophan is an essential amino acid in humans, and in plants, it plays a major role in the regulation of plant development and defense
responses. However, little is known about tryptophan-mediated cadmium tolerance. Gene expression analysis showed that Arabidopsis
thaliana tryptophan synthase beta 1 is upregulated in plants treated with Cd; hence, we investigated whether this gene is involved in
cadmium tolerance. CaMV 35S promoter-driven AtTSB1 enhanced Trp accumulation and improved Cd tolerance in transgenic Arabidopsis
and tomato plants without increasing the level of Cd. Cd tolerance in transgenic and Trp overproducing mutant plants was associated with
high fresh weight and chlorophyll levels and low lipid peroxidation, as indicated by malondialdehyde 4-hydroxyalkenal (MDA) level, whereas
wild-types developed symptoms of severe chlorosis. Moreover, RT-PCR confirmed that enhanced level of Trp in AtTSB1 transgenic
Arabidopsis plants downregulated AtZIP4 and AtZIP9 metal transporters, which interfered with Cd ion trafficking, a mechanism of
transcriptional regulation that does not exist in wild-type plants. Overexpression of AtTSB1 in transgenic tomato also increase the
endogenous free Trp content accompanied with higher TS-β enzyme activity that wild-type plants. These results implicate that Trp could be
involved in Cd defense.
(a) Academia Sinica, Agricultural Biotechnology Research Center (b) Department of Life Sciences, Fu Jen Catholic University, Taipei, 24205
Taiwan
P08006 A nucleo-cytoplasm co-localized type 2 metallothionein from Prosopis juliflora confers heavy metal tolerance to
transgenic tobacco
Balasundaram, Usha-presenter [email protected](a)
Venkataraman, Gayatri (a)
Parida, Ajay (a)
http://www.mssrf.res.in
Metallothioneins (MTs) are small cysteine rich proteins that bind heavy metals like Cu, Cd and Zn. Their overexpressions has proven to be a
successful strategy for enhancing heavy metal tolerance and are potential candidate genes for generation of transgenic plants for
phytoremediation, thus facilitating cultivation in marginal metal-polluted soils. Over-expression of type 2 MT from Prosopis juliflora, a heavy
metal accumulating phreatophyte, increased the accumulation of cadmium in transgenic tobacco by five fold without significantly affecting
zinc accumulation. PjMT2 bound to cadmium with higher affinity than zinc even in E. coli cells expressing the PjMT2 + Thioredoxin fusion
protein. These results indicate that PjMT2 confer increased heavy metal tolerance in transgenic plants and bacterial systems. Expression
pattern of PjMT2 revealed that it is responsive to oxidative stress but not to heavy metals. The promoter region lacked metal responsive
element (MRE) that is responsible for the regulation of MT gene in the presence of heavy metals. ABA responsive elements were found in
the promoter and PjMT2 was found to be induced under ABA treatment. Epifluorescent microscopy of tobacco plants expressing
PjMT2::mGFP6 fusion protein showed that PjMT2 co-localized in the cytoplasm and nucleus. Information on the site of action of MT2 in the
plant cell would give an idea of its function in vivo. Nuclear localization gives a clue that like animal MT2 genes, plant MTs may also play an
important role during cell proliferation. A detailed validation of nuclear specific localization of MT2 in plants may decipher its role other than
metal homeostasis.
(a) M.S.Swaminathan Research Foundation
P08007 In search of an in-depth understanding of phytoremediation by Phragmites sp.
Davies, Luisa C-presenter [email protected](a)
Cabrita, Goncalo (a)
Ferreira, Renata (a)
Carias, Catia (a)
Novais, Julio
(a)
Martins-Dias, Susete (a)
Phytoremediation of effluents with Phragmites sp. is an environment-friendly, low-cost approach. The specific role of Phragmites in
constructed wetlands, the related molecular biochemical processes, the links between the plants secondary metabolites and the
detoxification pathways are still unclear. To overcome this knowledge gap, a study based on the gene expression of plant enzymes known
to be involved in water-water and ascorbate-glutathione cycles is being carried out. Total RNA was extracted and purified from the leaves
and roots of plants under different stress conditions. Gene expression was screened using primers for peroxidase, catalase, superoxide
dismutase, ascorbate peroxidase, dehydroascorbate and monodehydroascorbate reductase, glutathione peroxidase and glutathione
reductase that were built using regions of high homology among other plants from Poaceae family. Using RT-PCR, the cDNA synthesized
from mRNA was detected by agarose gel electrophoresis. The appearance of new identified bands indicating that genes over-expression
occurred under chemical stress led a first correlation approach between xenobiotic plant stress answer (Reactive Oxygen Species) and
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phytoremediation of chemical pollutant in a constructed wetland. The rapid answer of Phragmites sp. genes concomitantly with increase of
respective enzyme activity was verified. As Phragmites sp. belongs to the Poaceae family, along with rice, wheat, maize, barley and rye, this
genomic approach constitutes a valuable tool for monitoring food safety in the near future, growing in contaminated soils.
(a) Instituto Superior Tecnico/CEBQ
P08008 Deletion of a histidine-rich loop of AtMTP1, a vacuolar Zn2+/H+ antiporter of Arabidopsis thaliana , stimulates the
transport activity
Kawachi, Miki-presenter [email protected](a)
Kobae, Yoshihiro (a)
Mimura, Tetsuro (b)
Meshima, Masayoshi
(a)
http://celld.agr.nagoya-u.ac.jp/Cell_Dynamics_HP_E.html
Arabidopsis thaliana AtMTP1 belong to the cation diffusion facilitator (CDF) family and is localized on the vacuolar membrane. We
investigated the enzymatic kinetics of AtMTP1 by a heterologous expression system in yeast, Saccharomyces cerevisiae, that lacked genes
for vacuolar membrane zinc transporters ZRC1 and COT1. The yeast mutant expressing AtMTP1 heterologously was tolerant to 10 mM
ZnCl2. Active transport of zinc into vacuoles of living yeast cells expressing AtMTP1 was confirmed by a fluorescent zinc indicator FuraZin-1.
Zinc transport was quantitatively analyzed by using vacuolar membrane vesicles prepared from AtMTP1- expressing yeast cells and
radioisotope 65Zn. Active zinc uptake depended on a pH gradient generated by endogenous vacuolar H+-ATPase. The activity was inhibited
by bafilomycin A1, an inhibitor of the H+-ATPase. The Km for Zn2+ and Vmax of AtMTP1 were determined to be 0.30 μM and 1.22
nmol/min/mg, respectively. We prepared a mutant AtMTP1 that lacked the major part (32 residues from 185 to 216) of a long histidine-rich
hydrophilic loop in the central part of AtMTP1. Yeast cells expressing the mutant became hyper resistant to high concentrations of Zn2+ and
resistant to Co2+. The Km and Vmax values were increased two- and 11-fold, respectively. These results indicate that AtMTP1 functions as
a Zn2+/H+ antiporter in vacuoles and that a histidine-rich region is not essential for zinc transport. We propose that a histidine-rich loop
functions as a buffering pocket of Zn2+ and a sensor of the zinc level at the cytoplasmic surface. This loop may be involved in the
maintenance of the level of cytoplasmic Zn2+.
(a) Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University (b) Department of Biology, Faculty of
Science, Kobe University
P08009 Evaluation of the Effect of EDTA and Plant Growth Promoters on Lead Uptake, Translocation, and Oxidative Stress
Response in Medicago sativa
Lopez-Moreno, M. Laura-presenter [email protected](a)
Peralta-Videa, Jose (a)
Gardea-Torresdey, Jorge (a)
Lead bioaccumulates in plants and animals, eventually threatening people. Numerous processes have been applied in order to remove this
heavy metal from contaminated waters and soils. However, these processes are very expensive and time consuming. Phytoextraction, a
phytoremediation technique, appears as a novel cleanup alternative. The aim of this research was to examine whether alfalfa (Medicago
sativa L.), a non-lead hyperaccumulator plant species could increase its phytoextraction capability via the use of EDTA and the
phytohormones indole-3-acetic acid (IAA), gibberellic acid (GA) and kinetin (KN) on lead uptake. Alfalfa plants were exposed to 40 mg Pb
kg-1, EDTA and 1, 10 and 100 μM of the phytohormones IAA, GA, KN, and a mixture of IAA and KN. Lead quantification was performed by
ICP/OES. The addition of EDTA/IAA in Pb treatment significantly increased the Pb accumulation in alfalfa leaves to 2670 mg/kg DW
compared to the Pb accumulation of 93 mg/kg DW in leaves of plants exposed to Pb alone. Plants treated with Pb/EDTA plus KN at 1, 10,
and 100 μM increased the Pb concentrations in leaves to 910, 2340, and 3650 mg/kg DW, respectively. The increase in Pb concentration
respect to the Pb/EDTA treatment was about 190, 660, and 1080%, respectively. Leaves of plants exposed to Pb/EDTA/IAA-KN at 100 μM
had approximately 9,500 mg Pb kg-1 dry DW. The toxicity of lead in alfalfa plants was studied by catalase (CAT), ascorbate peroxidase
(APOX), and total amylase (TAA) activities. X-ray absorption spectroscopic studies demonstrated that Pb(II) was absorbed and translocated
from roots to leaves without any change in oxidation state.
(a) University Of Texas
P08010 Spectroscopic studies of Cr(VI) absorption and reduction by Convolvulus arvensis and Medicago truncatula
Montes-Holguin, Milka O.-presenter [email protected](a)
Peralta-Videa, Jose R (a)
Gardea-Torresdey, Jorge L (a)
Hexavalent chromium is a carcinogenic contaminant with high mobility in soil and water. To optimize the chromium phytoremediation
technique, it is fundamental to evaluate its effects on plant metabolism. In this research, our goal was to study the uptake, reduction, and
transport of chromium by Convolvulus arvensis and Medicago truncatula plants using inductively coupled plasma optical emission
spectroscopy (ICP-OES) and X-ray absorption spectroscopy (XAS). The focus of this work was the chromate transport and reduction from
contaminated media by these two plant species. The concentration of total chromium in Medicago truncatula plants exposed to 40 mg L-1
of Cr(VI) was 2267, 1038, and 505 (mg Cr kg-1) for roots, stems, and leaves, respectively. Convolvulus arvensis plants exposed to 40 mg L1 of Cr(VI) absorbed 2267, 1039 and 505 mg Cr kg-1 in roots, stems, and leaves, respectively. The reduction of Cr(VI) to Cr(III) species
was observed for both plant species as well.
(a) University Of Texas
P08011 The role of TcZNT1 in Zn and Cd hyperaccumulation by Thlaspi caerulescens
Milner, Matthew J-presenter [email protected](a,b)
Kochian, Leon V (b)
Metal hyperaccumulating plant species are plants that are endemic to metalliferous soils and are able to tolerate and accumulate metals in
their above ground tissues to very high concentrations. One such hyperaccumulator, Thlaspi caerulescens, has been widely studied for its
remarkable properties to tolerate toxic levels of zinc (Zn), cadmium (Cd), and sometimes nickel (Ni) in the soil, and accumulate these metals
to very high levels in the shoot. T. caerulescens has the ability to accumulate as much as three percent dry weight Zn and one percent dry
weight Cd in the shoots of the plant with no signs of toxicity. Early molecular investigations in our lab into how this plant functions as a
metal hyperaccumulator led to the identification of TcZNT1 as a gene encoding a high affinity Zn transporter and low affinity Cd transporter
which is expressed at very high levels in the roots of T. caerulescens. While the findings from these earlier studies suggested that TcZNT1
might be involved in root metal uptake from the soil, recent data from our lab indicates that this is not the case. In the current more
detailed ongoing characterization of TcZNT1 and its homolog in Arabidopsis, AtZIP4, we have tried to elucidate the function of these
transporter proteins in the plant and how each may play a role in metal transport, homeostasis, and accumulation of different
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micronutrients/heavy metals. These new findings will be presented.
(a) Cornell University (b) Robert W. Holley Center for Agriculture and Health USDA-ARS Cornell University
P08012 Bioinformatic approach for searching putative metal ion response genes in plant genomes
Valle-Garcia, David-presenter [email protected](a,b)
Meza, Karla (a,b)
Plants are constantly exposed to different biotic and abiotic stimuli. Metal ion response is an specially relevant and complex process in which
several genes are involved. The study of these genes is becoming important for the agriculture due to the accumulation of metallic soil
pollutants all over the world. Although some efforts have been made in order to identify the genes responsible for this process, it has
become necessary to develop a massive bioinformatic approach for the efficient search of these genes.
In the present study a bioinformatic procedure was performed to identify putative metal ion response genes in five important cultivated
plants: wheat, rice, soybean, common bean and grape.
In order to reduce false positive predictions, a search was performed using domain architecture and homology taking as model the known
metal ion response genes of Arabidopsis thaliana. This strategy was chosen because search based only in homology is prompt to mistakes.
The putative presented genes may be important in the elucidation of the complex traits that allow plants to deal with their environment.
Moreover, the characteristics of the found genes could provide insights for the identification of this kind of genes in other plants.
Our search provides a powerful tool and pipeline that allow the identification of many putative genes even when the complete genome
sequence is not available. These genes, many of which had unknown functions, may be useful for leading future basic and biotechnological
research.
(a) Centro de Ciencias Genomicas UNAM (b) Instituto de Biotecnologia UNAM
P08013 Plant regeneration and transformation systems for Se-hyperaccumulators A. bisulcatus, A. racemosus and nonaccumulator A. canadensis
Xie, Jay (Jiahua)-presenter [email protected](a)
Hung, Chiu-Yueh (a)
Selenium (Se) is an essential micronutrient for most organisms, but it can become toxic at high concentrations. Plants with high Seaccumulating capacity are desirable for both Se phytoremediation and cancer chemoprevention. Understanding the mechanisms of which
Se-hyperaccumulators accumulate and tolerate a high level of Se is required to create transgenic plants for environmental restoration and
human health. Currently, functional analysis of Astragalus genes involved in Se-accumulation has been limited due to the lack of
regeneration and transformation systems. We have established plant regeneration and transformation systems for Se-hyperaccumulators A.
bisulcatus, A. racemosus and non-accumulator A. canadensis. About 98.4% to 100% of explants from A. canadensis could produce calluses
with shoots, while those of A. bisulcatus and A. racemosus were less capable, with only about 23.4% to 70.3% producing shoots. The major
limitation of current regeneration system is low rooting rate. Based on our tissue culture system, we have successfully established an
Agrobacterium-mediated transformation system with a bacterial gusA-gene. This transformation system will allow the characterization of
candidate genes involved in Se-accumulation by the suppression in hyperaccumulating plants more precisely than in other model plants.
(a) Department of Pharmaceutical Sciences, North Carolina Central University
P08014 Characterization of a putative phosphate transporter involved in arsenate transport from Hyper-accumulatingplant (Ptreris vittata) leaves.
Hatayama, Masayoshi-presenter [email protected](a)
Inoue , Chihiro (a)
Arsenic is spread in wide range of Asian country such as Bangladesh, India and so forth, and be a cause of skin cancer. Pteris vittata is
kwon for its ability to accumulate highly amount of arsenic to the extent of 2% of the dry weight and expected to be a better tool for
phytoremediation. Previously, EXFAS analysis shows arsenic is mainly existed as an arsenite and a slightly as an arsenate in the stem of the
fern. Thus, it is assumed that arsenic is uptake into the cell by the inorganic form of arsenite and arsenite. Here we report the isolation of
phosphate transporter homologue, PvPHT1;1 and PvPHT1;2, form P. vittata cDNA library with homology cloning technique. Expression
analysis of both two clones was performed with semi-quantitative RT-PCR. As a results, PvPHT1;1 was constitutively expressed at the frond
of P. vittata, whereas PvPHT1;2 was repressed under arsenic conditions at the frond. PvPHT1;1 was investigated for ability of arsenate
uptake compared with AtPHT1;4, phosphate transporter from Arabidopsis thaliana. Both PHT1 transporters were expressed in the yeast cell
under galactose inducible promoter. PvPHT1;1 and AtPHT1;4 uptake arsenate higher than the yeast transformant harboring empty vector.
However, there was no significant difference of the arsenate uptake between two PHT1 transporters.
(a) Tohoku university
P08015 Isolation and characterization of metal hypersensitive Arabidopsis thaliana mutants
Clemens, Stephan-presenter [email protected](a)
Weber, Michael (a)
Deinlein, Ulrich (a)
Stirnweis, Daniel (a)
http://www.pflanzenphysiologie.uni-bayreuth.de/
To date only few metal tolerance factors have been identified in plants. Among them are metal-binding ligands such as phytochelatins and
sequestering or effluxing transporters such as MTPs or HMAs, respectively. Next to nothing is known about the regulation of metal tolerance
mechanisms. We initiated a forward genetic screen in A. thaliana to identify genes contributing to growth under conditions of metal excess.
About 20 mutants were isolated so far representing at least six different loci. Their metal specificity varies. Some are exclusively Zn2+
hypersensitive while others show a stronger than wild type growth inhibition in the presence of a range of metal ions, e.g. Cd2+ and Ni2+.
Also, we observed in one case a partial loss of tolerance towards other abiotic stresses. So far, three of the affected genes have been
mapped. We are in the process of molecularly characterizing the mutants.
(a) University of Bayreuth, Germany
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Session P09 – Reactive Oxygen & Nitric Oxide
P09001 Ion flux signalling during oxidative stress
Shabala, Sergey-presenter [email protected](a)
Cuin, Tracey A. (a)
Nemchinov, Lev G. (b)
Demidchik, Vadim (c)
Changes in membrane transport activity have long been recognised as an important component of ROS signalling in plant cells. Specific
details of such signalling and the molecular identity of key membrane transporters involved in this process are not fully understood. In this
work, a range of electrophysiological and biochemical techniques was used to reveal the role of ion flux signalling in mechanisms underlying
oxidative stress tolerance and cell death in plants. We show that application of ROS (either H2O2 or OH* -generating Cu2+/ascorbate
mixture) to plant tissues results in a massive, dose-dependent efflux of K+. Pharmacological experiments [1] and patch-clamp data [2]
indicate outward-rectifying K+ (KOR) and non-selective cation (NSCC) channels as downstream targets of such signalling. We further show
that expression of animal CED-9 anti-apoptotic gene significantly increases plant oxidative stress tolerance by regulating KOR and NSCC
activity [3], thus providing the first link between ―ion flux signatures‖ and mechanisms involved in regulation of PCD in plants. Finally, we
show that physiologically relevant concentrations of various compatible solutes significantly reduce ROS impact on major ion transporters
[1]. Importantly, a significant reduction in K+ efflux (associated with increased stress tolerance) was found using osmolytes with no
reported free radical scavenging activity has been demonstrated. This indicates that compatible solutes must play other (regulatory) roles in
addition to free radical scavenging in mitigating the damaging effects of oxidative stress. References: [1]Cuin & Shabala (2007) Plant Cell
Environ 30: 875-885; [2] Demidchik et al. (2003) J Cell Sci 116: 81-88; [3] Shabala et al. (2007) Planta 227: 189-197.
(a) University of Tasmania, School of Agricultural Science (b) USDA/ARS, Molecular Plant Pathology Laboratory (c) University of Essex,
Biology Department
P09002 Floral Transition and Nitric Oxide Emission in Floral Structures of Arabidopsis thaliana are Affected in Nitrate
Reductase-Deficient Plants
Seligman, Kelly (a)
Oliveira, Halley C (a)
Pinto-Maglio, Cecilia AF (b)
Salgado, Ione-presenter [email protected](a)
The nitrate reductase (NR)-defective double mutant of Arabidopsis thaliana (nia1 nia2) presents low contents of L-arginine and nitrite and,
consequently, low NO in their leaves than do the wild-type plants. Here we analyzed the effect of the NR mutation on floral induction and
development of A. thaliana, since NO was recently described as one of the signals involved in the flowering process. The NO fluorescent
probes diaminofluorescein diacetate (DAF-2DA) and 1,2-diaminoanthraquinone were used to localize, by fluorescence microscopy, NO
production in the floral structures of A. thaliana during floral development. Data were validated by incubating the intact tissues with the free
form of the fluorescent probe (DAF-2) and quantifying, by fluorescence spectrometry, the DAF-triazole resulted from the reaction of the
probe with NO emitted from the tissues. The results showed that NO is synthesized in specific cells and tissues in the floral structure and its
production increases with the floral development until anthesis: in the gynoecium, NO synthesis occurs only in differentiated stigmatic
papillae and, in the stamen, only pollen grains synthesize NO. Even presenting the same pattern of NO emission in their floral organs, NRdeficient plants emitted less NO. This mutant presents early floral transition, compared to wild-type plants, as measured by the decrease in
the number of days to bolting and anthesis. Recovery of aminoacid levels in nia1 nia2, by irrigating the plants with L-glutamine or L-arginine
during vegetative growth, did not recover NO levels or prevent the earlier flowering phenotype. The results suggest that the decreased
nitrite reductase activity accounts for the early flowering and reduced NO emission in floral organs of the NR-deficient plants.
(a) Universidade Estadual de Campinas (b) Instituto Agronomico de Campinas
P09003 H2O2 oxidizes discrete peptides within peroxisomal catalase and malate synthase
Donaldson, Robert-presenter [email protected](a)
Kwak, Yoon (a)
Anand, Pria (a)
Peroxisomes contain oxidases that produce H2O2 which can result in protein oxidation, specifically carbonylation. To test the vulnerability of
peroxisomal proteins to oxidation, the organelles were isolated from castor bean endosperm that had been incubated with 110 mM H2O2.
When peroxisomes were exposed to this excess H2O2 in vivo the peroxisomal proteins exhibited an increase in carbonylation as detected in
avidin blots of biotin hydrazide derivitized samples. Biotin tagged peptides from trypsin digests of the proteins were analyzed by mass
spectroscopy and compared the masses of the peptides of those from the same protein which had not been biotin tagged and from proteins
not exposed to excess H2O2. A novel JAVA program was created to identify oxidized peptides within catalase (CAT) and malate synthase
(MS). H2O2 exposure was found to increase the activity of CAT, and to increase the number of oxidized peptides found in both CAT and MS.
When an oxidized protein was tagged with biotin hydrazide, several peptides were observed less frequently in the mass spectra than in the
non-oxidized sample of the protein; biotin tagged peptides shift to different masses. CAT had 1O peptides that were affected by exposure to
excess H2O2 and MS had 8. These peptides have definable locations within the proteins. This type of analysis could lead to an
understanding of how sites of oxidation relate to functional alterations, loss of activity, degradation or aggregation. Support: NSF REU
No.0649165
(a) George Washington University
P09004 Nitric oxide regulates shikonin formation in suspension cultured Onosma paniculatum cells
Wu, Shu-Jing (a)
Qi, Jin-Liang (a)
Yang, Yonghua-presenter [email protected](a)
Endogenously occurred nitric oxide (NO) is involved in the regulation of shikonin formation in Onosma paniculatum cells. NO generated after
the cells were inoculated into shikonin production medium, reaching the highest level after 2 d of culture, which is 16 times that of the
beginning, and could be detected by electron paramagnetic resonance within 12 d following inoculation. A nitric oxide synthase (NOS)
inhibitor, N_-Nitro-L-arginine (L-NNA), and a nitrate reductase (NR) inhibitor, sodium azide (SoA), apart from their inhibition on NO
biosynthesis, decreased shikonin formation significantly. This reduction could be alleviated or even abolished by exogenously NO supplied by
sodium nitroprusside (SNP), suggesting that the inhibition of NO biosynthesis resulted in decreased shikonin formation. However, when
endogenous NO biosynthesis was up-regulated by the elicitor from Rhizoctonia cerealis, shikonin production was enhanced furthermore,
showing dependence on the elicitor-induced NO outburst in cells. Gene expression analysis showed that NO could up-regulate the
expression of PAL, LePGT and HMGR, which encode key enzymes in shikonin biosynthesis in cultured cells. These results demonstrated that
NO plays a critical role in shikonin formation in O. paniculatum cells.
(a) Nanjing University
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P09005 Gene expression profiling identifies new determinants of ROS signaling in chilling stress
Einset, John W-presenter [email protected](a)
It has now been demonstrated that application of glycine betaine (GB) to plants can improve tolerance to chilling stress and that this effect
is accompanied by gene expression changes which are required for GBs effect. This finding provides the opportunity to identify new chilling
stress determinants by 1) gene expression profiling with microarrays and northerns in response to GB, followed by 2) functional genetic
confirmation of the involvement of specific GB-regulated genes via mutant studies. Using this approach, three genes have been identified so
far: membrane-trafficking RabA4c (At5g47960), FRO2 ferric reductase (At1g01580) and bZIP transcription factor (At3g62420). At the same
time, these studies showed a close linkage between chilling stress and accumulation of reactive oxygen species, suggesting that chilling
stress involves a ROS signaling pathway. To stimulate further mechanistic studies in relation to the role of ROS in chilling stress, we have
developed a model involving ROS signaling as the molecular mechanism determining chilling sensitivity. According to this model, chilling
stress begins with perception of low temperature by an unknown receptor, followed by activation of membrane NADPH oxidase (NOX),
causing an increase in ROS levels which signals altered gene expression, resulting in inhibited growth under normal growing conditions in
Arabidopsis and in more severe effects in chilling-sensitive plants. The model focuses attention on ROS production/scavenging as well as
membrane trafficking for future studies of the mechanism of chilling tolerance.
(a) Norwegian University of Life Sciences
P09006 Nitrate reductase-dependent nitric oxide synthesis modulates the occurrence of C3 or CAM photosynthesis in
pineapple plants
Freschi, Luciano-presenter [email protected](a)
Rodrigues, Maria A. (a)
Mercier, Helenice (a)
Nitric oxide (NO) has emerged as a key signaling molecule in a variety of physiological processes in plants; however, the mechanisms by
which NO is biosynthesized in plant tissues are still unclear. Several potential sources of NO have been described in plants, but most of the
studies have focused on the NO generation by NO synthase (NOS), nitrate reductase (NR) and mitochondrial electron transport. Since we
have recently demonstrated that NO can mimic the positive effect of abscisic acid (ABA) on the switch from C3-photosynthesis to
Crassulacean acid metabolism (CAM) in pineapple (Ananas comosus) plants, this study attempted to investigate if NO could act as an
intermediate in the ABA signalling cascade required to produce this response. Additionally, the potential biosynthetic sources of NO
synthesis during the CAM induction by ABA were also analyzed. The results showed that the rates of NO emission and cellular NO content
increased markedly during the ABA-induced C3-CAM transition in pineapple. Moreover, the NO removal from ABA-treated tissues with NO
scavengers completely blocked the CAM induction, indicating that NO acts as a downstream signal in this signalling event. Similarly, the
inhibition of NR activity abolished the foliar NO generation and prevented the CAM induction in response to ABA, suggesting that the ABAinduced NO synthesis is mediated by NR. Conversely, inhibitors of NOS activity did not affect the NO production in ABA-treated plants.
Altogether, the results indicate that NO is a key component in the ABA signalling cascade that triggers the CAM induction in pineapple and
that NR seems to be the main enzymatic source of NO during this signalling event. Supported by FAPESP.
(a) Department of Botany, University of Sao Paulo
P09007 Lipid-soluble antioxidants protect chloroplast DNA from damage due to photooxidative stress
Mayle, Ryan-presenter [email protected](a)
Li, Zhirong (b)
Niyogi, Krishna K (b)
Sears, Barbara B (a)
Although photosynthesis is essential for harvesting the sun‘s energy, reactive oxygen species (ROS) are generated at three different sites in
the chloroplast thylakoid membrane: photosystems I and II, as well as the light-harvesting complex of PSII. Because ROS can chemically
alter proteins, lipids, and nucleic acids, processes exist to rapidly divert or detoxify ROS within the chloroplast. Lipid-soluble antioxidants and
nonphotochemical quenching have been shown to protect the integrity of the photosynthetic apparatus, but it is unknown if they protect
chloroplast DNA (cpDNA). This report describes a genetic assessment of DNA damage due to ROS by comparing cpDNA mutation rates of
two Chlamydomonas lines grown under various light conditions. One cell line is a light-sensitive double mutant, npq1 lor1, which is deficient
in specific antioxidants (zeaxanthin and lutein) and in non-photochemical quenching. It is expected that this line will accumulate more
chloroplast mutations than do wild-type cells. In the other cell line, transgene expression results in higher levels of the antioxidant
tocopherol within the chloroplast. If ROS from the photosynthetic apparatus are the primary cause of mutations in the light-sensitive cells,
tocopherol might act to reduce the mutation rate by quenching some ROS and preventing lipid peroxidation chain reactions in the thylakoid
membrane. Chloroplast DNA mutation rates are being assessed by identifying mutations to spectinomycin resistance, isolating DNA from the
new mutants and characterizing changes in the sequence of the 16S rRNA gene. Initial results suggest that the light-sensitive line has a
significantly higher mutation rate than do wild-type cells, and that higher tocopherol levels lower the mutation rate only slightly.
(a) Michigan State University (b) University of California, Berkeley
P09008 Differential reactive oxygen species production and root hairs deformations in soybean-Bradyrhizobium interaction
under saline and osmotic stress
Munoz, Nacira B (a)
Melchiorre, Mariana N (a)
Racca, Roberto W (a)
Lascano, Hernan R-presenter
[email protected](a)
The rhizobia-legumes symbiotic interaction induces several biochemical, genetics and morphological changes in root hairs. The tightly
controlled reactive oxygen species (ROS) levels have a key role in all nodulation steps. Salinity and drought modified the ROS levels and
strongly reduce the nodulation process. Root hair curling is an early and essential step in the symbiotic interaction. In this work, ROS
production and curling responses were analyzed in soybean young root hairs in presence of Bradyrhizobium japonicus under saline (50, 100,
150 mM NaCl) and osmotic (100, 200 and 300 mM sorbitol) stress. ROS levels and root hairs deformations were determined by microscopy
using non fluorescent and fluorescent dyes The intracellular and apoplastic ROS production, were higher in inoculated root hairs than in non
inoculated ones since 2 min after inoculation. ROS production in root hairs was completely abolished by saline treatment, in both inoculated
and non-inoculated roots, while osmotic treatments notably increased it. Likewise, root hairs deformations were inhibited under saline
treatment, but not under osmotic ones. These differential early effects determined late symbiosis events such as nodule development. The
presence of calcium chelator, plasma membrane calcium channel inhibitors, NADPH oxidase inhibitor and superoxide radical scavengers
diminished both ROS levels and root hair deformations. Ours results suggest that saline and osmotic stress have differential effects on early
ROS generation that differentially influence early symbiosis events like root hair deformation. Saline stress inhibited both ROS generation
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and root hair deformation in a way which could involve calcium metabolism impairment.
(a) Instituto de Fitopatologia y Fisiologia Vegetal (IFFIVE-INTA). Area de Fisiologia Vegetal
Session P10 – Abiotic Stress
P10001 SLAC1 is required for plant guard cell S-type anion channel function in stomatal signalling
Wang, Yong-Fei-presenter [email protected](a,b)
Triin , Vahisalu (a,c)
Julian , Schroeder (b)
Jaakko , Kangasjarvi
(c)
Hannes , Kollist (a,c)
Noriyuki , Nishimura (b)
Wai-Yin , Chan (b)
Gabriel , Valerio (b)
Airi , Lamminmaki (c)
Mikael ,
Brosche (c)
Heino , Moldau (d)
Radhika , Desikan (e,f)
Stomatal pores, formed by two surrounding guard cells in the epidermis of plant leaves, allow gas exchange in leaves and control
transpirational water loss to the atmosphere. Stomata restrict the entry of ozone - the major air pollutant with increasingly negative impact
on crop yields. The aperture of stomatal pores is regulated by transport of osmotically active ions and metabolites across guard cell
membranes. Despite the vital role of guard cells in controlling plant water loss and ozone sensitivity, genes encoding some of the major
regulators of stomatal movements remain unknown. Guard cell anion channels have been proposed to function as important regulators of
stomatal closure and to be essential in mediating stomatal responses to physiological and stress stimuli. However, genes encoding
membrane proteins mediating guard cell anion efflux have not been identified to date. Here we report the mapping and characterization of
an ozone sensitive Arabidopsis mutant, slac1. We show that SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1) is preferentially expressed in
guard cells and encodes a distant homolog of fungal and bacterial dicarboxylate/malic acid transport proteins with 10 predicted
transmembrane domains. SLAC1 is essential for stomatal closure in response to ABA, ozone, light/dark transitions, humidity change, Ca2+,
H2O2, and NO. Mutations in SLAC1 abolish cytosolic Ca2+- and ABA-activated slow (S-type) anion channel currents, but do not affect rapid
(R-type) anion channel or ABA-activated Ca2+ channels. A low homology of SLAC1 to bacterial and fungal malate transporters and the
disruption of S-type malate-permeable anion channels in slac1 mutants suggest a vital role for the plasma membrane protein SLAC1 in the
function of S-type anion channels.
(a) Co-first authors (b) Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla,
CA 92093-0116, USA. (c) Plant Biology, Department of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki,
Finland. (d) Institute of Technology, University of Tartu, Tartu 50411, Estonia. (e) Centre for Research in Plant Science, University of the
West of England, Bristol, UK. (f) Current address: Division of Biology, Imperial College London SW7 2AZ, UK.
P10002 Leaf Fatty Acid and Amino Acid Compositions in Wheat Lines with Rigid Pubescence
Aytasheva, Zaure G.-presenter [email protected](a,b)
Rysbekova, Aiman B. (a,b)
Polimbetova, Fatima A. (b)
Bogdanova, Elizaveta
D. (b)
http://www.kazsu.kz
Rigid hair cells are characterized by elongated nuclei with maximal nuclear area at the stage of seedlings. At this period the nuclei are
localized in distal part of the trichome in contrast to those of soft hair cells which are visible as rounded particles in basal part of the stretch.
These differences may occur necessary for a specific cell mobilization towards accelerated leaf morphogenesis, nuclear-cytoplasmic
exchange and plant defence reactions to stress at early ontogenetic stages. Protective leaf response in case of rigid pubescence may be
gained due to the accumulation of unsaturated fatty acids, and namely linolenic acid (LA, C18:3). Its moiety has shown a 20% greater
content in comparison to LA content in softly pubescent leaves. Amino acid profiles have been determined for the leaves of hairless, softly
pubescent and rigidly pubescent wheat cvs and lines. It is suggested that reduced tyrosinylation (decreasing Tyr/Phe ration) in the leaves
with rigid hair cells during the passage from seedlings to the stage of anthesis hinders from protein, and specifically membrane protein
hydrophilization, thereby preventing from proteins instability. Based on the presence of as ―accumulational‖, and ―expense-dependent‖
metabolic profiles for the spectra of fatty acids and amino acids in rigidly pubescent leaves throughout ontogenesis, rather various than a
single scheme is considered to be imposed on rigid trichome functioning under stress conditions.
(a) al-Farabi Kazakh National University (b) Institute of Plant Biology and Biotechnology
P10003 The physiological and molecular study of rapeseed responses to abiotic stresses
Jeong, Yu Jeong (a)
Choy, Yoon Hi (a)
Hwang, Ji Hye (a)
Joo, Hye Joon (a)
Byun, Yoon Jeong (a)
Lee, Dong Hee (a)
Lee,
June Seung-presenter [email protected](a)
Oilseed rape is now the second largest oilseed crop in the world. Recent weather condition is also decreased the rapeseed productivity as
well as in other crops. So, we investigated the effect of various stresses such as drought, flooding and cold responses in rapeseed varieties,
Youngsan, Tammi, Nahan (Spring type), Yudal (Winter type), and Sandongchae (the Korea native rapeseed). The survival rate of
Sandongchae and Naehan were significantly higher than in other varities during the drought and cold stress. Nahan was also showed the
highest of survival rate under flooding stress, but highly decrease of seed germination after normal seed storage condition (4-6 degree) for
1 year. To study the cold stress related molecular mechanism in rapeseed, we analyzed the gene expression profiles from cold stress
treated rapeseed leaves using 1.6K cold specialized Arabidopsis cDNA chip. According to the hierarchical clustering pattern among the
rapessed 5 varities, it was revealed that the survival results of previous freezing test was well consistent with the gene expression pattern
during cold stress.
(a) EWHA Womans University
P10005 Methionine Sulfoxide Reductase Regulates ABA-mediated Salt Stress Tolerance
Lee, Jent turn-presenter [email protected](a,b)
Chan, Ming Tsair (a)
Many plant genes can respond to various stresses for plant adaptation to environmental change. To identify the function of drought- and/or
salt-stress tolerant candidate genes, we used T-DNA activation tagging to isolate a water deficit-tolerant (wdt1) mutant under water-deficit
stress. wdt1 also enhances tolerance to salt stress. T-DNA inserted between two methionine sulfoxide reductases, MsrB5 and MsrB6,
activated the expression of both genes in wdt1. Overexpression of MsrB5 (B5OX) or MsrB5 plus MsrB6 (B5+6OX) but not MsrB6 alone
confers tolerance to salt stress. wdt1, transgenic B5OX and B5+6OX plants accumulate more proline under salt stress than the wild type or
MsrB5 and MsrB6 knock-out lines. Seed germination of wdt1, B5OX and B5+6OX is sensitive to exogenously applied ABA, and increased
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ABA content is found in transgenic wdt1, B5OX and B5+6OX under salt stress. The mRNA transcripts of ABA synthesis gene, AAO3, were
highly induced in wdt1, B5OX and B5+6OX under salt stress. Downstream ABA-responsive genes are activated in B5OX and B5+6OX under
salt stress. Thus, MsrB5 protects the plant cell under salt stress by participating in an ABA-mediated salt-tolerance mechanism.
(a) Agricultural Biotechnology Research Center, Taipei, Taiwan (b) National Defense Medical Center, Taipei, Taiwan
P10006 Til1, a Temperature-Induced Lipocalin, Is Essential for Basal and Acquired Thermotolerance in Arabidopsis
Chi, Wen-tzu (a)
Liu, Hsiang-chin (a)
Charng, Yee-yung-presenter [email protected](a)
Lipocalins are a group of widely distributed proteins that can be found in bacteria, invertebrates, vertebrates, and plants. Members of this
protein family often share low identity in amino acid sequence. Classification of lipocalin is based on the following common feature: the
presence of sequence conserved region (SCR) in the primary structure and an eight-stranded antiparallel β-sheet that forms a β-barrel. The
plant temperature-induced lipocalin (Til) genes have been shown to be responsive to extreme temperature stress, but its biological function
was not clear. In Arabidopsis genome, only one copy of Til can be found, while in monocots two homologues (Til1 and Til2) are present.
The Arabidopsis lipocalin is more similar to the heat-inducible Til1 of wheat in amino acid sequence and hence was named as AtTil1 here.
An Arabidopsis homozygous T-DNA insertion line of AtTil1 (til1-1) was isolated and subjected to reverse genetic analysis. Western blot
analysis with a specific antibody showed that til1-1 was a null mutant. The til1-1 seedlings displayed defects in basal and acquired
thermotolerance. Introducing a wild-type copy of AtTil1 gene into til1-1 complemented the mutant phenotype. Over-expression of AtTil1 in
the wild-type plant increased the basal level of Til1 protein, but no enhancement of basal thermotolerance was observed. Unlike the Hsa32
and Hsp101 knockout mutants, til1-1 did not show significant difference in hypocotyls elongation after heat treatment as compared to the
wild type. This is the first report indicating that lipocalin is involved in thermotolerance.
(a) Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, ROC
P10007 Conserved and Novel microRNAs in the legume Phaseolus vulgaris in response to ABA and drought
Reyes, Jose L-presenter [email protected](a)
Arenas, Catalina (a)
Perez, Beatriz (a)
Rabanal, Fernando (a)
Estrada, Georgina
(a)
Sanchez, Federico (a)
Covarrubias, Alejandra (a)
In plants, drought stress produces several physiological and cellular changes, with abscisic acid (ABA) signaling playing a central role in
mediating the corresponding responses. Phaseolus vulgaris (common bean) represents an important crop in Mexico, and it provides a
unique model for the analysis of different adaptation strategies. We are exploring the participation of microRNAs in the regulation of
processes related to perception/adaptation to drought stress and other external stimuli. To address this question, we have constructed
cDNA libraries to identify small RNAs present under optimal conditions, water stress conditions or after ABA treatment. To date, we have
found microRNAs conserved in Arabidopsis and other species as well as sequences representing potential microRNAs. We will present the
characterization of novel microRNAs we have found as specific to the legume lineage and their relationship to stress responses. In addition,
we will show the development of experimental tools to study microRNAs in this and other model legumes such as Medicago truncatula or
Lotus japonicus.
(a) Instituto de Biotecnologia-UNAM
P10008 Reexamining the role of superoxide dismutase in photosynthesis: plants without SOD activity in the chloroplast
and cytosol
Cohu, Christopher M.-presenter [email protected](a)
Abdel-Ghany, Salah E. (a)
Reynolds, Kathryn A. (a)
Pilon , Marinus
(a)
The regulation and biological role of stromal superoxide dismutases has mainly been studied in the context of abiotic stress. However,
recent studies indicate that the availability of Cu is the primary regulator of cytosolic (CSD1) and stromal (CSD2) SOD activity and not stress
(Cohu and Pilon 2007; Yamasaki et al., 2007). During sufficient Cu supply, CSD1 and CSD2 are expressed and active, yet during Culimitation these Cu/ZnSODs are down-regulated while stromal FeSOD is up-regulated. During Cu-limitation, Plastocyanin levels remain high,
suggesting that the delivery of Cu to Plastocyanin is a priority. Plants contain the Cu chaperone for SOD (CCS) that delivers Cu to both CSD1
and CSD2, and in Arabidopsis is encoded by one gene that encodes both cytosolic and plastidic proteins (Abdel-Ghany et al., 2005; Chu et
al., 2005). We investigated a knock-out of CCS with no detectable Cu/ZnSOD activity. When the CCS-KO is grown with sufficient Cu these
plants also lack FeSOD activity. These CCS-KO plants without measurable stromal or cytosolic SOD activity do not exhibit a visual
phenotype, and chlorophyll fluorescence measurements do not indicate reduced photosynthetic rates compared to wild-type, even under
high light stress. Thus Cu/ZnSOD and FeSOD activities are not essential under the laboratory growth conditions imposed. The data suggest
a reconsideration of SOD function; Cu/ZnSOD could play a more important role in metal homeostasis than in oxidative stress reduction.
References cited: Abdel-Ghany et al., (2005) FEBS Letters, 579, 2307-2312; Chu et al., (2005) Plant Physiology 139: 425-436; Cohu and
Pilon (2007) Physiologia Plantarum, 129, 747-755; Yamasaki et al., (2007) Journal of Biological Chemistry 282:16369-78163.
(a) Colorado State University
P10009 Mineral Ions Uptake Responses And Antioxidant Enzyme Activities Of Cultivated Barley Under Saline Stress
Kook, Hee Sun-presenter [email protected](a)
Park, Tae Il (b)
Yun, Song Joong (a)
Saline environments adversely affect plant growth by the toxic effects of salts absorbed by plants. In the previous experiment, we selected
several tolerant cultivars and landraces from over 1,000 barley germplasms which were screened in a high salt (0.4%,w/w) reclaimed soil.
This study was conducted to elucidate salt tolerance mechanism of a collection from Tunisia (Tunisia 76; T76) at the germination and early
seedling stages. Gwandongpi 41 (G41) was used as a susceptible control variety. Germination was examined in a culture solution containing
0, 150, 300, and 450 mM NaCl, respectively. Mineral content and antioxidant enzyme activity were analyzed for the two-week-old seedlings
grown in 0 or 200 mM NaCl for 0, 1, 3, and 5 days, respectively. Both varieties showed drastic differences in germination and early growth
in saline conditions. T76 showed over 97% germination while G41 only 7% at 300 mM NaCl. The germination and seedling growth
responses were highly related to sodium ion contents in the shoots. Sodium ion content was about three times higher in G41 than in T76 in
the shoot of the seedlings treated for 5 days at 200 mM NaCl. The K+/Na+ ratio, which was mostly affected by sodium content, was
significantly higher in T76 than in G41. These results indicate that higher salt tolerance in T76 is conferred at least in part by the avoidance
of salt accumulation in the shoot at high salt conditions. Further investigation on the activities and isoform profiles of barley antioxidant
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enzymes (SOD, CAT, APX, POX, and GR) is on the way.
(a) Division of Agriculture life Sciences, Chonbuk National University (b) Honam Agricultural Reserch institute
P10010 Arabidopsis methionine sulfoxide reductase B gene is a non-antibiotic selection marker for plant transformation
Shu-Hong, Lee-presenter [email protected](a)
Pei-Shan, Chien (a)
Jent-Turn, Lee (a)
Ming-Tsair, Chan (a)
Selectable marker genes are required for the efficient transformation of transgenic plants. But the persistence of selectable marker genes
and antibiotic selection agent caused public concerns of environmental safety and human health issues are undesirable. Therefore, we want
to develop a novel and efficient plant native non-antibiotic selection system for the selection of transgenic plants. In this system, we take
advantage of MsrB7 as a selection marker gene which belongs to methionine sulfoxide reductase B (MsrB) family protein. The basic concept
is that proteins are easily damaged by reactive oxygen species (ROS), with Met being one of the amino acid residues most susceptible to
oxidation. Methionine oxidation to methionine sulfoxide (MetSO), which results in modification of activity and conformation for many
proteins, is reversed by MSR protein. Therefore, we use non-antibiotic agent such as methyl viologen, which can increase ROS accumulation
in plant cells, to be a selection agent and conduct the selection in transgenic plants with MsrB7. In our results, transgenic plants are
successfully selected in 1/2 MS with 300 nM methyl viologen. During methyl viologen selection process, we can distinguish the putative
transgenic and non-transgenic plants easily. Meanwhile, from the results of Southern and northern bolt analysis, we do obtain the real
transgenic plants by this novel selection system. Taken together, the MsrB7 system provides a novel selection system distinct from
conventional antibiotic selection system.
(a) Agricultural Biotechnology Research Center, Academia Sinica
P10011 Calcium-dependent regulation of abiotic stress responses by alternative complex formation of specific CIPK-type
protein kinases with distinct CBL calcium sensors proteins
Waadt, Rainer (a)
Batistic, Oliver (a)
Knutova, Iuliia (a)
Kudla, Joerg-presenter [email protected](a)
Intracellular releases of calcium ions belong to the earliest events in signal perception by plant cells. Calcineurin B-like proteins (CBLs)
represent a group of calcium sensor proteins likely to function in deciphering calcium signals. CBLs interact with a group of serine/threonine
protein kinases designated as CBL-interacting protein kinases (CIPKs). In Arabidopsis, 10 CBL-type calcium sensor proteins form an
interaction network with 25 CIPKs. Preferential complex formation of individual CBLs with defined subsets of CIPKs appears to be one of the
mechanisms generating the temporal and spatial specificity of calcium signals in plant cells. Reverse genetics approaches have begun to
unravel the function of several members of both protein families. We will present results of our characterization of cbl and cipk loss-offunction mutants and of our investigation of the sub-cellular localization of all CBLs from Arabidopsis. These studies suggest that CBL/CIPK
complexes function predominantly at cellular membranes and can decode Ca2+ signals in different compartments. In this context, dual lipid
modification by myristoylation and palmitoylation appears to play an important role in determining the membrane targeting of CBL/CIPK
complexes. Our reverse genetics analyses indicate that alternative complex formation of CIPK-type kinases with different CBLs enables the
simultaneous regulation of ion transport processes in different compartments of the plant cell. In this way, CBL/CIPK complexes contribute
to regulating the extrusion of Na+ ions in root tissues and in addition regulate the sequestration of Na+ into the vacuole in green tissues.
(a) Universitaet Muenster, Institut fuer Botanik
P10012 ESSENTIAL ROLE OF MYB TRANSCRIPTION FACTOR: PvPHR1 IN PHOSPHATE STARVATION SIGNALING IN
COMMON BEAN (Phaseolus vulgaris)
Hernandez, Georgina-presenter [email protected](a)
Valdes-Lopez, Oswaldo (a)
Ramirez, Mario (a)
Lara, Miguel (a)
Vance,
Carroll P. (b)
Girard, Lourdes (a)
Sanchez, Federico (c)
Reyes, Jose L. (c)
Phosphorus (P), an essential element for plants, is one of the most limiting nutrients for plant growth. In Arabidopsis, several responses to P
starvation (-P) are regulated at the level of transcription, involving transcription factors (TF) such as: PHR1, WRKY75, ZAT6 and BHLH.
Despite the agronomic importance of legumes, little is known about their regulation of -P responses. Crop production of common bean
(Phaseolus vulgaris), the most important legume for human consumption, is often limited by low P in the soil. In order to study P starvation
signaling in beans, expression of MYB TF genes that were induced in -P bean roots was analyzed in detail. In particular we analyzed MYB TF
TC2883 (PvPHR1), which was induced 2-fold and showed 63% identity to the Arabidopsis PHR1 gene. In order to investigate the possible
role of PvPHR1, a RNAi approach was used to down-regulate this gene in composite bean plants. Target genes transcription analysis in -P
composite bean plants indicated that PvPHR1 TF is an essential positive regulator for P acquisition, homeostasis and transport genes but not
for phytohormone-metabolism genes involved in modification of root architecture. We identified bean genes homologous to Arabidopsis At4
(CV536419) and PHO2 (TC1095) that participate in the PHR1-mediated signal transduction pathway. In addition, a micro RNA homologous
to Arabidopsis miR399 was cloned from beans. We showed, for the first time in a legume plant, that PvmiR399 transcription by PvPHR1
increases in -P bean plants. The analysis of P-deficient DCL1-silenced composite bean plants, that showed reduced PvmiR399 levels, lead us
to conclude that PvmiR399 negatively modulates the regulation of PvPHO2 of -P target genes. A model for PHR1-mediated signaling
pathway in beans is proposed.
(a) Center for Genomic Sciences-National University of Mexico (UNAM) (b) University of Minnesota / USDA (c) Institute for BiotechnologyNational University of Mexico
P10013 Improvement of drought tolerance and grain yield in common bean by overexpressing trehalose-6-phosphate
synthase in rhizobia
Iturriaga, Gabriel-presenter [email protected](a)
Suarez, Ramon (a)
Wong, Arnoldo (a)
Ramirez , Mario (b)
Barraza, Aaron
(a)
Orozco, Maria del Carmen (a)
Cevallos, Miguel A (b)
Lara, Miguel (b)
Hernandez, Georgina (b)
Environmental conditions are severe limiting factors for growth and yield in crops. Osmotic adjustment and accumulation of compatible
solutes is a common response present in many microorganisms and plants. Trehalose, one of the most effective osmoprotectants, is a nonreducing disaccharide that occurs in many organisms including the symbiotic bacteria Rhizobium. Here we show the effects of
overexpressing trehalose-6-phosphate synthase in free-living Rhizobium etli and in symbiosis with Phaseolus vulgaris (common beans)
plants. Black bean plants inoculated with R. etli overexpresing trehalose-6-phosphate synthase gene had more nodules with increased
nitrogenase activity and higher biomass compared to plants inoculated with wild type R. etli, whereas plants inoculated with a R. etli mutant
in trehalose-6-phosphate synthase gene had fewer number of nodules and less nitrogenase activity and biomass. Three-week-old plants
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subjected to drought stress fully recovered whereas plants inoculated with wild type or mutant strain wilted and died. The yield of bean
plants inoculated with R. etli overexpressing trehalose-6-phosphate synthase gene, and grown upon constant irrigation increased more than
50%. Macroarray analysis of 7200 ESTs from nodules of plants inoculated with the strain overexpressing trehalose-6-phosphate synthase
gene revealed up-regulation of genes involved in stress tolerance, carbon and nitrogen metabolism, suggesting a signaling mechanism for
trehalose. Thus, trehalose metabolism in rhizobia is key for signaling plant growth, yield and adaptation to abiotic stress.
(a) Centro de Investigacion en Biotecnologia-UAEM (b) Centro de Ciencias Genomicas-UNAM
P10014 Aluminium induces changes in organic acids metabolism in Coffea arabica suspension cells with differential Al
tolerance
Ramirez Benitez, Jose E-presenter [email protected](a)
Hernandez Sotomayor, Teresa (a)
The primary Al tolerance mechanism in plants involves exudation and/or accumulation of specific organic acid species, which form nonphytotoxic complexes with Al3+ under physiological conditions. An evaluation was done of the role of organic acids in the tolerance
mechanism of a cell suspension line of coffee (Coffea arabica L.) that exhibits Al tolerance (LAMt) but for which the metabolic tolerance
mechanism remains unknown. Significant differences existed in malate dehydrogenase and citrate synthase activities (key enzymes in
organic acids metabolism) between protein extracts (day 7 of culture cycle) of the L2 (Al-sensitive) and LAMt (Al-tolerant) cells when cell
suspensions were treated with 100 μM AlCl3 . HPLC analysis showed that the suspension cells of both lines exudate malate when incubated
in a minimal solution but that exudation was not enhanced by treatment with AlCl3 (100 μM). This is the first study demonstrating that
plant Al tolerance may be associated with down-regulation of malate dehydrogenase and citrate synthase activities. This research was
supported by the Consejo Nacional de Ciencia y Tecnologia (CONACyT project No C45798-Z) and fellowships granted JERB by the CONACyT
(176793) and the Sistema Nacional de Investigadores (grant No 4422)
(a) Unidad de Bioquimica y Biologia Molecular de Plantas, Centro de Investigacion Cientifica de Yucatan
P10015 Overexpression of Rhododendron catawbiense plasma membrane intrinsic proteins (RcPIPs) lowers constitutive
freezing tolerance and cold acclimation ability of transgenic Arabidopsis plants
Peng, Yanhui (a)
Arora, Rajeev-presenter [email protected](a)
Under freezing conditions, plant cells typically experience dehydration because of extracellular ice and consequent ex-osmosis due to
disequilibrated chemical potential between cellular water and extracellular ice. This water-efflux might be under regulatory control of
aquaporins (AQPs). In a seasonal cold acclimation (CA) study of Rhododendron catawbiense, we noted that two AQPs, RcPIP2-1 and
RcPIP2-2, were significantly down-regulated from August thru February as the leaf freeze-tolerance (FT) increased from -7 C to -50 C. We
hypothesized this down-regulation to be one of the components of CA process that prepares cells to resist freeze-desiccation. To test this
hypothesis we overexpressed RcPIP2s in Arabidopsis and compared their FT with WT controls. Our data indicated a significantly lower
constitutive FT of RcPIP2-OXP plants compared to WT controls. Moreover, after a CA treatment, the RcPIP2s-OXP plants were significantly
less freeze-tolerant than WT plants. Lower CA ability of RcPIP2-OXP plants supports our hypothesis and may, presumably, be due to their
reduced ability to resist cellular dehydration during extracellular freezing, a notion supported by dehydration-rehydration kinetics data which
suggests that RcPIP2-OXP plants, indeed, dehydrate at much faster rate than WT controls. Our phenotypic and microscopic observations
indicated bigger leaf-size and larger mesophyll cells of RcPIP2-OXP plants than WT controls. We propose that lower constitutive FT (i.e.
greater freeze-thaw injury) of RcPIP2-OXP plants may be due to relatively smaller specific cell surface [surface-to-volume (S/V) ratio] and
consequently their propensity to greater mechanical stress during freeze-thaw (i.e. greater volume strain per unit surface during cell
contraction or expansion).
(a) Iowa State University
P10016 Determining the molecular mechanisms of temperature modulation of defense responses in arabidopsis thaliana
through int mutants
Hipps, Ashley N-presenter [email protected](a)
Zhu, Ying (a)
Hua, Jian (a)
Defense responses are modulated by temperature, and often an increased temperature suppresses disease resistance in plants. Studying
such a regulation is critical not only for understanding biotic and abiotic adaptive responses in plants, but also for designing strategies to
cope with global climate changes. We are taking a genetic approach to reveal the molecular mechanisms underlying the suppression of
defense by increased temperature. The SNC1 gene is a NB-LRR type of disease resistant (R) gene, and its gain-of-function mutant snc1-1
leads to constitutive defense responses and consequently a dwarf phenotype at a normal growth temperature of 22 degrees Celsius, but not
at a high temperature of 28 degrees Celsius where defense responses are inhibited. Using the morphological phenotype as a readout of
defense responses, we carried out a genetic screen in snc1-1 for mutants insensitive to temperature modulation, naming them int. Three
different int mutants; int 28, int 103, and int 162, show dwarf phenotype at both normal and high temperatures in a snc1-1 dependent
manner. Using map-based cloning, we found that INT 28 and INT 162 are located on chromosome 1 while INT 103 is on chromosome 5.
Fine mapping will refine the location of each int mutation, and candidate genes will be sequenced to identify the causal mutations. We
expect that the cloning of these genes will enhance our understanding of interplay between temperature responses and defense responses.
(a) Cornell University
P10017 Iron Deficiency in Arabidopsis Roots: High-resolution Transcriptional Profiling to Decipher Regulatory Networks
Long, Terri A-presenter [email protected](a)
Wang, Jean (a)
Burrill, Joel (a)
Benfey, Philip (a)
Anemia caused by iron deficiency is one of the most common and widespread nutritional disorders in the world. Plants, the main source of
dietary iron in many parts of the world, undergo a host of developmental, biochemical and genetic alterations in response to iron deficiency
(-Fe). Using a systems approach, we are characterizing the spatio-temporal expression of genes within Arabidopsis thaliana roots. Our
results showed that hundreds of genes are transcriptionally activated or repressed within 24 hours of -Fe, at specific longitudinal and radial
zones within plant roots. Clustering analysis reveals that many co-regulated genes belong to specific Gene Ontology categories and are
associated with cis regulatory elements. From the list of affected genes we identified two potentially regulatory genes with unknown
functions whose T-DNA insertion lines showed alterations in response to -Fe. We are currently elucidating downstream targets of these
proteins to begin to build a gene regulatory network for initialization of the -Fe response. This study will allow us to better understand the
correlations between transcriptional alterations and developmental and biochemical responses, and to determine how regulatory networks
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control -Fe, and are controlled by, -Fe
(a) Duke University
P10018 Identification of two small RNAs from Phaseolus vulgaris present under low-water availability conditions
Arenas, Catalina-presenter [email protected](a)
Reyes, Jose L (a)
Covarrubias, Alejandra (a)
In plants, drought stress produces a general inhibition of growth. The study of the mechanisms of regulation of gene expression in this
adverse condition is essential for the understanding of the plants response to water limiting environments. We are interested in identifying
the different processes in which miRNAs participate as regulatory molecules, and involved in signal perception and/or transduction.
Phaseolus vulgaris (common bean) represents an important crop in Mexico, and it provides an interesting model for exploring different
adaptation strategies. Because of this, and since the bean genome sequence is not fully known yet, we have started to develop tools to
identify and characterize those miRNAs implicated in common bean stress responses. We have isolated small RNAs present under optimal
irrigation, water stress conditions and ABA treatment to construct cDNA libraries and identify novel miRNAs. Currently, we are studying two
novel small RNAs. They are not present in Arabidopsis thaliana and are specific to legumes. One of them is a miRNA and seems to be
involved in embryogenesis processes. We suggest that the second small RNA could be involved in drought stress responses. We will present
the characterization of these small RNAs and our initial attempts to explore the role of small RNAs in the mechanisms of adaptation relevant
to legume physiology.
(a) Instituto de Biotecnologia, UNAM
P10019 The long-term effects of drought and high temperature on N metabolism in a C 3 grass
Bernard, Stephanie M.-presenter [email protected](a)
StClair, Sam B. (b)
Sudderth, Erika A. (b)
Torn, Margaret S. (a)
Ackerly,
David D. (b)
Andersen, Gary L. (a)
http://www-esd.lbl.gov/ECO/MME/index.htm
Increased temperature and fluctuation of soil water content are likely to affect the availability and demand of nitrogen. Nitrogen (N) is often
the major nutrient limiting plant productivity in many terrestrial ecosystems. Aspects of the regulation of the major pathways of N
assimilation from root uptake to assimilation in organic compounds have been elucidated in response to drought stress. However, further
studies are necessary to understand the response of N metabolism to the long-term effects of mild abiotic stress, which will be relevant to
our understanding of ecosystem response to global climate change. In three greenhouses experiments, we have studied the impact of
precipitation regime (low, ambient and high rainfall), N availability (addition of inorganic N) and increased temperature (+4oC), on an
annual C3 grass, Avena barbata , typical of Californian grasslands. Leaf and root samples from A. barbata were collected during two
growing seasons and used in a series of analyses including gene expression, enzyme activity and leaf level photosynthesis. We studied
transcript abundance of key genes of carbon and nitrogen metabolism (rubisco, glutamine synthetase 1 and 2, nitrate reductase). Our
results suggest long-term changes in water availability significantly affect RbcS, GS1 and Nia transcripts abundance, with the effect
dependent on soil N content. We also show that plant response to high temperature depends on water availability. To broaden our genomic
study, four cDNA libraries from the roots and leaves of plants grown under ambient and high precipitation regimes were sequenced at the
Joint Genome Institute. Comparative analysis of the cDNA libraries will be discussed.
(a) Earth Sciences Division, Lawrence Berkeley National Laboratory (b) Department of Integrative Biology, UC Berkeley
P10020 Post-translational modfications of Arabidopsis Receptor for Activated C Kinase 1 (RACK1) scaffold proteins
regulate physiological responses to environmental stresses
Ullah, Hemayet-presenter [email protected](a)
Dozier, Uvetta (a)
Kundu, Nabanita (a)
Fennell, Herman (a)
Plants encounter a combination of environmental stress conditions simultaneously and to response, they often utilize overlapping signaling
pathways. In this regard, scaffold proteins are uniquely poised to integrate signals from multiple pathways by bringing interacting signaling
components to proximity. Scaffold protein RACK1 in metazoan mediates diverse signaling pathways and is reported to interact with more
than 80 diverse proteins. Loss-of-function alleles of three rack1 genes in Arabidopsis implicate the proteins in diverse environmental stress
signaling pathways. The proteins can potentially dimerize and higher levels of homo/hetrodimerization were observed under water stress
conditions. Non-reducing SDS-PAGE studies identified disulfide bonds as responsible for the dimerization of RACK1 proteins during water
stress condition. Molecular structural studies identified two solvent exposed potential tyrosine phosphorylation (Y230 and Y248) and two
sumoylation sites (K272 and K276)on RACK1A protein. In mammalian studies, tyrosine phosphorylations were attributed to increase affinity
of RACK1 protein to its binding partners. Site-directed mutagenesis studies in the potential tyrosine phosphorylation sites and sumoylation
sites reveal functional role of these sites in water stress response. Split-ubiquitin based cDNA library screen identified 10 putative RACK1
interacting clones from diverse stress pathways. In addition, identification of four ribosomal proteins as potential RACK1 interactors
correlates with the ribosomal localization of RACK1 proteins. It is proposed that by virtue of homo/ heterodimerization and/or posttranscriptional modification based interaction with diverse proteins, Arabidopsis RACK1 regulate diverse environmental stress signaling
pathways.
(a) Howard University, Dept. of Biology
P10021 Role of a Cell Wall Associated Kinase in Arabidopsis Mineral Responses
Johnson, Janelle-presenter [email protected](a)
Sayre, Tobias (a)
Leung, Wai-Hin (a)
Tong, Hongyun (a)
He, Zheng-Hui (a)
The cell wall-associated receptor kinase (WAK) and WAK-like (WAKL) gene family members are good candidates for signaling molecules that
physically link and communicate between the cell wall and the cytoplasmic compartment. Genetic and molecular studies have shown that
WAK/WAKL members play important roles in a wide range of functions, including cell elongation, plant development, bacterial pathogenesis,
and abiotic mineral and heavy metal responses. WAKL4, a member of the WAK/WAKL family, was shown to play a functional role in mineral
responses. Previous studies have shown that WAKL4 promoter impairment resulted in hypersensitivity to K+, Na+, Cu2+ and Zn2, and
WAKL4 was required for the up-regulations of zinc transporter genes during zinc deficiency. In combination with bioinformatic analyses,
transgenic studies have located regions in the WAKL4 promoter with putative mineral-responsive cis-elements. Transgenic lines carrying
constructs of serially deleted WAKL4 promoters fused to beta-glucuronidase reporter gene have been generated. Reporter gene assays in
different tissues under different mineral conditions were performed. Yeast two-hybrid screenings have identified putative proteins that
interact with the WAKL4 kinase. The functional roles for these proteins are being analyzed genetically and biochemically. Our goal is to fully
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characterize the mineral-responsive cis-acting elements in the WAKL4 promoter and to eventually elucidate WAKL4-mediated mineral
signaling pathways.
(a) San Francisco State University
P10022 Elucidation of the acclimation response of Arabidopsis seedlings to low oxygen stress from the cellular to wholeplant level
Mustroph, Angelika (a)
Oosumi, Teruko (a)
Branco-Price, Cristina (a)
Hamersky, Kayla (a,b)
Jang, Charles (a,b)
Lee, Seung
Cho (a)
Ma, Kelvin (a)
Sorensen, Reed (a)
Larive, Cynthia (a)
Bailey-Serres, Julia-presenter [email protected](a)
Arabidopsis thaliana was used to elucidate mechanisms of acclimation to low oxygen (hypoxia) stress. To evaluate the intricate response,
we established transgenic lines that express a FLAG epitope-tagged ribosomal protein (RPL18) under the control of the CaMV 35S and celltype specific promoters. These lines were used to purify polysomal mRNAs from crude cell extracts of cryo-preserved samples by
immunoprecipitation. Microarray profiling of cell-specific polysomal mRNA populations was achieved for the root apex, whole root and aerial
organs of seedlings. All organs and cell types examined induced a general response to short-term hypoxia, which included increased
translation of a core of ~100 mRNAs. Specific responses of organs and cell-types were also resolved. The 35S:FLAG-RPL18 line was used to
study the dynamic response to hypoxia (2h or 9h), as well as re-oxygenation (9h hypoxia + 1h air). Profiling of immunopurified polysomal
mRNA and 1H-NMR quantitation of metabolites uncovered a rapid and reversible reconfiguration of carbon and nitrogen metabolism that
augments anaerobic ATP production. A major energy conserving mechanism was the dramatic inhibition of translation of over 60% of the
cellular mRNAs, which was almost completely reversed within minutes of reoxygenation. Although many strongly induced transcripts were
translated during the stress, some were recruited to polysomes only upon reoxygenation. Exploration of the biological function of 50 low
oxygen-induced proteins of unknown function using T-DNA insertion and/or overexpression mutants has led to the identification of
previously uncharacterized proteins that are critical to survival of Arabidopsis of low-oxygen and/or submergence stress. (Funding: NSF
2010 IBN-0420152 and IGERT DGE 0504249).
(a) Center for Plant Cell Biology, UC Riverside (b) ChemGen IGERT Program
P10023 Improved tolerance to multiple abiotic stresses in transgenic alfalfa accumulating trehalose
Suarez, Ramon-presenter [email protected](a)
Calderon, Cecilia (a)
Iturriaga, Gabriel (a)
Trehalose is a key molecule involved in stress tolerance in anhydrobiotic organisms. Here we describe the use of a chimeric translational
fusion of yeast trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) genes to engineer stress tolerance in
alfalfa (Medicago sativa). The gene fusion was overexpressed using either the 35S promoter or the stress-regulated rd29A promoter.
Transgene insertion in the genome was checked by PCR and transcript expression by RT-PCR. Several independent transgenic plants were
selected in the presence of kanamycin and further analyzed. Trehalose was accumulated in all these lines at low levels. Moreover,
transgenic TPS1-TPS2 lines displayed a significant increase in drought, freezing, salt and heat tolerance. This is the first time that genetic
engineering of trehalose metabolism is reported in alfalfa. Moreover, these results demonstrate that engineering trehalose metabolism with
the yeast TPS fused to TPP in a chimeric bifunctional enzyme improves multiple stress protection in alfalfa. Thus, the yeast TPS-TPP gene
fusion represents a great potential for generating stress-tolerant crop plants.
(a) Centro de Investigacion en Biotecnologia-UAEM
P10024 The BNCBF overexpression and cold response proteomes of Brassica napus as determined by iTRAQ.
Savitch, Leonid V-presenter [email protected](a)
Sharpe, Andrew (a,b)
Couroux, Philippe (a)
Soleimani, Vahab (a)
Singh, Jas
(a)
The proteomes of transgenic B. napus plants overexpressing Brassica CBF/Dreb1 BNCBF5 and 17 as well as the response of B. napus to
cold stress were compared using iTRAQ (isotope tags for relative and absolute quantitation) analyses. Predicted peptide sequences were
blasted against a collection of over 400K Brassica napus ESTs generated at SRC/AAFC and PBI/NRC. A total of 1100 proteins were
identified. Changes in the levels of accumulation of over 400 proteins were detected in BNCBF5, 17 OE and the cold stressed WT. Of this,
levels of 166 proteins were affected only by cold stress and 143 proteins only by BNCBF 5 and 17 OE. Only changes in 48 proteins were
common among all three treatments. The most highly upregulated functional category of proteins are encoded by changes of up to 10
families of cor and LEA genes and suggests that direct protection of cellular constituents against the denaturative effects of dehydration is
critical. A number of proteins with altered levels of representation in BNCBF5 (20) but distinct from BNCBF17 OE (51) or vice versa support
the hypothesis that BNCBF5 and 17 transactivate different targets (Savitch et al. 2005, Zhao et al. 2006). Increased representation of a
large number of proteins (27 to 42%) encoded by genes related to transcription/translation, RNA splicing and RNA stabilization in the cold
treated WT and BNCBF5 and 17 OE suggest that increased protein synthetic capacity is required to enhance metabolic processes to develop
freezing tolerance. The comparative elucidation of the above proteomes enables the dissection of the response of the plant to cold stress
and cold acclimation to maintain metabolic capacity versus the genes required for direct protection against freezing injury.
(a) Eastern Cereal and Oilseed Research Centre, Ottawa, ON, K1A 0C6, Canada (b) Plant Biotechnology Institute, Saskatoon, SASK, S7N
0W9, Canada
P10025 ER stress sensor/transducers perceive and mitigate environmental stresses
Liu, Jian-Xiang (a)
Srivastava, Renu (a)
Howell, Stephen H-presenter [email protected](a)
http://www.gdcb.iastate.edu/faculty/facultyDetail.php?id=95
Stress tolerance is a highly desirable trait in crop plants given the demands on agriculture for supplying food, feed and fuel in the face of
greater environmental extremes. A process in plant cells that is highly sensitive to environmental conditions is the folding of proteins in the
endoplasmic reticulum. The accumulation of misfolded proteins in the ER can lead to a condition called ER stress. This form of stress is
perceived and acted upon by stress sensor/transducers located in the ER. We have identified three ER-localized bZIP transcription factors in
Arabidopsis that are candidates for ER stress sensors/transducers. They are type II proteins with a cytosol-facing bZIP domain, a
transmembrane segment, and a lumen-facing canonical site-1 protease (S1P) cleavage site. We found that one of the candidate
sensor/transducers, AtbZIP17, is activated by salt stress (Liu et al. Plant Journal 51: 897, 2007) while another, AtbZIP28, is activated in the
typical manner of an unfolded protein response (UPR) triggered by stress agents, such as tunicamycin (TM) or DTT (Liu et al., Plant Cell 19:
4111, 2007). Following different ER stresses, the transcription factors are proteolytically processed, releasing their N-terminal bZIP domains,
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which are then translocated to the nucleus. Truncated forms of these stress sensor/transducers, lacking the transmembrane segment and
lumen-facing domains, are constitutively active. When placed under the control of the 35S promoter the truncated form of AtbZIP17 causes
chronic stress and delays plant growth and development. However, when placed under the control of the RD29A stress-inducible promoter,
the construct confers salt tolerance and permits normal development under unstressed conditions. (Supported by NSF IBN0420015.)
(a) Iowa State University
P10026 Regulation of drought tolerance by the F-box protein MAX2 in Arabidopsis
Sharma, Nidhi-presenter [email protected](a)
Shen, Hui (a)
Luong, Phi (a)
Kim, Tae Houn (b)
Schroeder, Julian
(b)
Nidhi Sharma1, Hui Shen1, Phi Luong1, Tae Houn Kim2, Julian Schroeder2 and Enamul Huq1 1Section of Molecular Cell and Developmental
Biology and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA. 2Section of Cell and
Developmental Biology, University of California at San Diego, La Jolla, CA, 92093. Ubiquitin (ubi)-mediated proteolysis has been found to
play critical roles in controlling plant growth and development. Approximately 5% of the cellular proteome are components of this pathway,
and are involved in multiple developmental, environmental and biotic responses, including cell cycle, embryogenesis, flower development,
hormone signaling, light signaling and circadian rhythm, defense responses and senescence in Arabidopsis. However, direct involvement of
this pathway has not been shown for responses of plants to abiotic stress conditions. Here we show that MAX2, an F-box protein regulates
abiotic stress tolerance in Arabidopsis. Three independently isolated alleles of max2 mutant show striking sensitivity to drought conditions.
max2 mutant plants lose water much faster than the wild type plants. This is partly due to a decreased sensitivity to exogenously applied
ABA in closing stomatal aperture. MAX2 has been shown to control multiple developmental and environmental responses, including apical
dominance, senescence and photomorphogenesis at different stages of development. These results suggest that MAX2 might regulate
multiple targets at different developmental stages to optimize plant growth and responses to abiotic stress conditions.
(a) Section of Molecular Cell and Developmental Biology and The Institute for Cellular and Molecular Biology, University Of Texas at Austin
(b) Section of Cell and Developmental Biology, University of California at San Diego
P10027 Overexpression of Arabidopsis Damaged DNA Binding protein 1A (DDB1A) enhances DNA repair
Alkhateeb, Wesam M-presenter [email protected](a)
Schroeder, Dana F (a)
DDB1 is a component of multiple complexes involved in genome stability, cell cycle regulation, histone modification, DNA replication and
repair. Arabidopsis has two homologues of DDB1: DDB1A and DDB1B. In this study we examine the role of DDB1A in Arabidopsis DNA
repair using a DDB1A null mutant (ddb1a) and overexpression lines generated using the CaMV 35S promoter. While UV tolerance assays
showed no significant difference between wildtype plants and ddb1a mutants, a slight delay in repair of (6-4) photoproducts was detected
in ddb1a mutants. DDB1A overexpression lines however exhibited higher levels of UV-resistance as well as faster DNA repair than wildtype.
Following UV exposure DDB1A mRNA levels increase significantly in wildtype and overexpression lines. DDB1B and DDB2 mRNA levels also
increased after UV exposure in wildtype, but induction was not observed in the DDB1A loss of function background. In conclusion, these
results indicate that DDB1A plays an important role in Arabidopsis damaged DNA repair and UV response.
(a) University of Manitoba, Department of Biological Sciences. Winnipeg, MB. Canada
P10028 Ectopic expression of annexin from Brassica juncea confers tolerance to multiple stresses in transgenic tobacco
Clark, Gregory Bland-presenter [email protected](a)
Jami, Sravan K (b)
Handley, Craig (a)
Cantero, Araceli (a)
Kirti,
Pulugurtha B (c)
Roux, Stanley J (a)
Annexins are calcium-dependent membrane binding proteins that appear to play diverse roles in a wide variety of physiological responses.
Recent findings indicate that certain plant annexins may play a key role during stress responses. For example, proteomic and genetic data
implicate AnnAt1 as an important component of osmotic stress signaling in Arabidopsis. To determine if the Brassica homolog of this
annexin, AnnBj1, functions in protection against stress, we generated transgenic tobacco plants ectopically expressing AnnBj1 under the
control of CaMV 35S promoter. The transgenic tobacco plants showed significant tolerance to dehydration, salt, heavy metal and oxidative
stress at the seedling stage. In detached leaf senescence experiments, these transgenic plants showed higher chlorophyll content compared
to wild-type plants under these stresses. AnnBj1 recombinant protein exhibited low levels of peroxidase activity in vitro and total extracts of
leaves from transgenic plants showed higher levels of peroxidase activity compared to leaves from wild-type plants. In leaf disc
experiments, the transgenic plants also showed decreased lipid peroxidation levels compared to wild-type plants in response to mannitol
treatments. Additionally, the transgenic plants showed enhanced resistance to the oomycete pathogen, Phytophthora parasitica var.
nicotianae and increased message levels for several pathogenesis-related proteins. We will present results demonstrating that ectopic
expression of AnnBj1 in tobacco provides tolerance to a variety of abiotic and biotic stresses. Supported by NASA grant NAG2-1586 and APNL Biotechnology program Hyderabad, India.
(a) University Of Texas (b) University of Manitoba (c) University of Hyderabad
P10029 Serpins in rice: Clues to function from responses to abiotic stresses
Ersoy, Renan A-presenter [email protected](a)
Roberts, Thomas H. (a)
Atwell, Brian (a)
Serpins are a large family of proteins found in all domains of life and are ubiquitous in multicellular eukaryotes. They are known to regulate
a diverse range of biological processes in animals, mainly through inhibition of serine (rarely cysteine) proteinases. Inhibitory serpins are
known as suicidal proteins because they undergo massive, irreversible conformational change as part of their mechanism to form stable
covalent complexes with target proteinases. Extensive studies have been performed to determine the biochemical properties of plant serpins
but no physiological functions have been established and no confirmed in vivo proteinase targets discovered. We have identified 14 serpin
genes in the fully sequenced genome of rice (Oryza sativa L. cv. Nipponbare) by PSI-BLAST searching. Eleven out of 14 genes appear to
encode inhibitory serpins. Each of these serpin contains a characteristic amino acid sequence in the reactive centre, suggesting a diversity
of target proteinases and therefore a range of functions. Of the eight serpin genes chosen for analysis, a serpin with LRS as P2-P1 was
expressed at the highest levels during seedling development; other serpin genes were relatively weakly expressed. Similar patterns of basal
expression were obtained for adult leaves, stems and roots. A range of plant treatments is being tested to determine their effect on LRS
serpin gene expression, including cold, drought, salt, heat, wounding, and exposure to DNA-damaging reagents. Results of these
experiments and other data on rice serpin gene expression are providing critical clues to function. We are also silencing the LRS serpin for
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both phenotype comparisons to wildtype plants and whole genome expression analysis using microarrays.
(a) Macquarie University
P10030 Enhanced expression of genes for ACC synthase, ACC oxidase, and NAC protein during high-temperature-induced
necrosis of young inflorescences of Cymbidium
Mita, Satoru-presenter [email protected](a)
Ohno, Hajime (b)
Growing Cymbidium under high-temperature conditions (25-30 degrees C above zero) results in the necrosis of young inflorescences. An
increase in the evolution of ethylene was correlated with the necrosis. To study the molecular aspects of high-temperature-induced necrosis
of Cymbidium floral buds, we isolated cDNA clones for proteins that are likely to be involved in the biosynthesis of ethylene during hightemperature-induced necrosis of young inflorescences, namely, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (CyACS1) and ACC
oxidase (CyACO1). In addition, a cDNA (CyNAC1) encoding an NAC protein whose expression is modulated during high-temperature
treatment was isolated by differential display. High levels of expression of CyACS1, CyACO1 and CyNAC1 were observed in the necrotic
inflorescences of wild-type Cymbidium at high temperatures. Bud necrosis was not observed in the mericlone mutant (nhn, non-hightemperature-induced necrosis) of Cymbidium. Ethylene evolution was lower in nhn than in wild-type, but application of exogenous ACC or
ethephon to the young inflorescences of nhn restored the high-temperature necrosis response. Expression of CyACS1, CyACO1 and CyNAC1
did not increase with high-temperature treatment in the nhn mutant. Expression levels of CyACS1, CyACO1 and CyNAC1 in necrotic
inflorescences of nhn treated with 5.0 mM ACC were much lower than in necrotic inflorescences of wild-type at high temperatures, but
CyACS1 and CyNAC1 were stimulated by ACC treatment. These results suggest that ethylene is involved in high-temperature necrosis of
young inflorescences of Cymbidium and that an NAC protein may be involved in the regulatory mechanisms of genes that are regulated
during necrosis.
(a) Institute for Genetic Research and Biotechnology, Shizuoka University (b) Faculty of Agriculture, Shizuoka University
P10031 Regulatory clusters involved in the early responses of japonica rice to chilling
Herath, Venura-presenter [email protected](a)
Park, Mayong R (a)
Yun, Kil-Young (a)
Magoon, Daniel
(a)
Mohanty, Bijayalaxmi (b)
Xu, Fuyu (a)
Mauleon, R (c)
Bajic , Vladimir (b)
Bruskiewich, Richard (c)
De los Reyes, Benildo
(a)
Rice and Arabidopsis, two of the widely used plant genetic models, have contrasting sensitivities to low temperature. Rice is generally very
sensitive to temperatures below 10oC, while Arabidopsis is quite tolerant to similar degree of cold stress and has evolved mechanisms to
withstand freezing by cold acclimation (CA) at temperatures around 4oC. The regulatory networks that configure the CA transcriptome of
Arabidopsis have been the subject of scientific scrutiny during the last decade and these involved three major upstream regulators such as
CBF1, ZAT12, and RAV1. In rice, transcriptome profiling data indicated that rapid response is an important aspect of short-term defense
mechanisms and that the timing by which regulatory clusters are activated is highly correlated with the differential sensitivity of temperate
japonica (tolerant) and tropical indica (intolerant) subspecies to chilling. The composition of regulatory clusters induced at 10oC in rice
appears to be distinct from those that configure the long-term CA response at 4oC in Arabidopsis. The early response regulatory clusters in
rice appear to be a direct manifestation of chilling-induced oxidative stress. The component regulators (ROS-bZIP, OsRAV1) and
downstream targets of the putative rice regulons have been inferred by integrative analysis of temporal expression profiles and ab initio
scanning of cis-regulatory elements among co-regulated genes. Results are validated experimentally by promoter deletion and protein-DNA
binding analyses and by signal-independent activation of regulatory clusters by overexpression of transcription factors. This study is
expected to contribute to the understanding of the genetic changes that gave rise to a gradient of low temperature sensitivity in higher
plants.
(a) School of Biology and Ecology, University of Maine, Orono ME 04469 (b) South African National Bioinformatics Institute, The University
of the Western Cape, South Africa (c) Crop Research Informatics Laboratory, The International Rice Research Institute, Philippines
P10032 Genetic and evolutionary analyses of the Sub1 gene cluster that confers submergence
Harris, Tristan G-presenter [email protected](a,b)
Fukao, Takeshi (a,b)
Bailey-Serres, Julia (a,b)
Submergence-1 (Sub1) is a major locus that affects submergence tolerance in rice (Oryza sativa). Sub1 encodes up to three ethylene
response factor-like genes: Sub1A, Sub1B, and Sub1C. The Sub1A-1 allele of the Sub1A gene was shown to confer submergence tolerance
through a quiescence response. Rice genotypes lacking the Sub1A gene respond to submergence stress by carbohydrate consumption and
shoot elongation, resulting in carbohydrate starvation and an energy crisis under prolonged submergence. Here, we evaluated the influence
of another Sub1A allele, Sub1A-2, on submergence response. IR64 is an indica inbred line which contains Sub1A-2 on the Sub1 locus,
whereas the Sub1 locus of IR64(Sub1) is introgressed from submergence-tolerant accession, FR13A, which has Sub1A-1. Our submergence
test confirmed that Sub1A-1 restricted underwater elongation and enhanced submergence tolerance as compared with Sub1A-2.
Interestingly, both Sub1A-1 and Sub1A-2 transcripts were induced in abundance during submergence, but the level of Sub1A-2 transcript
was significantly less abundant over 14 d of submergence. Consistent with the observation, transcript accumulation of α-amylase and
expansin A genes were restricted in IR64(Sub1) under submerged conditions. These data suggest that the transcript level of Sub1A gene
determines distinctions in submergence response and submergence tolerance in rice. In addition, we revealed that Sub1B and Sub1C genes
are present in O. nivara and O. rufipogon, the direct progenitors of O. sativa, but they lack Sub1A. Transcripts of Sub1B and Sub1C were
accumulated in response to 3 d of submergence in aerial tissue of O. nivara. Phylogenetic analysis suggests that Sub1A arose from
duplication of Sub1B.
(a) Department of Botany and Plant Sciences, University of California, Riverside (b) Center for Plant Cell Biology, University of California,
Riverside
P10033 Light irradiation down-regulates glutathione levels in cold-acclimated mung bean seedlings.
Hung, Shu-Hsien (a)
Fang, Jhen-Cheng (b)
Yu, Fu-Chung (a)
Yu, Chih-Wen -presenter [email protected](b)
Application of a 8oC, 36 h-chilling in dark resulted in a 2-fold increase in the glutathione (GSH) levels in 7-d-old mung bean seedlings,
compared to 25oC control plants. Interestingly, white-light irradiation inhibited the GSH accumulation under the same treatment. The
inhibitory effect of light on GSH level was enhanced with the increasing of light intensity and reached the maximal level at 100 μmol m-2 s1. Whereas this light-dependent inhibitory effect declined when the white-light intensity more than 100 μmol m-2 s-1. Noteworthily,
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electrolyte leakage analysis showed that the light-reduced GSH accumulation had no negative impact on the cold tolerance of 8oC, 36 hchilled seedlings. A combination of 8oC, 36 h-chilling and 100 μmol m-2 s-1 red (640-660 nm) or blue light (420-460 nm) further revealed
that only red light was capable of inhibiting GSH accumulation in mung. These results suggest that in addition growth and development, red
light also involves in cold hardiness of plants.
(a) Department of Bioindustry Technology, Da-Yeh University, Chunghua, Taiwan (b) Department of Molecular Biotechnology, Da-Yeh
University, Chunghua, Taiwan
P10034 Comparative transcriptional changes of mungbean, Vigna radiata (L.) Wilczek, seedlings in response to cold
Lin, Tsai-Yun-presenter [email protected](b,a)
Chen, Li-Ru (b,a)
http://life.nthu.edu.tw/~lslty/
Cold stress impacts severely on the agricultural productivity of tropical and subtropical plants. The response of cold tolerance or
susceptibility involves extensive and diverse transcriptomic reprogramming, metabolomic configuring and physiological remodeling.
Mungbean (Vigna radiata (L.) Wilczek) is an important tropical crop which is susceptible to cold stress. The mungbean variety NM94
maintains better membrane integrity than the variety VC1973A upon exposure to cold at the seedling stages. We developed 811 early
developmental and stress responsive expressed sequence tags (ESTs) from mungbean seedlings and prepared a small scale cDNA
microarray containing 735 uniESTs. To uncover the molecular mechanisms of the inherent susceptibility to cold, we perform a comparative
analysis of gene expression in young seedlings of NM94 and VC1973A during cold stress and after recovery from cold. Upon exposure to
cold, NM94 and VC1973A triggered a common set of cold regulated genes involving in restructuring the protein synthesis apparatus and
cryoprotection, or participating in protein trafficking, degradation and the biosynthesis of stress protectants like anthocyanins and
polyamines. The early transcriptional activation of dehydrin, plant defensins, lipid transfer proteins and photosynthetic proteins may
contribute to protect membrane integrity of NM94 against cold stress. The comparative transcriptional changes are informative to identify
the molecular events in the different susceptibility to cold of the tropical crops.
(a) National Tsing Hua University, Department of Life Science (b) National Tsing Hua University, Institute of Bioinformatics and Structural
Biology
P10036 Changes in proteome, soluble sugars and cell wall composition in roots of Eucalyptus grandis induced by water
defict
Labate, Carlos Alberto-presenter [email protected](a)
Andrade, Alexander (a)
Bonatto, Jose M.C. (a)
Salvato, Fernanda
(a)
Camargo, Eduardo L.O. (a)
Boaretto, Luis F (a)
Bragatto, Juliano (a)
The water deficit represents an important abiotic factor affecting the development and productivity of many forest plantations throughout
the world. Drought tolerance in plants is becoming increasingly important, particularly in developing countries, due to climate changes and
the need to occupy dry marginal areas not used for agriculture and forest. To investigate the initial response of Eucalyptus grandis to
drought stress, changes in the protein and cell wall composition were analyzed using proteomic and metabolic approaches. Six-month-oldplants were exposed to drought conditions for seven days and total proteins, soluble sugar and cell wall carbohydrates and lignin were
extracted from the roots. The proteins were separated by 2D-PAGE. The differentially expressed proteins were identified by LC-MS/MS.
Soluble sugars and carbohydrates were separated and quantified by HPLC. The results showed that after seven days of drought, 62 proteins
displayed significant changes in the expression. Forty proteins were upregulated and 22 showed a reduced level of expression. The content
of soluble sugars of the roots was strongly altered by water stress. The amount of soluble sugars and starch decreased, whereas fructose
and glucose increased under water stress. Cell wall polysaccharides did not change with stress. However, after 10 days of water deficit the
amount of soluble and insoluble lignin increased significantly in stressed roots. These results show a coordinated response to drought stress,
leading to changes in the level of carbohydrate and proteins.
(a) Max Feffer Laboratory of Plant Genetics, Department of Genetics, ESALQ, University of Sao Paulo
P10037 Transcriptomic responses to aluminum stress in roots of Arabidopsis thaliana
Kumari, Manjeet-presenter [email protected](a)
Taylor, Gregory J (a)
Deyholos, Michael K (a)
http://www.biology.ualberta.ca/faculty/michael_deyholos/?Page=4796
We present the first, large-scale, transcriptomic analysis of root responses to aluminum (Al), using a microarray with probes representing
approximately 93% of the predicted genes in the genome of Arabidopsis. More transcripts were responsive to Al (25 μM) during long (48h,
1114 genes), as compared to short (6h, 401 genes) exposures, which contrasts with previous microarray analyses of plant response to
abiotic stress. Exposure to Al triggered changes in the transcript levels for several genes related to oxidative stress pathway, membrane
transporters (e.g. aquaporins and ABC transporters), cell wall, energy, and polysaccharide metabolism(e.g. glycoside hydrolases and
glycosyl transferases). Interestingly, lack of abundance of transcripts encoding TCA cycle enzymes, except for malate dehydrogenase,
suggested that synthesis of organic anions in response to Al may not be transcriptionally regulated. Al exposures induced differential
abundance of transcripts for several ribosomal proteins, peptidases and protein phosphatases mostly after 48h. We also detected increased
abundance of transcripts for several membrane receptor kinases and non-membrane calcium response kinases, which could play a role in
transmission of Al-stress signals. Among Al responsive transcription factors, the most predominant families identified were AP2/EREBP, MYB
and bHLH. Results of this screen contribute to the identification of candidate genes for the generation of Al-tolerant transgenic plants.
(a) Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G2E9
P10038 Systemic nature of drought-tolerance in common bean
Xoconostle-Cazares, Beatriz-presenter [email protected](a)
Ruiz-Medrano, Roberto (a)
The response to drought at the physiological and molecular levels was studied in two common bean varieties with contrasting susceptibility
to drought stress. A number of genes were found to be up-regulated in the tolerant Phaseolus vulgaris variety Pinto Villa relative to the
susceptible cultivar, Carioca. The products of these genes fell in different functional categories. The analyses of selected genes, consisting
of their differential expression and in situ mRNA accumulation displayed interesting profiles. The tolerant displayed a more developed root
vasculature in drought conditions, when compared to the susceptible, tropical bean Carioca. In situ localization of three selected mRNAs
indicated their accumulation in companion cells, sieve tubes and in developing phloem, suggesting that these, and/or the encoded proteins
could constitute phloem-mobile signals. Indeed, a number of transcripts that are induced in response to water deficit accumulate in the
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phloem in other plant species, suggesting a general phenomenon. Moreover, the analysis of drought stress in plant varieties with
contrasting tolerance will help to determine the role of specific genes, as well as other biochemical, morphological and physiological traits.
Drought-tolerant plants likely evolved a system that would allow them to maintain its vascular tissue integrity under stress. A functional
phloem may then still be useful for the transmission of long-range signals, which would be important for the systemic adaptation to the
stress. It would then be expected that plants showing increased tolerance to abiotic stress, such as drought, are able to better protect their
conductive tissues. This general strategy could help these plants evolve in stress conditions and successfully colonize new habitats.
(a) Biotecnologia y Bioingenieria, Cinvestav IPN
P10039 Gene expression profiling during low-oxygen acclimation of Arabidopsis reveals an intricate relationship of small
HSPs expression with flooding tolerance
Hwang, Ji-Hye (a)
Hwang, Hyo-Joo (a)
Lee, Dong Hee-presenter [email protected](a)
Low-oxygen condition is the primary plant stress in flooded soil. Plants have developed adaptation mechanisms at both the physiological
and the structural levels to enhance their ability to survive low-oxygen stress. The effect of the low-oxygen stress on Arabidopsis was
investigated at growth and gene expression level. To gain insight into how plants respond to low-oxygen, we analyzed the gene expression
patterns of Arabidopsis using Operon microarray (70-mer oligonucleotide). Gene expression profiling was carried out at five time point
under hypoxic stress in root of Arabidopsis Columbia(Col-0). Hypoxic-responsive genes (HRG) were selected in gene expression profiling.
Genes coding for heat stress related gene such as heat stress transcription factor, heat shock protein were induced, mostly at the level of
small HSPs, during low-oxygen acclimation. In addition pretreatment of heat stress strongly enhances tolerance to low-oxygen stress.
Functional analysis of small HSPs will lead to a more comprehensive understanding of the mechanism of flooding-tolerance and reveals
genes that may be important to enhance the flooding tolerance and will be used to develop the flooding-resistant plants.
(a) Ewha Womans University
P10040 Effect of salinity on ω3 desaturase genes expression and LNA/LA content in Portulaca oleracea L. leaves
Teixeira, Monica C-presenter [email protected](a,b)
Olsson, Mikael E (b)
Brodelius, Peter (b)
Carvalho, Isabel S
(a)
Brodelius, Maria (b)
Purslane (Portulaca oleracea L.) is a vigorous colonizer of disturbed waste habitats and has been rated as a salt tolerant plant. Purslane is
the richest source of lipids, among edible members of Centrospermae, with a high ω3/ω6 ratio. The shoot is a rich source of ω3 fatty acids,
α-tocopherol, ascorbic acid, β-carotene, and glutathione. Here we measured the effect of saline stress in plant yield, ω3 desaturase genes
expression and linolenic acid (LNA) content in leaves. Relations between salinity, gene expression and LNA/LA levels were studied. Plants
were exposed to 4 levels of chloride-salinity on the root-zone (60, 90, 120 and 240 mM NaCl) and followed through different phases of
development. Plant relative yield was affected up to the stage before flowering and kept constant towards the end of the experiment. A 1015% yield reduction was obtained at 60 mM NaCl and a 50% yield reduction was achieved only for the highest salinity treatments. No
chloride-salinity toxicity signs or plant death were observed in any of the treatments, an indication of the high tolerance to saline
environment of this plant. In this work, the relative expressions of all ω3 desaturase genes: FAD3, FAD7 and FAD8 genes were significantly
affected by the salt treatment. RT-qPCR analysis showed that an increase of the expression was observed in the lowest salinity treatment,
60 mM NaCl, and also at 90 mM NaCl. Down-regulation of these genes was observed at 120 and 240 mM NaCl. LNA accumulation in leaves
was measured by GC-MS and was in agreement with the changes in gene expression level. Increase of the expression of ω3 desaturase
genes, as a response to moderate salinity conditions, could be seen an important adaptation response in harsh environments.
(a) University of Algarve - Institute for Biotechnology and Bioengineering (b) University of Kalmar - School of Pure and Applied Natural
Sciences
P10041 Role of thiol-disulfide oxidoreductases in aluminum and cadmium tolerance in yeast and Arabidopsis
Lopez Santiago, Diana L-presenter [email protected](a)
Taylor, Gregory J (a)
Basu, Urmila (a)
Aluminum (Al) is one of the major factors limiting plant growth on acid soils. Increased production of reactive oxygen species (ROS) has
been linked to the toxic effects of Al in plants. Cadmium (Cd) is also a phytotoxic metal that can also elicit a ROS response. Oxidative
damage in plants exposed to Al and/or Cd suggests that the plants antioxidant system is unable to detoxify Al and Cd-induced ROS. We
have focused on the thiol-disulfide oxidoreductases (TDORs). These antioxidant enzymes are able to maintain cellular redox homeostasis by
repairing oxidatively damaged proteins and scavenging ROS. Using yeast ( Saccharomyces cerevisiae ) as a model system, we have
identified a subset of TDORs. Fifteen single disruption mutants in yeast defective for thioredoxins, thioredoxin reductases, thioredoxin
peroxidases or glutaredoxins were screened for hypersensitivity to Al and/or Cd. Mutants defective in thioredoxin reductase, two
peroxiredoxins, and a glutaredoxin showed hypersensitivity to both stresses. The thioredoxin reductase mutant showed the strongest
phenotype resulting in 60% inhibition in growth. Complementation of this mutant with the yeast thioredoxin reductase restored growth to
wild-type levels. Northern analyses showed increased expression of thioredoxin reductase in wild-type yeast exposed to Al or Cd.
Hypersensitivity to Al and Cd was further increased up to 20% in double and triple yeast mutants of the 4 identified genes. Subsequently,
Arabidopsis knock out lines (SALK lines) of the genes identified in yeast were screened for Al and Cd sensitivity, and only lines defective in
two thioredoxin reductases had increased sensitivity to Al and Cd. Transgenic Arabidopsis lines overexpressing these two thioredoxin
reductases are currently being tested.
(a) University of Alberta
P10042 Mechanisms of salinity tolerance in barley
Newman, Ian A.-presenter [email protected](a)
Chen, Zhonghua (a)
Pottosin, Igor I. (b)
Shabala, Sergey (a)
http://www.mife.com
Most plants attain salinity tolerance by maintaining a high enough ratio of K+ to Na+ in the cytosol, using a number of mechanisms.
Recently we have identified (Chen et al. Plant Phys. 145, 1714) a coherent set of membrane related processes and their interactions, that
contribute to salinity tolerance in barley. From glasshouse and laboratory screening of 70 cultivars, ranging from highly tolerant to very
sensitive, three genotypes from each extreme were selected. Plant responses to Na+ treatment were compared to control responses using
a range of techniques: electrophysiological (membrane potential; microelectrode ion flux; patch-clamp), biochemical (ATP content and
activity in root cells), physiological (photosynthesis; transpiration; solution depletion rate; flag leaf sap Na+ and K+; influx of 22Na) and
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agronomical (growth & germination rate; biomass; grain yield). Here we present a model that highlights underlying ionic mechanisms
contributing to salinity tolerance in barley and identifies key transporters for possible genetic or breeding manipulation. On our scenario,
Na+ uptake by root cells causes PM depolarisation, which opens outward rectifying K channels leading to loss of K+. The depolarisation also
stimulates the PM ATPase to extrude H+ that, with the K+ loss, tends to limit the depolarisation or even to reverse it. The PM pH gradient
enhanced by the H+ extrusion can drive a SOS1-like H/Na exchanger to remove some of the Na+ taken up. The strength of every one of
these processes and their interactions helps to determine the place of the cultivar in the sensitive to tolerant spectrum.
(a) University of Tasmania, Hobart, Australia (b) Universidad de Colima, Colima, Mexico
P10043 Does aluminum accumulate in Conostegia xalapensis (Melastomataceae)?. Effects of Al on growth and antioxidant
system.
Gonzalez-Santana, Iris Hayde-presenter [email protected](a)
Cruz-Ortega, Rocio (a)
In acid soils, the excess of soluble Al (Al3+) restricts plant growth. Some plants tolerate high Al3+ concentrations. In Melatomataceae
family Melastoma malabathricum shows intrinsic tolerance mechanisms that allow it to accumulate Al in their tissues, without any damage.
Plants that accumulate more than 1000 mgkg-1Al in their tissues are Al accumulator plants, Camellia sinencis accumulates 30 mgg-1Al in
adults leaves, and only 0.6 mgg-1Al in youngest. Also, the genus Conostegia (Melastomataceae) has been reported as Al accumulator
plants. C. xalapensis is a shrubs very common in Mexico and Centroamerica, colonizing disturbed sites. In this work we evaluated whether
C. xalapensis is an Al accumulator plant and if presents intrinsic tolerance mechanisms. We determined the concentration of Al in mature
leaves of C. xalapensis collected in Totonacapan Region, Ver. Mex. We found that C. xalapensis accumulated 12491 mgkg-1Al in mature
leaves and in young leaves 686 mgkg-1Al. We also performed a growth experiment in which we treated seedlings of C. xalapensis with 0.5
and 1.0 mM AlCl3 in culture solution. We evaluated root growth and the formation of new lateral roots. Activity of CAT and APX, and the
concentration of H2O2 in leaves and roots was also measured. Al was localized in leaves and roots using PCV and Hematoxylin stain. Root
growth was not inhibited in both Al treatments, but the number of new roots was higher in Al treatments than in controls. CAT activity in
leaves and roots was higher in both treatments, and levels of H2O2 were low. Al was localized in mesophyll of leaves and epidermal cells of
roots. In conclusion, C. xalapensis could be considered as Al accumulator plant, and perhaps their antioxidant system is able to alleviate the
effects toxicity of Al.
(a) Instituto de Ecologia. UNAM
P10044 Rice plants expressing Datura S-Adenosylmethionine Decarboxylase accumulated high levels of spermine and
exhibited a drought tolerant phenotype
Peremarti Brosel, Ariadna-presenter [email protected](a)
Bassie, Ludovic (a)
Yuan, Dawei (a)
Dashevskaya, Svetlana
(a)
Christou, Paul (a)
Capell, Teresa (a)
A proposed mechanistic model explaining the role of polyamines in abiotic stress tolerance in cereal plants, calls for a high putrescine pool
which is converted to spermidine and subsequently to spermine, the postulated protective compounds, upon the onset of stress. For
drought (abiotic) stress experiments rice (Oryza sativa L. cv EYI105) plants transformed with the Datura S-Adenosylmethionine
Decarboxylase cDNA and containing higher level of spermidine and spermine were selected. Each independent transformant was
characterized molecularly and biochemically. Putrescine content in these plants was similar to wild type. We demonstrate that plants with
initial higher levels of spermidine were able to convert this triamine to spermine when subjected to drought stress. Such plants were able to
recover and to initiate new growth much better after the stress stimulus was removed compared to wild type plants. This protective
response was not as pronounced phenotypically as in the case of plants with high levels of putrescine. However a remarkable effect in
terms of development was observed, manifested as an increase in the number of tillers formed on the transgenic plants. Our studies
confirm that even in the absence of a high initial putrescine pool, plants with enhanced levels of spermidine exhibit tolerance towards stress
following removal of the stimulus.
(a) Departament de Produccio Vegetal i Ciencia Forestal. ETSEA. Universitat de Lleida.
P10045 Drought/Heat Tolerance Variation and Genetic Diversity in a xerophyte species, purslane (Portulaca spp)
ren, shuxin-presenter [email protected](a)
Akande, Omololu (a)
Mebrahtu, Tadesse (a)
Drought and heat stresses are the major abiotic factors that affect crop production. Given the reduction in available water resources and the
repercussions of global warming, drought and heat stresses continue be the primary concerns for agriculture. However, genetic modification
for such traits has not yet been successful due to lack of unique genetic resources. Purslane (Portulaca spp.) is widely distributed
throughout the world. It is a xerophyte species that grows in extreme drought and hot conditions. Understanding the basis of this xerophyte
species in tolerating high drought/heat stresses will help us to develop new strategies for sustainable crop improvement under certain
circumstance. Genetic variations of drought/heat tolerance among 11 purslane accessions, collected from geographically different regions of
the world, were evaluated. Our study identified two accessions, one is Eritrea Tokomba, the other Egypt, with discrete mechanisms in
tolerating drought stress. The heat tolerant phenotypes among different accessions were also varied significantly and were not always
coupled with drought tolerance. AFLP-based biodiversity study indicated that Eritrea Tokomba accession alone form a unique group and
clearly separate from others. In addition, within the rest of 10 accessions, Egypt is also genetically distinct from other accessions. Our
results suggest that, although purslane is a xerophyte species with drought/heat tolerance ability, the significant genetic variations on these
phenotypes still exist among accessions and this genetic diversity at molecular level will provide us the opportunity to identify new
components regulating plant defending against such environmental stresses
(a) Virginia State University
P10046 Heat stress induces autophagic programmed cell death of microspore mother cells and uninucleate microspores in
Oryza sativa (var. japonica)
Sage, Tammy L-presenter [email protected](a)
Bagha, Shaheen (a)
Sault, Kathy (a)
Li, Angela (a)
Chiu, Greta (a)
Rice reproduction currently occurs within a few degrees of the temperature threshold for reproductive failure and with predicted climate
warming, much of the worlds rice crop could be exposed to temperatures causing sterility. In the present study, we investigated the impact
of 32C and 36C on grain yield and pollen development in rice. We demonstrate that an increase in daytime temperatures of only 4C trigger
severe yield reductions by distinctly different developmental processes. Failure in rice reproduction at 32C is due to anther indehiscence
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with minimal impact on pollen development, processes previously reported for rice and other monocots and eudicots. In contrast, yield
reductions at 36C were due to an absence of viable pollen production. Failure in pollen development occurred at two phases,
microsporogenesis and microgametogenesis. Abortion during microsporogenesis was initiated prior to meiosis but after development of
microspore mother cells. Miscarriage during microgametogenesis was at the uninucleate stage. Initial failure at microsporogenesis occurred
in the absence of abnormalities in surrounding anther cell layers, whereas pollen abortion during microgametogenesis was coincident with
alterations in tapetal maturation. In each case, aborted development resulted from the dismantling of the cytoplasm and nucleus of
microspore mother cells and microspores via autophagic processes that resemble autophagic programmed cell death (PCD) versus necrosis.
Detection of apoptosis using the formamide-monoclonal antibody to ssDNA assay confirmed the presence of apoptosis.
(a) University of Toronto
P10047 Cell cycle dependent responses to cold of Arabidopsis thaliana suspension cultured cells
Sasaki, Yutaka (b)
Uemura, Matsuo-presenter [email protected](b,a)
Arabidopsis suspension cultured cells increase freezing tolerance when subjected to low temperatures or incubated with exogenous ABA.
The increase of freezing tolerance is detected only with cells at the lag growth phase but not with cells at the log phase. Lag phase cells had
eventually high frequency of cell cycle progression than log phase cells, suggesting that differences of cold responses in Arabidopsis cells at
the growth phases is likely related to the cell cycle stage and/or progression. To investigate cell-cycle dependent cold-responses, we first
established a protocol to synchronize the Arabidopsis cultured cells with aphidicolin and then found that cold-responsive gene expression
was higher in cells at the S and G1 phases than at the G2/M phase. Furthermore, accumulation of endogenous ABA was detected only in
cells at the G1 phase. Lastly, freezing tolerance was quite different among cells at different cell cycle stages. S phase cells exhibited the
greatest tolerance both before (60% survival at -7C) and after (50% at -9C) and survival of G1 phase cells increased from 50% at -4C
before cold treatment to 60% at -5C. In contrast, there was no effect of cold treatment on freezing tolerance in G2/M phase cells (50 to
60% at -4C). These results strongly indicate that cold response of cultured cells is dependent on cell cycle in Arabidopsis T87 cultured cells.
(Supported by Grants from JSPS and MEXT, Japan)
(a) Cryobiofrontier Research Center, Iwate University (b) United Graduate School of Agricultural Sciences, Iwate University
P10048 Proteome analysis of leaves of the desiccation-tolerant grass, Sporobolus stapfianus, in response to desiccation.
Oliver, Mel J-presenter [email protected](a)
Jain, Renuka (d)
Agrawal, Ganesh (b)
Gasulla, Francisco (c)
Thelan, Jay
(b)
Sporobolus stapfianus is a resurrection grass native to South Africa which can tolerate the complete drying of its vegetative tissue structure,
i.e. desiccation, and recover fully within hours of rewetting. Gene expression studies have demonstrated that the grass employs a strategy
of gene induction during drying that presumably allows for the grass to amass proteins that are directed at protecting the cell during the
desiccation process. Much of this work has utilized transcript profiles to infer the nature of the gene products that are derived from the
drying induced genes. Little in the way of direct protein identification has been employed in such assessments. To identify those proteins
that accumulate in desiccation tolerant leaf tissues during the drying process, we have employed a strategy of 2-D Difference Gel
Electrophoresis (DIGE) coupled with individual protein identification using trypsin digestion (from silver stained replicates) and LC-MS/MS.
The DIGE strategy allows us to identify those proteins that are not present in the fully hydrated unstressed leaves but are in air-dried
tissues. Our analysis was able to detect 95 differentially expressed proteins: 41 exhibit statistically significant accumulation during drying
and 54 are significantly depressed in level as a result of desiccation. Of these proteins, using the Oryza sativa non-redundant database, we
were able to reliably identify 77 from the MS/MS spectra of trypsin digest derived peptides. Protein identities suggest roles for energy
metabolism, sugar metabolism, protein degradation and the possible sequestration of important chloroplastic proteins in the mechanism of
vegetative desiccation tolerance employed by this resurrection grass.
(a) USDA-ARS Plant Genetics Research Unit (b) University of Missouri (c) Universitat de Valencia (d) Avesthgen Limited, Bangalore, India
P10049 Chlorophyll fluorescence imaging: A non-invasive tool to assess Oryza sativa tolerance to excess iron.
Pereira, Eduardo G. (a)
Mendes, Giselle C.-presenter [email protected](a)
Colares, Denise (b)
Stopato, Carlos H.
(a)
Souza, Laise R. (a)
Costa de Oliveira, Antonio (b)
Oliva, Marco A. (a)
Almeida, Andrea M. (a)
Iron in excess can became phytotoxic mainly in flooded soils as is the system of rice culture. Selection of iron-excess tolerant genotypes can
increase the area of culture and the rice productivity. This work aimed applying chlorophyll fluorescence imaging as a non-invasive genotype
selection tool. Four O. sativa genotypes from two breeding programs (IRGA409 and IRGA412 from Southern Brazil; BRA041171 and
BRA041152 from Central-South Brazil) were grown in Hoagland nutrient solution and Fe-EDTA 7 mM was applied when plants reached 30
days old. After 7 days treatment shoot and root iron content, gas exchange and the chlorophyll a fluorescence parameters were evaluated.
Basic fluorescence (F0); potential quantum yield of photosystem II (Fv/Fm), non-photochemical quenching (NPQ) and photochemical
quenching (qP) were evaluated using modulated fluorometer imaging-PAM. The leaf surface was divided in three areas of interest: center,
right and left side. The genotypes showed increases in shoot and root iron content at the following order: IRGA409<IRGA412<BRA0411520
and NPQ, indicatives of injuries in the photosynthetic apparatus, showed imaging variation in response to the genotype and iron treatments,
making these two parameters the most adequate to evaluate genotype response to iron. The most sensitive genotypes BRA041152 and
BRA041171 from Central-South Brazil also accumulated more iron and had a more pronounced net CO2 assimilation decrease. These data
showed that chlorophyll fluorescence imaging can be used to determinate excess iron tolerance in rice genotypes. Financial support: CAPES.
(a) Departamento de Biologia Vegetal, Universidade Federal de Vicosa, Vicosa MG, Brazil. (b) Centro de Genomica e Fitomelhoramento,
Universidade Federal de Pelotas, Pelotas RS, Brazil.
P10050 Differential root proteomic analysis indicate several proteins involved in drought stress response in Coffea
canephora genotypes
Soares, Carla Q. G. (a)
Guimaraes, Breno L. S. (a)
Valente, Richard H. (b)
Vieira, Mauricio A. (a)
Soares, Eduardo A
(a)
Araujo, Sabrina H. C. (a)
Silva, Vania A. (a)
Fontes, Elizabeth P. B. (c)
Loureiro, Marcelo E. (a)
Almeida, Andrea M.presenter [email protected](a)
Plants have long-distance root-to-shoot signaling mechanisms that generate integrative responses. Chemical or non-chemical signals are
further ways how physiological communication and integration occurs between roots and leaves for orchestration of adaptative responses.
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In this work, we performed a differential root proteomic analysis in order to elucidate the basis of complex biological processes such as
tolerance and adaptation to drought stress. Severe water deficit (leaf ψpd -3MPa) was imposed to contrasting C.canephora drought
response clones (120 tolerant and 109 sensible) and root differential expressed proteins protein were analyzed by two-dimensional gel
electrophoresis and sequenced by MALDI-TOF-TOF. Data mining was done in NCBI non-redundant (Viridiplantae) protein database and EST
Coffea bank. Tolerant clone appeared to postpone tissue dehydration to a remarkable greater extent than sensitive clone. Stomata
sensitivity was lower in sensitive clone which can be linked to differences observed in net photosynthetic rate and dehydration. Comparative
proteome analysis revealed more than 250 protein spots reproducibly detected, 81 presented differential expression under drought stress
conditions. Among them proteins related to gibberelin and ethylene biosynthetic pathway suggesting differential control of root architecture;
dehydrin related to maintenance of osmotic potential; aldehyde dehydrogenase, mitochondrial processing peptidase, fructokinase and UDPglucose pyrophosphorylase involved in regulation of carbohydrate metabolism; aldo-keto reductase, monodehydroascorbate reductase
related to detoxification. This study provides a dynamic view of root contribution on drought stress response in coffee plants. Financial
support: Brazilian coffee consortium.
(a) Departamento de Biologia Vegetal, Universidade Federal de Vicosa, Vicosa MG, Brazil. (b) Laboratorio de Toxinologia, Fundacao Oswaldo
Cruz (FIOCRUZ), Rio de Janeiro RJ, Brazil. (c) Departamento de Bioquimica e Biologia Molecular, Universidade Federal de Vicosa, Vicosa
MG, Brazil.
P10051 Analysis of cold acclimation ability in Petunia spp.
Walworth, Aaron E.-presenter [email protected](a)
Warner, Ryan M. (a)
Freezing tolerance of many plant species increases following exposure to low, non-freezing temperatures, a process termed cold
acclimation. Within the plant family Solanaceae, species vary widely in cold acclimation ability. Petunia ( Petunia x hybrida) can cold
acclimate; while chilling-sensitive tomato cannot cold acclimate. In the model plant species Arabidopsis thaliana, the CBF family of
transcriptional activators plays an important role in cold acclimation. The objectives of this work were to determine whether natural
variation in cold acclimation ability exists among Petunia spp. and to determine whether heterologous expression of CBF genes improves
freezing tolerance of P. x hybrida. Freezing tolerance of petunia species P. exserta, P. integrifolia, P. axillaris and P. x hybrida ‗Mitchell‘ were
determined by measuring electrolyte leakage before and after a cold acclimation regime. Under non-acclimated conditions, all species had
similar EL50 values of ca. -2oC. Following a cold acclimation period, EL50 values varied significantly across species, ranging from -5oC for P.
exserta to -8oC for P. axillaris. P. x hybrida ‗Mitchell‘ plants were transformed with either AtCBF3 from Arabidopsis or the LeCBF1 from
tomato, both under the strong constitutive promoter CaMV 35S. Only a single transgenic line with high expression levels of AtCBF3 showed
an increase in constitutive freezing tolerance, while acclimated tolerance was similar to wild-type. None of the LeCBF1-expressing lines
showed any significant improvements in constitutive or acclimated freezing tolerance. These results suggest that CBF-independent pathways
play an important role in cold acclimation of petunia.
(a) Michigan State University, Department of Horticulture
P10052 Specific Changes in Leaf Characteristics of Two Bean Genotypes as Affected by Differential Zinc Availability
Hacisalihoglu, Gokhan-presenter [email protected](a)
Lampley, Aja (a)
http://www.innoplants.com
Understanding how plants respond to low Zinc (Zn) is important, as Zn deficiency is a major factor affecting crop productivity throughout
the world. Selection and breeding of plants for Zn efficiency, ability to maintain reasonable yield under Zn deficiency, is a useful approach to
increase production and quality on low Zn soils. Hydroponic experiments were conducted to investigate the responses of two bean cultivars
(Phaseolus vulgaris L. cvs. Calima and Jamapa) to differential Zn conditions. Bean seedlings were grown in chelate buffer nutrient solution
and exposed to low and sufficient Zn conditions. Plant height, taproot length, final shoot and root fresh weight, leaf symptoms, shoot and
root [Zn], and chlorophyll content were recorded for up to 28 days. Leaves of different sizes were collected from plants and leaf area was
determined by a leaf area meter (CI-202, CID). The results showed that shoot and leaves are most likely key sites of Zn efficiency trait in
bean. Furthermore, the results also showed that chlorophyll levels (SPAD) and leaf area may be useful tools that correlated with Zn
efficiency in common bean. Overall, cv. Calima was highly resistant, while cv. Jamapa was very susceptible to Zn stress. The susceptible cv.
Jamapa displayed a decreased shoot length, taproot length, chlorophyll content, and leaf area under low Zn conditions-. This study
demonstrated that leaf area permitted the discrimination of Zn-efficient and Zn-inefficient bean lines. Therefore, measurement of leaf area
may provide a useful indirect criterion for screening of Zn efficiency in bean. The current status of this project and further detailed results
will be presented.
(a) Florida AM University
P10053 Investigation of AP2/ERF Genes Involved in Abiotic Stress Signal Transduction in Arabidopsis and Rice
Seok, Hye-Yeon -presenter [email protected](a)
Park, Hee-Yeon (a)
Lee, Choon-Hwan (a)
An, Gynheung (b)
Moon,
Yong-Hwan (a)
Plants often encounter hypoxic or anoxic environments when they are submerged by heavy rain or ensuing flood. The deleterious effects
associated with hypoxia are responsible for the slowed growth and reduced yield of many agriculturally important crops in the event of
flooding. In this study, we selected two rice AP2/ERF genes up-regulated by low oxygen from previous microarray data. RT-PCR results and
analysis of OsAP2/ERF promoter::GUS transgenic plants confirmed that OsAP2/ERF1 and OsAP2/ERF2 are up-regulated under low oxygen
stress. Arabidopsis homologues of OsAP2/ERF1 and OsAP2/ERF2, AtAP2/ERF1 and AtAP2/ERF2, respectively, were isolated using BlastP
analysis. AtAP2/ERF1 was highly up-regulated under low oxygen stress whereas AtAP2/ERF2 was slightly up-regulated. Interestingly,
AtAP2/ERF1 also up-regulated under other stress conditions such as NaCl, mannitol, ABA, and MV. AtAP2/ERF1 and AtAP2/ERF2
overexpression transgenic plants were more resistant to abiotic stresses such as NaCl, mannitol, MV, and flooding than wild-type plants, and
T-DNA tagging mutant of AtAP2/ERF2 was more sensitive to osmotic stresses. Because AtAP2/ERF1 is highly induced under osmotic-,
oxidative-, and hypoxia-stresses, we are investigating cis-acting elements of AtAP2/ERF1 promoter responsible for stress responses using
AtAP2/ERF1 promoter deletions::GUS transgenic plants. Our results suggest that both AP2/ERF1 and AP2/ERF2 in rice and Arabidopsis
might play important roles in abiotic stress signal transduction.
(a) Pusan National University, Busan, Korea (b) Pohang University of Science and Technology, Pohang, Korea
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P10054 Arabidopsis MAPK, MAPKK, MAPKKK Genes Involved in Osmotic Stress Signal Transduction
Kim, Jae-Min (a)
Park, Hee-Yeon-presenter [email protected](a)
Huan, Le Dinh (a)
Moon, Yong-Hwan (a)
Mitogen-activated protein kinases (MAPKs) are widely involved in cellular responses to extracellular stimuli. MAPK signalling pathways
regulate cell growth, death, differentiation, cell cycle, and stress responses. MAPKs are activated by phosphorylation through protein
phosphorylation cascades including MAPKKKs and MAPKKs. And then, MAPKs finally activate transcription factors to activate specific
response genes. In this study, to identify and characterize MAPKKKs, MAPKKs, and MAPKs involved in osmotic stress signal transduction, we
investigated osmotic stress response of 21 MAPKKKs, 10 MAPKKs, and 20 MAPKs in Arabidopsis. First, we have studied responses of
mutants of the MAPKKK, MAPKK, and MAPK genes to osmotic stresses such as NaCl, MV, and drought, and then selected some mutants that
showed sensitive or resistant response to the stresses. We have analyzed the expression patterns of stress-response genes such as NCED3,
RD29A, and Rab18 in those selected mutants. Also, we analyzed the expression patterns of the selected genes under stress conditions using
RT-PCR analysis. Now, we are studying biological functions of five selected MAPK, MAPKK, MAPKKK genes in abiotic stress signal
transduction.
(a) Department of Biological Sciences, Pusan National University, Busan, Korea
P10055 Investigation of Mutants with Altered NCED3 Expression under Abiotic Stress in Arabidopsis
Woo, Dong-Hyuk (a)
Park, Hee-Yeon -presenter [email protected](a)
Kang, In-Soon (b)
Moon, Byoung Yong (b)
Lee,
Chin-Bum (c)
Moon, Yong-Hwan (a)
A plant hormone, abscisic acid (ABA), is known as the main signal transducer that confers abiotic stress tolerance to plants. In this study, to
identify upstream genes regulating ABA biosynthesis involved in abiotic stress signal transduction, Arabidopsis mutants with changed
promoter activity of 9-cis-epoxycarotenoid dioxygenase 3 (NCED3), a key gene in ABA biosynthesis, were identified and characterized. The
mutants were classified into two groups such as henc (for high expression of NCED3) and lenc (for low expression of NCED3) that showed
higher and lower NCED3 promoter activity, respectively, after dehydration treatment. One of lenc group mutants, lenc1, and one of henc
group mutants, henc1 were selected for further analysis. RT-PCR analysis indicated that the transcript level of NCED3 gene in lenc1 was
lower, but in henc1 was higher under dehydration, NaCl and ABA treatments as well as normal condition. Furthermore, the transcript levels
of stress-responsive genes such as RD29A, RAB18, COR15A and RD22 were lower in lenc1 but higher in henc1 than in WT under nonstressful condition. lenc1 mutant was sensitive to LiCl and showed different responses to MV depending on developmental stages. On the
other hand, henc1 mutant was resistant to NaCl and its root elongation was more suppressed by KCl treatment. Analysis of membrane lipids
and fatty acid compositions showed that both mutants had no differences in the composition of membrane lipids except PE and that fatty
acid compositions of SQDG were altered most remarkably as compared to WT. Our results suggest that LENC1 and HENC1 might act as a
positive regulator and a negative regulator, respectively, in the regulation of NCED3 gene expression under osmotic stresses.
(a) Department of Biological Sciences, Pusan National University, Busan 609-735, Korea (b) Department of Biotechnology and Biomedical
Sciences, Inje University, Gimhae, Gyeongnam 621-749, Korea (c) Department of Molecular Biology, Dong-eui University, Busan 614-714,
Korea
P10056 Purification and identification of anti-ice nucleation substances in deep supercooling xylem parenchyma cells of
katsura tree (Cercidiphyllum japonicum)
Kasuga, Jun-presenter [email protected](a)
Hashidoko, Yasuyuki (a)
Arakawa, Keita (a)
Fujikawa, Seizo (a)
Xylem parenchyma cells (XPCs) in boreal hardwood species adapt to subfreezing temperatures by deep supercooling. Until recently, the
mechanism of deep supercooling has been thought to be developed only by isolation of protoplasts from extracellular ice crystals due to the
specific property of cell walls in XPCs. However, our recent study suggested the involvement of intracellular substances to the mechanism of
deep supercooling. We found that crude methanol extracts from xylem of katsura tree exhibited anti-ice nucleation activity to promote
supercooling of water. Thus, we attempted to purify and identify the causative substances. We separated crude extracts by liquid-liquid
extraction (ethyl acetate / water). Ethyl acetate fraction with higher activity was further separated by silica gel column chromatography into
17 fractions. Among these 17 fractions, all of them showed anti-ice nucleation activity in the range from 1.4C to 4.8C. These results
indicated the existence of diverse kinds of anti-ice nucleation substances in the crude extracts. We chose one fraction with the highest
activity among 17 fractions and could isolate four anti-ice nucleation substances from the fraction by HPLC. These substances were
identified as flavonol glycosides on the basis of UV, mass and NMR spectra. Among these substances, kaempferol-7-O-β-glucoside showed
the highest anti-ice nucleation activity (9.0C) than any other previously reported substances. The accumulation of flavonoids in cytoplasms
of XPCs was shown by confocal laser scanning microscopy. These results suggest that flavonol glycosides and many other anti-ice
nucleation substances may involve in the mechanism of deep supercooling in XPCs.
(a) Graduate School of Agriculture, Hokkaido University
P10057 INDENTIFICATION OF STRESS RELATED PROTEINS WITH ALTERED EXPRESSION IN TRANSGENIC ARABIDOPSIS
OVEREXPRESING THE CpMYB10 TRANSCRIPTION FACTOR GENE FROM THE RESURRECTION PLANT Craterostigma
plantagineum.
Villalobos, Miguel A.-presenter [email protected](a)
Iturriaga, Gabriel (b)
Arroyo, Analilia (a)
http://www.cibatlaxcala.ipn.mx
The CpMYB10 gene from the resurrection plant C. plantagineum was previously isolated and characterized. This gene was demonstrated to
be transcriptionally regulated by abscisic acid (ABA) and abiotic stress. Heterologous/ectopic expression of CpMYB10 enhances drought and
salinity tolerance in transgenic Arabidopsis, and results in a more abundant root system and phenotypes of sugar insensitivity, ABA
hypersensitivity and altered gene expression of drought responsive genes. In order to identify proteins differentially expressed in response
to CpMYB10, a proteomic analysis was performed from a representative CpMYB10 constitutive overexpressor transgenic line (35S-CpMYB10)
and a control line transformed with the binary vector. Proteomes were compared using ABA treated and untreated plants. Several
differentially expressed proteins in response to ABA were identified by MALDI-ToF. Some of the identified proteins show a clear relation with
environmental stress responses. Interestingly some proteins present in control plants treated with ABA are also present in untreated
CpMYB10 constitutive overexpressor transgenic plants. This suggests that under control growth conditions, CpMYB10 overexpression
induces/derepresses the expression of some proteins in response to stress in transgenic plants. It is likely that even under non-stressing
conditions, CpMYB10 overexpression turns ON part of the signal transduction pathway in response to stress. We thank SIP-IPN and
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CONACYT for grant supports
(a) Centro de Investigacion en Biotecnologia Aplicada-IPN (b) Centro de Investigacion en Biotecnologia-UAEM
P10058 ISOLATION AND CHARACTERIZATION OF CuZnsod GENE FROM WOUNDED AVOCADO FRUIT.
Garcia-Pineda, Ernesto (a)
Arreola-Cortes , Araceli-presenter [email protected](a)
Lozoya-Gloria, Edmundo (b)
In plants exposure to photoinhibitory light, ozone, wounding or other environmental conditions that cause oxidative stress can increase O2levels. Superoxide radicals are toxic; their toxicity has been attributed to the interaction with hydrogen peroxide to form highly reactive
hydroxyl radical (Desikan et al., 2005). These hydroxyl radicals can react with DNA, proteins, lipids and almost constituent of cell.
Superoxide dismutases (SOD) are metalloproteins that catalyze the dismutation of O2- to H2O2. The main function of the SOD is scavenge
O2- radicals generates from a number oxidative stresses. The plants have three SOD types FeSOD, MnSOD and CuZnSOD. CuZnSOD is
probably located in the extracellular space (Alscher et al., 2002); therefore it could be have a role during O2- stress production. Using
specific oligos to CuZnsod we have cloned a partial cDNA sod gen from avocado fruit treated by wounding by RT-PCR reaction. The
expression analysis in response to different stresses that increase O2- levels and copy number of this gene are in progress. Desikan R,
Hancock J, Neill S. 2005. Reactive oxygen species as signaling molecules. In: Antioxidants and reactive oxygen species in plants (ed N.
Smirnoff), Blacwell Publishing, Oxford, UK. Alscher RG, Erturk N, Heath LS. 2002. Role of superoxide dismutase (SODs) in controlling
oxidative stress in plants. J. Exp. Bot. 53:1331-1341.
(a) UMSNH, Instituto de Investigaciones Quimico Biologicas (b) Cinvestav-IPN, Campus Irapuato, Dept. de Ingenieria Genetica.
P10059 A model for prediction of heat stability of photosynthetic membranes a
Ristic, Zoran-presenter [email protected](a)
Bukovnik, Urska (b)
Prasad, Vara P.V. (b)
West, Mark (a)
A previous study has revealed a positive correlation between heat-induced damage to photosynthetic membranes (thylakoid membranes)
and chlorophyll loss [Ristic et al. (2007) Crop Science 47: 2067-2073]. In this study, we exploited this correlation and developed a model for
prediction of thermal damage to thylakoids. Prediction is based on estimation of the ratio of constant chlorophyll a fluorescence (O) and the
peak of variable fluorescence (P) (O/P) using chlorophyll content as a predictor. The model was developed using 12 cultivars of hexaploid
winter wheat (Triticum aestivum). The model was tested in six genotypes of hexaploid wheat, 25 genotypes of tetraploid wheat ( T.
turgidum), and 20 genotypes of maize (Zea mays). Predictive ability was assessed by analyzing the relationship between the predicted and
measured O/P and by comparing prediction error to model error. The model adequately predicted O/P and thereby the heat stability of
thylakoid membranes in all genotype groups with high coefficients of determination (r2 > 0.80). The model could be used as an easy and
inexpensive means for detection of the structural and functional state of photosynthetic membranes in wheat and maize, and possibly other
crops, in hot environments. aCrop Science (2008, in press)
(a) USDA - ARS, Plant Science and Entomology Research Unit (b) Department of Agronomy, Kansas State University
P10060 Functional analysis of the 1-Cys peroxiredoxin from buckwheat (Fagopyrum esculentum Moench).
Ueda, Takashi-presenter [email protected](a)
Our research explores the possibility of enhancing the capability of the plants to tolerate abiotic stress such as desiccation, high salinity,
unfavorable temperatures, and UV-irradiation through genetic manipulation of gene encoding an antioxidant enzyme, 1-Cys peroxiredoxin.
1-Cys peroxiredoxins belong to a recently discovered class of thiol-specific antioxidants that are evolutionarily conserved among a wide
variety of organisms, ranging from Archaebacteria to humans. In many angiosperm plant species, 1-Cys peroxiredoxins are expressed
during seed maturation, and they are thought to play a role in the desiccation tolerance of the embryo. In some angiosperm species,
particularly those that can tolerate repeated desiccation conditions, 1-Cys peroxiredoxin antioxidant enzymes have also been shown to be
expressed in vegetative tissues and seem to be involved in vegetative desiccation tolerance. In our transgenic studies in Arabidopsis, we
have demonstrated that ectopic expression of buckwheat (Fagopyrum esculentum) 1-Cys peroxiredoxin was effective in increasing the
stress tolerance of the plants.
(a) Florida Gulf Coast University
P10061 Expression of Rubisco activase in wheat, maize, and Arabidopsis thaliana under heat stress conditions
Ristic, Zoran-presenter [email protected](a)
Momcilovic, Ivana (b)
Bukovnik, Urska (b)
DeRidder, Benjamin P. (c)
Rubisco activase (RA) is a nuclear-encoded soluble chloroplast protein that regulates the activity of Rubisco. In most species studied, RA is
found in two isoforms, the longer α (43 to 46 kD) and the shorter β (41 to 42 kD). Using immunoblotting, in this study we investigated the
effect of heat stress on the expression of RA in several genotypes of wheat (Triticum aestivum) and maize (Zea mays), and one genotype of
Arabidopsis thaliana. Immunoblots prepared with leaf protein extracts from control plants showed three RA cross-reacting bands in wheat
and two RA cross-reacting bands in maize and Arabidopsis. The molecular mass of the observed bands was in the range between 40 and 46
kD. Heat stress affected the expression of RA in wheat and maize but not in Arabidopsis. In wheat, heat stress (36oC) increased the
amounts of RA. In maize, heat stress (45oC) did not affect the existing RA isoforms (40 and 43 kD) but induced accumulation of a new
putative RA of 46 kD. Interestingly, the new putative 46 kD RA was not seen in a genotype of maize that shows an exceptional sensitivity to
heat stress. The results suggest that in some species modulation of the expression of RA may be related to the plant ability to tolerate heat
stress.
(a) USDA - ARS, Plant Science and Entomology Research Unit (b) Department of Agronomy, Kansas State University (c) Department of
Biology, Grinnell College
P10062 A role of Calcium Dependent Protein Kinase 32 (CPK32) from Arabidopsis in Stress Signaling
Karve, Rucha (a)
Cheng, Shu Hua (a)
Moore, Brandon d-presenter [email protected](a)
Calcium-dependent protein kinases (CPKs) are major plant Ca2+ sensors, many of which have roles in plant stress responses. The
Arabidopsis genome encodes 34 CPK isoforms. Here we report some characterization of the CPK32 gene function. Analysis of transgenic
plants expressing pCPK32-GUS showed that CPK32 is highly expressed in roots, pollen and embryo, as well as the root-hypocotyl junction,
leaf hydathodes, and the abscission zone of mature siliques. Plants treated with salt, ABA, osmotic stress (PEG), or wounding had increased
GUS staining. By RT-PCR, CPK32 transcript was induced up to about 5-fold in WT plants after stress treatment. A CPK32 knockout
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line(cpk32-1) was identified from GABI-Kat insertional mutants and was tested with a CPK32 overexpression line in different germination
and seedling growth assays. cpk32-1 seeds are hypersensitive to germination and to seedling growth with salt, ABA or osmotic stress, while
CPK32 OE plants are relatively insensitive. We also showed that in transient expression assays using maize leaf protoplasts, CPK32-GFP is
localized only to the plasma membrane. This localization requires protein myristoylation and palmitoylation of key residues at the Nterminus (G2, C4, and C5). Nonetheless, upon ABA treatment at concentrations of 10-50 μM, CPK32-GFP begins to internalize in 5-15 min
and moves into the nucleus. Our data support the possibility that CPK32 is a key factor that mediates tissue-specific plant stress responses
through ABA signaling.
(a) Clemson University
P10063 Ozone Exposure May Accelerate Spread of Glyphosate Resistance in Horseweed (Conyza canadensis)
Grantz, David A-presenter [email protected](a)
Shrestha, Anil (b)
Vu, HaI-Bang (a)
Glyphosate resistance (GR) in California horseweed (Conyza Canadensis) was discovered in 2005. By 2008, the glyphosate-sensitive (GS)
biotype was rare in the eastern San Joaquin Valley where plants are regularly exposed to glyphosate and to high levels of ambient ozone
(O3). GR is more robust than GS in the absence of ozone and this advantage is reduced but not eliminated at elevated O3. In the presence
of field rate (1.0 x) glyphosate, GR and GS differed in growth and injury, reflecting known sensitivities to glyphosate, but responded
similarly to O3 with no O3 x biotype interaction. O3 imposed a significant additive impact with glyphosate that enhanced competitiveness of
GR by reducing biomass to low but viable levels in GR, but to non-viable levels in GS, in the presence of the combined stressors. These
earlier data did not support a hypothesized genetic linkage between resistance to glyphosate and to O3, but did demonstrate that air
pollution accelerated fixation of resistance. Here we extend these experiments to a range of non-lethal glyphosate concentrations crossed
with the same range of O3 concentrations. We find significant interaction between glyphosate and O3 for leaf longevity and root to shoot
allocation in both biotypes but for most biomass parameters only in GS. In GS this was mostly due to growth suppression at low O3 by
glyphosate, which reduced further inhibition at elevated O3. These data suggest a mechanistic interaction between plant responses to these
two anthropogenic stressors, which in combination with the additive effect described above, may have rapid evolutionary significance. O3
air pollution may contribute to the spread of herbicide resistance.
(a) University of California Riverside; Kearney Agricultural Center (b) University of California IPM Project; Kearney Agricultural Center
P10064 The absence of alternative oxidase 1a in arabidopsis thaliana results in acute sensitivity to combined light and
drought stress
Giraud, Estelle J-presenter [email protected](a)
Ho, Lois HM (a)
Clifton, Rachel (a)
Carroll, Adam (a)
Estavillo,
Gonzalo (b)
Howell, Katharine A (a)
Pogson, Barry J (b)
Millar, Harvey (a)
Whelan, James (a)
Treatment of alternative oxidase 1a mutant plants (aox1a) with moderate light and drought resulted in a phenotypic difference compared to
Col-0, evidenced by a 10-fold increase in the accumulation of anthocyanins in leaves. Analysis of metabolite profiles revealed significant
changes upon treatment in aox1a plants typical of combined stress treatments and these were less pronounced or absent in Col-0 plants.
These changes were accompanied by alteration in the abundance of a variety of transcripts during the stress treatment, providing a
molecular fingerprint for the stress induced phenotype of aox1a plants, while no significant transcript changes were found during treatment
of Col-0 plants. Transcripts encoding proteins involved in the synthesis of anthocyanins, transcription factors, chloroplastic and
mitochondrial components changed in abundance, indicating that effects were not confined to mitochondria where the AOX1a protein is
located. Microarray and QRT PCR analysis revealed that transcripts typically induced upon stress treatment or involved in anti-oxidant
defence systems, especially chloroplast located anti-oxidant defence components, had altered basal levels in untreated aox1a plants,
suggesting a significant change in the basal equilibrium of signalling pathways that regulate these components. Taken together, these
results indicate aox1a plants have a greatly altered stress response, compared to Col 0 lines. Thus, AOX appears to play a central role in
defining the nature of the response.
(a) Centre of Excellence Plant Energy Biology University of Western Australia (b) Centre of Excellence Plant Energy Biology Australian
National University
P10065 Responses to Water Deficit Stress in Mexican Bryophytes Species Cultured Under in vitro Conditions.
Cervantes-Diaz, Fret-presenter [email protected](b,a)
Chamorro-Flores , Alejandra (b,a)
Morales-Eliosa , Elizabeth (a)
RiosMelendez, Selma (a)
Martinez, Jose L. (c)
Ruiz-Guerrero , Rosario (a)
Arroyo, Analilia (a)
Villalobos, Miguel A. (a)
http://www.cibatlaxcala.ipn.mx
Several resurrection plants had been used for the identification of genes involved in the molecular responses to drought. Craterostigma
plantagineum and Selaginella lepidophylla are classical resurrection models from which hundreds and even thousands of sequences had
been generated. In addition, some heterologous transgenic lines have been reported with enhanced drought tolerance as result of the overexpression of genes isolated from these highly drought tolerant plants. Thus, the use of genes isolated from resurrection plants is a
promising strategy to enhance drought tolerance in important crop cultures. Between lower plants, bryophytes are an interesting group of
plants with amazing drought tolerance capabilities. Unfortunately, the molecular mechanisms used by these resurrection plants to contend
with drought are poorly understood, and most of literature concerning this topic is very old. However, recently the moss Physcomitrella
patens and the hepatic Marchantia polymorpha arise as important models for the study of bryophytes at the molecular level: the genome
sequence for P. patens has been reported and both species are suitable for stable transformation. Mexico is own of an important diversity in
plants species. Particularly, we are interested in the identification of resurrection lower plants and in the analysis of their responses to water
deficit stress. In the present work we generated standardized axenic in vitro culture conditions generated for two mosses and two hepatic
species isolated from Mexican highlands around Popocatepetl, Matlacueyetl and Citlaltepetl volcanoes. A preliminary characterization of the
physiological and molecular responses of these species against to drought will be presented. We thank SIP-IPN and CONACYT for grant
supports.
(a) Centro de Investigacion en Biotecnologia Aplicada-IPN (b) Facultad de Agrobiologia-UAT (c) Centro de Investigaciones en Ciencias
Biologicas-UAT
P10066 Phenotypic and molecular characterization of two Selaginella species and salt grass in response to water deficit
stress.
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Castelan, Maria L.-presenter [email protected](a)
Aguila, Gerardo (a,b)
Roa, Norma A. (a,b)
Contreras , Jose L.
(c)
Iturriaga, Gabriel (d)
Ruiz-Guerrero, Rosario (a)
Villalobos, Miguel A. (a)
Arroyo, Analilia (a)
http://www.cibatlaxcala.ipn.mx
Abiotic factors limit growth and productivity of major crop species, thus there is special interest in establishing the physiological and genetic
bases of plant water deficit stress responses which have been widely studied in model plants. However, in nature some plant genera exist
typical from arid or even desert regions that are able to tolerate extreme stressing conditions, which make them ideal systems to study
water stress tolerance and use them as new models to understand water deficit stress. Thus, the objective of this study is the
characterization of new Mexican model plant species already adapted to extreme abiotic conditions. We have previously collected and
identified several native drought and salinity resistant plants from Mexican arid regions. From this collection, we selected Selaginella
lepidophylla, Selaginella sartorii and Distichlis spicata. S. lepidophylla has been widely studied at the physiological level and there are just a
few reported studies at the molecular level. In contrast, there are no physiological or molecular studies reported for S. sartorii except for 2
partial sequences. Additionally in the case of D. spicata, molecular studies are limited to 15 non-coding sequences corresponding principally
to microsatellites; however, many physiological responses to salinity stress have been reported under greenhouse and field conditions.
Here, we present a S. sartorii preliminar phenotypic characterization during hydration/dehydration cycles in comparison to S. lepidophylla.
We also present the establishment of axenic in vitro conditions for D. spicata germination as well as osmotic and salinity responses during
germination. Expression of abiotic stress related genes will also be presented. We thank SIP-IPN and CONACYT for Grant supports
(a) Centro de Investigacion en Biotecnologia Aplicada-IPN (b) Facultad de Ing. Quimica-UPT (c) Herbario-BUAP (d) Centro de Investigacion
en Biotecnologia-UAEM
P10067 The role of Hsa32 in basal thermotolerance in Arabidopsis
Wu, Szu-hsien-presenter [email protected](a)
Chi, Wen-tzu (a)
Charng, Yee-yung (a)
Hsa32 is a novel heat-shock-induced protein mainly found in land plants. Arabidopsis T-DNA knockout (KO) mutant of Hsa32 has severe
defect in acquired thermotolerance after long but not short recovery following an acclimation treatment. Here, we show that AtHsa32 is also
required for basal thermotolerance (BT). The Hsa32 KO plants died after a short and severe heat shock (HS) challenge while the wild type
remained alive. Since the level of Hsa32 protein in the wild-type seedlings was not detectable by western blot under normal condition or
during the heat shock treatment, it raised a question regarding the action mode of Hsa32 on BT. Western blot analysis showed that Hsa32,
as well as Hsp101 and sHsp-CI, was dramatically induced one day after the severe HS, suggesting that the post-HS induction of Hsa32 as
well as other Hsps is essential if not sufficient for BT. Interestingly, disruption of Hsa32 dramatically retarded the post-HS induction of other
Hsps, suggesting that Hsa32 plays a role in regulating post-HS response. Similar situation was observed in the Hsp101 KO line, which
suggests a complex interplay between Hsa32 and Hsp101 in BT. Consistenly, inhibiting the synthesis of Hsps by actinomycin D or
cycloheximide during recovery diminished the BT level of the wild-type plants. In addition, we show that HsfA1a/1b was required for BT
based on the survival rate assay. Suppression of post-HS induction of Hsps was also observed in the double KO mutant of the transcription
factor genes, suggesting that HsfA1a/1b play an important role in transcription regulation of the post-HS response. Taken together, we
conclude that basal thermotolerance requires the timely induction of Hsp genes during recovery which are under the control of HsfA1a/b.
(a) Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
P10068 Salinity stress adaptation in tolerant cultivars of rice (Oryza sativa indica) in comparison to sensitive one
Rai, Vandna-presenter [email protected](a)
Singh, Nagendra K (b)
We used two rice cultivars with contrasting salt and drought tolerance for global gene expression study. Upto 209 and 283 probe sets upand down-regulated in salt sensitive genotype. Same as CSR-27 283 and 191 probe sets were up- and down-regulated. There are 58 probe
sets which were commonly up-regulated in both the cultivars and salt stress condition and only six probe sets that were down regulated in
both the cultivars. The cultivar MI-48 is supposed to be drought tolerant while CSR-27 is drought sensitive. It was found that 230 probes
were down and 248 gene probes were up-regulated in CSR-27 (a drought sensitive) when plants were exposed to drought condition among
which 47 and 82 gene probe sets were commonly down and up-regulated in control and drought stressed samples. Genes related to
drought tolerance, photo system I stabilization, photosynthesis, light harvesting in photo system I, chlorophyll catabolic process, mRNA
splicing, lipid metabolic process and transcription are some of the biological process sodium;dicaboxylate symporter activity, ATPase activity
and transcription factors activity are molecular function genes which are up regulated in salinity stress while response to salt stress, calcium
ion homeostasis, MAP/ERK kinase activity are some genes down-regulated in presence of salt. In this study we attempted to clarify the
differences and adaptations of tolerant cultivars by phenotyping, physiological, biochemical and gene expression studies in rice plant.
(a) National Research Centre on Plant Biotechnology (b) National Research Centre on Plant Biotechnology, IARI, New Delhi
P10069 Phosphate deficiency reduces starch breakdown in beans (Phaseolus vulgaris L.)
Bernal, Lilia Angelica-presenter [email protected](a)
Martinez, Eleazar (a)
Phosphorus is essential for living organisms because it is a key component in metabolic processes. In response to three weeks of phosphate
(Pi) deficiency, bean plants (Phaseolus vulgaris L.) show several biochemical and molecular changes like the starch accumulation in mature
leaves. Under Pi deprivation starch breakdown is reduced although the β-amylase activity increased. The characteristics of starch, as well as
the association of proteins to starch granules, are affected by Pi deficiency and both contribute to reduce its hydrolysis by β-amylase.
Oxidative stress is often considered as a general component of biotic and abiotic stresses and our results suggest that an increment in
oxidizing conditions may prevail in cells of plants with Pi deficiency. On the other hand, β-amylase is regulated by a redox state and its
activity is largely reduced in an oxidized state. Therefore Pi starvation predicts a less favourable condition for β-amylase activity. The effect
of redox state over β-amylase activity was investigated. We observed that in the presence of starch, β-amylase is not inhibited by an
oxidized environment. In spite of the redox conditions that were used, starch from plants grown in Pi starvation, remained less susceptible
to β-amylase degradation. Finally, our resulting data suggest that starch can influence redox conditions; since it can contribute to produce a
less oxidized environment; under Pi deficiency, starch might help to protect the activity of different enzymes, such as the β-amylase. By the
data, we can conclude that the low rate of degradation observed in starch produced by plants cultivated under Pi deficiency, is mainly due
to the characteristics of the starch produced under this condition.
(a) Universidad Nacional Autonoma de Mexico
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P10070 Trehalase Gene Silencing in Plants: Hidric Stress Tolerance and Biomass Increase
Gamez-Escobedo, Anali-presenter [email protected](a)
Villanueva Olivo, Arnulfo (b)
Franco-Arias, Eduardo (b)
CabreraPonce, Jose Luis (c)
Hernandez-Luna, Carlos (b)
Herrera-Estrella, Luis (c)
Adame-Rodriguez, Juan Manuel (b)
Montes de OcaLuna, Roberto (b)
From long time ago, drought and high temperature stress tolerance have been two goals for plant breeders, since these are two of the
major problems to which plants face up in fields. Recently, some strategies have taken off from nature and placed them in crops by genetic
engineering. One of these strategies is the over expression of enzymes related to trehalose metabolism, in order to synthesize this
disaccharide in the plant tissue. However, a no significant increase of this sugar was reported due to endogenous hydrolytic activity by
trehalase enzyme. An antisense RNA transgenesis protocol was proved on tobacco plants, using a trehalose sequence from alfalfa. These
plants showed a fast and enhanced growth in vitro and were also capable of grow adequately in the absence of any source of available
carbon, compared to their wild and transgenic controls. In addition, they had the ability to accumulate glucose when it was provided at
media. This is maybe due to an enhanced photosynthetic activity, as it has been reported when trehalose-6-phosphate synthase (TPS) is
over expressed in plants, allowing them a better atmospheric CO2 fixation. Like those TPS-plants, trehalase-antisense plants acquired
osmotic stress tolerance induced by PEG in vitro and showed up to 10% of increase in germination and up to 60% of increase in height.
Besides this strategy could provide an approach to generate crops with low water demand also could be followed to reach a better biomass
production without a high requirement of watering as a way to improve bioenergy generation in desertic regions.
(a) Universidad Autonoma de Coahuila (b) Universidad Autonoma de Nuevo Leon (c) Centro de Investigaciones y Estudios Avanzados
Session P11 – Water Relations
P11001 Genetic Diversity in Sorghum Transpiration Efficiency
Xin, Zhanguo-presenter [email protected](a)
Aiken, Rob (b)
Sorghum is the fifth most important grain crop and is becoming increasingly important as a biofuel feedstock due to its superior tolerance to
water deficit stress. Sorghum is commonly grown under rain-fed conditions in the Southern Plains and other semi-arid regions in the world.
Thus, its production is strongly affected by the availability of soil water during growing season. Enhancing transpiration efficiency (TE),
defined as biomass accumulation per unit water transpired, may be an effective approach to increase sorghum yield in arid and semi-arid
regions under no or limited irrigation. A collection of 406 sorghum accessions were screened for variation in TE. Twenty-five lines were
selected to conduct re-confirmation studies at two locations that have different experimental conditions and water regimes. Significant
variation in TE was identified at both locations. While most lines displayed different rank in TE at the two locations, several lines with
consistently greater or less TE were identified. TE based on biomass production was strongly correlated with increased biomass
accumulation rather than reduced transpiration. Gas-exchange analysis of eight selected lines indicated that decreased internal CO2
concentration and enhanced PEP carboxylase activity may contribute to the increase in TE. The results indicate that considerable genetic
variation in TE exists in sorghum germplasm collection and that TE is strongly influenced by environment.
(a) Agriculture Research Service, USDA (b) K-State NWREC
P11002 Water permeability of apple protoplasts
Hertog, Maarten LATM-presenter [email protected](a)
Oey, Mailin (a)
Verboven, Pieter (a)
Nicolai, Bart (a)
Texture is one of the primary quality attributes of fruit and vegetables. It is determined by the mechanical properties of the tissue which are
on their turn determined by various microscopic cellular and histological features, such as cell size, amount of intercellular space,
mechanical properties of the cell wall and middle lamella, and turgor pressure. Knowledge of the relationship between tissue level (macro
scale) deformations and cellular (micro scale) properties is a prerequisite for the development of mathematical models predicting
mechanical behaviour of plant tissue and eventually intact fruits. Within the frame work of such a multi-scale modelling approach water
permeability of apple protoplasts was measured by monitoring volume changes of isolated protoplast exposed to osmotic treatments.
Protoplast were exposed to either hypertonic or hypotonic solutions (or a combination of these) meanwhile recording the volume changes
under a stereomicroscope using a CCD camera. Afterwards, the images were analysed to determine the change in diameter of the
protoplasts over time. The volume change was modelled based on the volumetric flux of water through the protoplast membrane driven by
the concentration gradient over the membrane. By analyzing the experimental data with the developed model water permeability could be
estimated. Values were obtained for protoplast isolated from either fresh or stored apples. No significant differences were observed
between fresh and stored apple protoplasts. This indicates that the extensive ripening related softening occurring during normal storage (so
not senescence breakdown) is not affecting cell membrane integrity in terms of its water permeability.
(a) K.U.Leuven
P11003 Stimulated photosynthesis alters sugar and amino-acid profiles, lowers osmotic potential and improves water
status of soybean leaves under free-air CO2 enrichment
Leakey, Andrew DB (a,b)
Sun, Jindong-presenter [email protected](b)
Markelz, Cody RJ (a,b)
Ort, Donald R (c,b)
Elevated [CO 2] reduces the stomatal conductance, transpiration and soil moisture depletion of C3 and C4 species, thereby delaying the
onset of drought stress. Elevated CO2 may provide additional advantage to C3 species by enhancing drought tolerance via stimulated
photosynthesis supporting greater osmo-regulation and leaf water status. This hypothesis was tested in a genomic, metabolomic and
physiological investigation of soybean at the SOYbean Free-Air Concentration Enrichment (SOYFACE) fieldsite in Illinois. Soybean was grown
in four plots at ambient [CO2] (~380 ppm) and four plots at elevated [CO2] (~550 ppm), from sowing until harvest. The 2006 growing
season was unusual because frequent, large rainfall events kept the soil moisture content near field capacity for the entire field season and
prevented differences in transpiration from altering rates of soil moisture depletion between the ambient and elevated [CO2] plots. While
this meant that drought stress was not occurring in either treatment, leaf contents of pinitol, sucrose, glucose, fructose and free amino
acids were all greater at elevated [CO2]. On average across 4 development stages, the pool sizes of these metabolites generated osmotic
potentials of -0.85 MPa at ambient [CO2] and -1.20 MPa at elevated [CO2]. This corresponded with average measured leaf osmotic
potential of -1.47 MPa at ambient [CO2] and -1.82 MPa at elevated [CO2], as well as greater leaf turgor. The altered leaf osmotic status
was associated with greater photosynthesis and greater abundance of transcripts encoding components of carbohydrate and amino acid
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metabolism. The overall response constitutes a direct effect of elevated [CO2] on leaf water status and a second mechanism ameliorating
drought stress of C3 plants at elevated [CO2].
(a) 1Department of Plant Biology, University of Illinois at Urbana-Champaign (b) 2Institute for Genomic Biology, University of Illinois at
Urbana-Champaign (c) 3Photosynthesis Research Unit, USDA-ARS, Urbana
P11004 Synthesis and mobilization of carbohydrate in xylem tissue of boll developing cotton during water deficiency
Roper, Becky J-presenter [email protected](a)
Holaday, AS (a)
Normally, cotton (Gossypium hirsutum) xylem serves as a strong sink for the storage of starch. The aim of this study was to determine
whether water deficit during reproductive growth could potentially reduce the sink strength of the xylem, making it a source of
carbohydrate that could be used for osmotic adjustment and/or for fruit and seed growth when photosynthesis was minimal. During water
deficiency, reproductive organs would likely be better competitors than xylem for soluble sugars, such as sucrose, the major translocated
sugar in cotton. One might expect that the activities of key enzymes associated with starch storage metabolism in the xylem would decline
concomitant with an increase in sucrose synthesizing enzymes during drought. We subjected wild-type (wt) cotton (cv. coker-312) and
cotton overproducing sucrose phosphate synthase (SPS+) to slowly-developing water deficiency. Extractible enzyme activity of starch
synthesizing (sucrose synthase & ADP-glucose pyrophosphorylase) and starch mobilizing (SPS & amylase) enzymes are being analyzed and
compared to carbohydrate content of xylem tissue. We noted a strong decrease in the extractable activity of sucrose synthase, an enzyme
determining sink strength, in the xylem of both genotypes, whereas SPS activity increased in the wt. Also, sucrose content of the xylem
increased in the wt. The SPS+ plants did not show an enhanced response over wt in preliminary analyses. Our preliminary data support the
idea that sink strength of the xylem of cotton declines with water deficit stress to the extent that it may serve as a source of soluble sugars
for reproductive sinks.
(a) Department of Biological Sciences, TTU
P11005 Stimulated photosynthesis alters sugar and amino-acid profiles, lowers osmotic potential and improves water
status of soybean leaves under free-air CO2
Sun, Jindong-presenter [email protected](a,b)
Leakey, Andrew DB (a,b)
Markelz, Cody RJ (b)
Ort, Donald R (a,c)
Elevated [CO2] reduces the stomatal conductance, transpiration and soil moisture depletion of C3 and C4 species, thereby delaying the
onset of drought stress. Elevated CO2 may provide additional advantage to C3 species by enhancing drought tolerance via stimulated
photosynthesis supporting greater osmo-regulation and leaf water status. This hypothesis was tested in a genomic, metabolomic and
physiological investigation of soybean at the SOYbean Free-Air Concentration Enrichment (SOYFACE) field site in Illinois. Soybean was
grown in four plots at ambient [CO2] (~370 ppm) and four plots at elevated [CO2] (~550 ppm), from sowing until harvest. The 2006
growing season was unusual because frequent, large rainfall events kept the soil moisture content near field capacity for the entire field
season and prevented differences in transpiration from altering rates of soil moisture depletion between the ambient and elevated [CO2]
plots. While this meant that drought stress was not occurring in either treatment, leaf contents of pinitol, sucrose, glucose, fructose and
free amino acids were all greater at elevated [CO2]. On average across 4 development stages, the pool sizes of these metabolites
generated osmotic potentials of -0.85 MPa at ambient [CO2] and -1.20 MPa at elevated [CO2]. This corresponded with average measured
leaf osmotic potential of -1.47 MPa at ambient [CO2] and -1.82 MPa at elevated [CO2], as well as greater leaf turgor. The altered leaf
osmotic status was associated with greater photosynthesis and greater abundance of transcripts encoding components of carbohydrate and
amino acid metabolism. The overall response constitutes a direct effect of elevated [CO2] on leaf water status and a second mechanism
ameliorating drought stress of C3 plants at elevated [CO2].
(a) Institute for Genomic Biology, UIUC, Urbana, IL 61801 (b) Department of Plant Biology, UIUC, Urbana, IL 61801 (c) Photosynthesis
Research Unit, USDA-ARS, Urbana, IL 61801
P11006 Desiccation tolerance of protoplasts isolated from cultured cells of Marchantia polymorpha.
Sayama, Hideaki (a)
Hatanaka, Rie (a)
Sugawara, Yasutake-presenter [email protected](a)
Plant cells are capable of developing tolerance to various stresses when cultured under suitable conditions. Tissue culture is a promising
system for study on the cellular mechanisms of desiccation tolerance of plants. We previously showed that cultured cells of M. polymorpha
developed very high desiccation tolerance when cultured in media with 0.25 M sucrose and then 0.5 M sucrose. These cells survived
desiccation on silica gel for 48 hrs or longer to a water content of less than 0.05 gH2O/gDW. In the present study, we isolated protoplasts
from these cultured cells and examined their desiccation tolerance. The isolated protoplasts were embedded in 3% agarose gel or
suspended in various desiccating media and desiccated on silica gel for different times at room temperature. The survival rate of protoplasts
after desiccation was determined from FDA staining and regrowth rate (cell-cluster formation). Under these desiccating conditions, the
water content of protoplasts was less than 0.1 gH2O/gDW after 24 hrs of desiccation. The survival rate after desiccation of the protoplasts
isolated from cells without being cultured in sucrose-enriched media was very low (<10%). However, the survival rate after desiccation of
the protoplasts isolated from cells cultured in sucrose-enriched media was very high (>80%) even in a desiccating medium with minimal
osmolarity for Marchantia protoplasts.
(a) Saitama University
P11007 Stomatal Responses to Humidity in Isolated Epidermes
Shope, Joseph C-presenter [email protected](a)
Mott, Keith A (a)
Peak, David (a)
We investigated the stomatal response to humidity in isolated epidermes of Tradescantia pallida and Vicia faba. Stomata responded to the
water vapor pressure on the outside and the inside of the epidermis, but the response was more sensitive to the inside vapor pressure. In
helium-oxygen air the kinetics of hydration and dehydration were 2.33 time faster than in normal air, which indicates that guard cells
hydrated and dehydrated entirely from water vapor, and there was no significant transfer of water from the epidermal tissue to the guard
cells. The stomatal aperture achieved at any given vapor pressure was consistent with water potential equilibrium between the guard cells
and the air near the bottom of the stomatal pore, and water vapor exchange through the external cuticle appeared to be unimportant for
the responses. Stomata responded to water vapor pressure on the outside of the epidermis in the presence or absence of living, turgid
epidermal cells. The possible role of water exchange between guard cells and the air in the stomatal pore in stomatal responses to humidity
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in intact leaves is discussed.
(a) Utah State University
P11008 Nitrate induction of root hydraulic conductivity in maize is not correlated with aquaporin expression
Gorska, Anna (a)
Zwieniecka, Anna-presenter [email protected](b)
Holbrook, N Michele (b)
Zwieniecki, Maciej (a)
Some plant species can increase the mass flow of water from the soil to the root surface in response to the appearance of nitrate in the
rhizosphere by increasing root hydraulic conductivity. Such behavior can be seen as a powerful strategy to facilitate the uptake of nitrate in
the patchy and dynamically changing soil environment. Despite the significance of such behavior, little is known about the dynamics and
mechanism of this phenomenon. Here we examine root hydraulic response of nitrate starved Zea mays (L.) plants after a sudden exposure
to 5 mM NO3- solution. In all cases the treatment resulted in a significant increase in pressure-induced (pressure gradient ~0.2 MPa) flow
across the root system by ~50% within 4 hours. Changes in osmotic gradient across the root were approximately ~0.016 MPa (or 8.5%)
and thus the results could only be explained by a true change in root hydraulic conductance. Anoxia treatment significantly reduced the
effect of nitrate on xylem root hydraulic conductivity indicating an important role for aquaporins in this process. Despite a 1 hour delay in
the hydraulic response to nitrate treatment, we did not detect any change in ZmPIP1 and ZmPIP2 gene families expression, strongly
suggesting that NO3- ions regulate root hydraulics at the protein level. Treatments with sodium tungstate (nitrate reductase inhibitor)
aimed at resolving the information pathway regulating root hydraulic properties resulted in unexpected findings. Although this treatment
blocked nitrate reductase activity and eliminated the nitrate-induced hydraulic response, it also produced changes in gene expression and
nitrate uptake levels, precluding us from suggesting that nitrate acts on root hydraulic properties via the products of NR.
(a) Arnold Arboretum, Harvard University (b) OEB, Harvard University
P11009 Xylem embolism refilling in poplar: the role of aquaporins and sugar transporters.
Secchi, Francesca-presenter [email protected](a)
Zwieniecka, Anna (b)
Holbrook, N Michele (b)
Zwieniecki, M (a)
The loss of transport function due to the embolism in xylem is a serious burden that can be reverted by refilling. Recent studies suggest
that refilling may happen despite presence of moderate tension in the xylem leaving an open question what mechanism is responsible for
this process. Here, we provide observations that embolism-refilling cycle are present in Populus trichocarpa even at low-level stress
diurnally. Further, we show that embolism formation is magnified by increasing degree of water stress and that refilling requires a reduction
of the stress by irrigation. Severe water stress imposed on plants requires a prolonged time for refilling (>24 hours) to occur despite that
leaf water potential recovery occur within few hours. For successful refilling water must be drawn to embolised vessels. This process
requires source of water and driving force. We hypothesize that living parenchyma cells provide water source and that driving force is
generated by sugars being uploaded to refilling xylem. To support this hypothesis we analysed changes in the starch/soluble sugars content
in the plant tissues (including wood, bark, and leaves) in control, stressed and irrigated plants during their diurnal cycles. This analysis is
overlaid on expression pattern of select gene encoding plasma membrane aquaporins and sugar transporters in the poplar stem. Results
suggest that there is a strong relation between refilling and expression pattern of sugar transporters and sugar content in the stem.
(a) Arnold Arboretum, Harvard University (b) OEB, Harvard University
Session P12 – Membrane Transport
P12001 Na+-induced K+ efflux from roots underlies salt sensitivity: transport mechanisms and ways of improvement
Pottosin, Igor I-presenter [email protected](a)
Chen, Zhonghua (b)
Zepeda-Jazo, Isaac (a)
Enriquez-Figueroa, Rene (a)
Cuin,
Tracey (b)
Palmgren, Michael (c)
Muniz, Jesus (a)
Shabala, Sergey (b)
So far, the main avenue in breeding crops for salt tolerance has been to reduce Na+ uptake and transport from roots to shoots. However, it
has been demonstrated recently on 70 barley varieties, contrasting in their salt sensitivity, that retention of cytosolic K+ is another key
factor in conferring salt tolerance. Combining non-invasive MIFE measurements of K+ fluxes with patch-clamp analysis of whole cell
currents we have shown that Na+-induced K+ efflux in barley root epidermis occurs primarily via outward rectifying K+ channels (KORC).
Surprisingly, expression of KORC was similar in salt- tolerant and sensitive genotypes. However, the former were able to better oppose
Na+-induced depolarization, thus minimizing K+ leak from the cytosol. The better control of membrane potential was at least in part due to
higher (up to 5-fold) activity of plasma membrane H+-ATPase in salt-tolerant varieties. In addition to highly K+-selective KORC channels,
activities of several types of non-selective cation channels were detected at depolarizing potentials. The expression of one of them, NORC,
capable of mediating K+ efflux coupled to Na+ influx, was significantly lower in salt-tolerant genotypes. Therefore, in salt stressed barley
roots the restricted activity of cation channels, due to their lower expression (NORC) and/or lesser depolarization (KORC), confers salttolerant genotype. Additionally, respective currents may be suppressed by endogenous inhibitors, polyamines. We have tested natural
polyamines on different ionic currents in barley epidermis and found out that some of them were potently inhibited. Our results further
emphasize that maintenance of cytosolic K+ -to- Na+ ratio is crucial for plant salinity tolerance. Supported by CONACyT grant 59007 to IIP.
(a) Centro Universitario de Investigaciones Biomedicas, Universidad de Colima, Mexico (b) School of Agricultural Science, University of
Tasmania, Australia (c) Department of Plant Biology, University of Copenhagen, Denmark
P12002 Functional analysis of the SUT sucrose transporter family in plants
Ward, John M.-presenter [email protected](a)
Sivitz, Alicia B (a)
Reinders, Anke (a)
Sucrose transporters (SUTs, also called SUCs) function in cellular uptake of sucrose and are required for long-distance transport of sucrose
in the phloem. Arabidopsis has nine homologous SUT genes and rice has five. SUTs are integral membrane proteins and are part of the GPH
cation symporter family within the MFS. By phylogenetic analysis, the SUT family is divided into three types (I, II and III). Our aim is to
analyze the transport activity of SUTs of each type to understand the range of SUT activity in plants and to start to relate amino acid
sequence differences with functional properties. All SUTs transport a range of glucosides including sucrose and we have found that type II
SUTs such as HvSUT1 from barley and ShSUT1 from sugarcane are much more selective for sucrose, and more selective for α-glucosides
over β-glucosides, than type I SUTs from Arabidopsis such as AtSUC2 and AtSUC9. We have now analyzed a type III SUT from Lotus
japonicus (LjSUT4) by expression in Xenopus oocytes and electrophysiology and show that it is a proton-coupled sucrose transporter with a
distinct substrate specificity compared to types I and II SUTs. LjSUT4 is localized to the vacuole membrane and we propose that LjSUT4
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functions in sucrose uptake from the vacuole. AtSUC1 (type I SUT) from Arabidopsis is highly expressed in pollen and localized to the
plasma membrane and we have found that atsuc1 mutant pollen is defective both in vivo and in vitro. AtSUC1 is also expressed in roots,
and its expression depends on intragenic sequence. atsuc1 mutant seedlings are defective in sucrose-induced signal transduction and have
fewer lateral roots than wild type indicating that AtSUC1 has important functions also in vegetative growth and development.
(a) University of Minnesota
P12003 Effect of serine palmitoyltransferase silencing on detergent-resistant membranes from arabidopsis
Carmona-Salazar, Laura-presenter [email protected](a)
Cahoon, Edgar B. (b)
Dietrich, C. (b)
Enriquez-Arredondo,
Consuelo (a)
Plasencia, Javier (a)
Gavilanes-Ruiz, Marina (a)
Extensive evidence in eukaryotic cells illustrates the existence of lipid rafts in vivo. In plants, the presence of these domains has been
related to the isolation of detergent-resistant membranes (DRM) from several species. Considering that sphingolipids are key components of
lipid rafts, disruption on their synthesis may impact rafts formation and consequently, their function. We used an Arabidopsis thaliana line
with diminished transcript levels of the two catalytic subunits from serine palmitoyltransferase (SPT, the first enzyme of sphingolipid
synthesis), due to mutation and silencing of both subunit genes. DRM from microsomal fractions of control and SPT deficient transcripts line
(40 % less mRNA from the control line) were isolated. DRM preparations from both lines showed similar yields and ultrastructure. However,
analysis of defense related proteins (plasma membrane H + -ATPase, 14-3-3 protein and NADPH oxidase) showed reduced levels in the SPT
silenced line as compared to the control. These results suggest that impairment on sphingolipid synthesis modifies the association of
proteins to microdomains, which may lead to modulate rafts function in interactions established between the plasma membrane and
pathogens in plant defense. Financed by UNAM (Fac. Quimica, PAIP 6290-02; DGAPA, PAPIIT IN207806). LCS is a fellowship recipient from
CONACYT (183583).
(a) Dept. Bioquimica, Fac. Quimica. University of Mexico (UNAM) (b) Donald Danforth Plant Science Center
P12004 Henry’s Electrophysiology Suite
Hills, Adrian-presenter [email protected](a)
Blatt, Michael R (a)
http://www.gla.ac.uk/departments/bmb/researchinterests/academicstaff/mikeblatt/softwareandhardwareforelectrophysiology
Although several commercial organizations produce electrophysiological software, they generally provide hardware-dependent packages,
designed for the patch clamp in the biomedical fields and large-scale pharmacological screening. Robust, hardware-independent software
suitable for impalement studies and the plant sciences has become hard to find. We have thus developed (and continue to extend) a
package, ―Henry‘s EP Suite,‖ which includes modules specific to whole-cell recording, and data analysis options tailored to the needs of the
plant scientist. The software runs under Microsoft Windows and is designed for ease and speed of use during experiments. The applications
make full use of ‗point, click & drag‘ facilities for designing voltage-clamp protocols, and for selecting data for analysis. Utilities include userdefined analysis envelopes that provide all-point or time-averaged IV plots during acquisition, and post-acquisition selection, analysis, curvefitting, digital filtering and export to a variety of 3rd party file formats. The control and acquisition modules work with a variety of interfaces,
clamp systems and amplifiers, and new modules are added regularly. As well as the control/acquisition and analysis application, ―Henry,‖
the package also includes ―N-Pro,‖ a program for improving signal-to-noise ratios in data-sets collected within the suite and with a variety of
3rd party software, and a virtual chart-recorder, ―Vicar.‖ An on-going, ‗developmental‘ application, ―Pandora,‖ contains state-of-the-art tools
for the analysis of single-channel (patch-clamp) data, and a variety of IV modeling tools. ―Henry― also allows acquisition of images and
spectra, synchronized with clamp-control and data collection.
(a) Plant Science Group, IBLS, University of Glasgow
P12005 Phloem-localized AAP2 transporter regulates distribution of amino acids from source to sink
Zhang, Lizhi-presenter [email protected](a)
Sanders, Ann (a)
Lee, Yong-Hwa (a)
Tegeder, Mechthild (a)
Amino acids are the predominant long-distance transport form of organic nitrogen in plants, and partitioning of amino acids from source to
sink organs, such as seeds, generally occurs via the phloem. To accommodate this process, the nitrogen compounds need to be loaded into
the sieve element-companion cell complex of the phloem in source leaves, or xylem-to-phloem transfer might occur along the translocation
path. While plasma membrane transporters have been suggested to be involved in phloem loading of amino acids, physiological evidence
was missing. We characterized the function of the Arabidopsis amino acid transporter AAP2 in phloem loading. Localization experiments of
AAP2-GFP proteins were performed in yeast and plant cells as well as throughout the plant. Further, AAP2 T-DNA insertion lines were
analyzed with respect to their phenotype and seed carbon, nitrogen and amino acid content. In addition, levels of seed storage compounds
were examined in mutant and wild-type plants. Our AAP2-GFP localization studies suggest that AAP2 is involved in loading of amino acids
into the companion cells of the phloem throughout the plant. Phenotypic analyses of aap2 plants revealed changes in seed yield and silique
number as well as in total biomass compared to wild-type. In addition, levels of total nitrogen and seed storage compounds were altered.
Overall, our results demonstrate that AAP2 is involved in phloem loading and amino acid distribution to sink organs, which affects sink
storage compound accumulation, sink number and overall plant biomass production.
(a) School of Biological Sciences, Center for Integrated Biotechnology, Center for Reproductive Biology, Washington State University
P12006 HMT-1 proteins are not involved in vacuolar sequestration of heavy metal-phytochelatin complexes. Evidences
from studies of HMT-1-like proteins from Schizosaccharomyces pombe, Caenorhabditis elegans and Drosophila.
Sooksa-nguan, Thanwalee-presenter [email protected](a)
Yakubov, Bakhtiyor (a)
Kozlovskyy, Volodya (a)
Howe, Kevin J.
(b)
Thannhauser, Theodor W (b)
Rutzke, Michael A (b)
Hart, Jonathan J. (b)
Kochian, Leon V. (b)
Vatamaniuk , Olena K.
(a)
Efficient heavy metal (e.g. Cd2+) detoxification relies on the activity of transport proteins that sequester heavy metal ions and/or their
complexes with specific cellular ligands into vacuoles. In plants and fungi, phytochelatins (PC), a family of small, cysteine-rich peptides that
are synthesized from glutathione (GSH) in the presence of heavy metals by PC synthases (PCS), have been proposed to facilitate vacuolar
Cd2+ sequestration. Based on studies in Schizosaccharomyces pombe, a half molecule ATP-binding cassette (ABC) transporter, SpHMT-1,
has been suggested to contribute to heavy metal tolerance by transporting Cd-PC complexes into vacuoles. Surprisingly, although Cd-PC
complexes localize preferentially to the vacuole of plant cells too, SpHMT-1 structural homolog(s) have been not yet detected in genomes of
plants. Since we showed previously that the PCS-dependent pathway operates and is essential for heavy metal detoxification in
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Caenorhabditis elegans, we sought to determine whether its genome possesses structural SpHMT-1 homolog(s). In so doing, we identified
CeHMT-1, and determined that it is acutely required for Cd2+ detoxification. However, our genetic studies in C. elegans suggested that
CeHMT-1 does not act in a linear PCS-dependent metal detoxification pathway. Furthermore, we discovered that DrHMT-1, an HMT-1-like
protein from Drosophila, is also involved in heavy metal detoxification. However, Drosophila genome does not possess PCS genes;
therefore, it is unlikely that DrHMT-1 acts in the PCS-dependent pathway too. We will present data demonstrating that HMT-1 proteins are
not involved in Cd-PC transport and will discuss possible mechanisms of the contribution of this subfamily of ABC transporters to heavy
metal detoxification.
(a) Department of Crop and Soil Sciences, Cornell University, Ithaca, NY (b) U. S. Plant, Soil, and Nutrition Lab, Cornell University, Ithaca,
NY
P12007 Pharmacologcal Evidence for a Sodium Channel Homolog in Plants that Acts as a Calcium Channel
Rivera, MIchael G.-presenter [email protected](a)
Moodie, Justina V. (a)
Chai, Christina (a)
Bronstein, Natalie B
(a)
Minorsky, Peter V (a)
The Na+ channels of animal cells are pharmacologically altered by agonistic drugs such as veratrine (V), and by antagonistic drugs such as
tetrodotoxin (TTX). These drugs show high specificity for Na+ channels in animal cells, although in the case of TTX, there is considerable
variation in sensitivity from cell type to cell type. TTX-sensitive Na+ channels are present in animals with organized nervous systems, down
to the platyhelminthes. Thus, the current paradigm is that V- and TTX-sensitivity arose during the early evolution of the Metazoa, and that
plants do not have V- or TTX-sensitive Na+ channels. Our preliminary studies, however, indicate that V, a Na+ channel agonist, and TTX, a
Na+ channel antagonist have opposite effects on the elongation of onion (Allium cepa) seedling radicles. V inhibits the elongation of onion
radicles, whereas TTX promotes elongation. The inhibitory effects of V were much more pronounced when CaCl2 was included in the
experimental medium than when NaCl was included. We have also found that V in the presence of Ca2+ causes a halving of the mitotic
index and induces many mitotic aberrations. We hypothesize that mitotic plant cells have a Na+ channel homolog that acts as a Ca2+
channel in planta.
(a) Mercy College
P12008 LjSUT4 - a vacuolar sucrose transporter from Lotus japonicus
Reinders, Anke-presenter [email protected](a)
Sivitz , Alicia B (a)
Ward, John M (a)
Plants contain small gene families of sucrose uptake transporters (SUTs or SUCs). Based on their amino acid sequence three distinct
subfamilies or types can be distinguished. Transport activities of type I and type II SUTs have been studied in some detail but much less is
known about type III SUTs. Here we have determined the transport kinetics and substrate specificity of LjSUT4, a type III SUT from Lotus
japonicus that is expressed in nodules. LjSUT4 has a low apparent affinity for sucrose. Like other SUTs LjSUT4 also transports a number of
different glucosides, however, the substrate specificity of LjSUT4 was found to be distinct from that previously determined for type I and
type II SUTs. As for most other SUTs, sucrose transport by LjSUT4 was coupled to protons. Generally SUTs have been described as
plasmamembrane-localized proteins. However, recently published data showed that type III SUTs closely related to LjSUT4, namely AtSUT4
from Arabidopsis and HvSUT2 from barley, localize to the tonoplast. Using heterologous expression of LjSUT4 fused to GFP we determined
that LjSUT4 is localized to the tonoplast as well. Based on transport activity and localization data we propose that LjSUT4 functions in
sucrose export from the vacuole. This is a novel function for a sucrose transporter.
(a) Dept. Plant Biology, University of Minnesota
P12009 Functional characterization of two high affinity purine transporters of Arabidopsis thaliana
Desimone, Marcelo-presenter [email protected](a)
Maurino, Veronica (b)
Grube, Esther (b)
Schumacher,
Benjamin (a)
Nestorova, Anna (a)
Winklbauer, Eva (a)
Flugge, Ulf-Ingo (b)
Nucleobases and derivatives play essential roles in all living organisms. Since the site of their synthesis frequently differs from the site of
use, transport is required in multicellular organisms. Several gene families encoding for putative nucleobase transporters have been
identified in plants. In this work, a functional characterization of two genes of Arabidopsis thaliana is presented. They belong to a novel
family of purine transporters recently identified in Aspergillus nidulans (azgA; aza-guanine resistant Aspergillus) and were designated as
AtAzg1 and AtAzg2 (A. thaliana aza-guanine resistant). Both genes were functionally expressed in a yeast mutant deficient in adenine
uptake (fcy2) to study transport features. They were able to transport purines including adenine, hypoxanthine, guanine with high affinity,
but not their nucleosides. Differences were found in the pH dependency of the transport: while AtAzg1 is fully active at acidic pH (max. at
pH 4.0), AtAzg2 can transport purines also at neutral or slightly basic pH, suggesting a difference in transport regulation. In planta studies
were conducted on T-DNA insertion mutants and overexpressor lines. Azg1 knock out mutants presented a conditional phenotype resistant
to aza-guanine and aza-adenine, whereas AtAzg1 overexpressor lines were hypersensitive to the purine analogs. This effect was not
observed in azg2 knock out mutants, suggesting that AtAzg2 transport these analogs very poorly. AtAzg1 and AtAzg2 overexpressor lines
showed higher adenine uptake rates compared with the controls indicating that both proteins transport purines in vivo. Subcellular
localization data by transient expression of GFP-fusion proteins, as well as expression results using GUS as a reporter for promoter activity
are presented.
(a) Center for plant molecular biology, University of Tubingen (b) Intitute for Botany, University of Cologne
P12010 Identification and characterization of potential Chloride transporters
Brumos, Javier-presenter [email protected](a)
Talon, Manuel (a)
Terol, Javier (a)
Colmenero-Flores, Jose M (a)
It is known that Chloride is essential for adequate plant development but often plants subjected to salt stress show injury symptoms in
shoots correlating with Cl- rather than with Na+ build-up. Chloride toxicity is very significant in Citrus plants, but also in other woody
species such as stone fruit trees and grapevines, cereals including wheat and barley and vegetables mostly bean, soybean and cotton
(White and Broadley, 2001). Therefore, chloride toxicity is a major constraint to horticultural production. The molecular characterization of
Cl- transport, scarcely characterized in plants, started with members of the Voltage-dependent Cl- channel (ClC) family (Barbier-Brygoo et
al, 2000). Recently a number of Cl- transporter genes have been characterized (Colmenero-Flores et al, 2007; Vahisalu et al, 2008, Negi et
al, 2008). We are currently using two approaches to identify genes and proteins involved in Cl- homeostasis: i) characterization of plant
ortholog genes of animal Cl- transporters; and ii) comparative genomics between Citrus genotypes with contrasting Cl--exclusion capacity.
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This approach allowed us to identify several potential Cl- transporters. We present here data concerning these genes, which expression is
modified in the root and leaves of citrus plants in response to either stress or nutritional Cl- treatments. -Barbier-Brygoo et al. (2000)
Biochim. Biophys. Acta 1465: 199-218 -Colmenero-Flores et al (2007). Plant J. 50: 278-292. -Negi et al. (2008). Nature 452 (7186): 483-6. Vahisalu et al. (2008). Nature 452 (7186):487-91. -Waterworth and Bray (2006). Ann Bot 98:1-8. -White and Broadley (2001). Ann. Bot. 88:
967-988.
(a) Genomics Department. IVIA
Session P13 – Mineral Nutrition
P13001 A unique mechanism for Fe3+ and Fe2+ acquisition in a halotolerant alga
Pick, Uri --presenter [email protected](a)
Paz, Yakov (a)
Weiss, Meira (a)
Katz, Adriana (a)
The halotolerant alga Dunaliella evolved a very efficient mechanism for Fe acquisition that involves binding of Fe3+ ions to the transferrin
TTf and internalization into acidic vacuoles. This mechanism enables rapid and massive binding of iron, effective discrimination of toxic
metals and a high capacity internal reservoir for iron. Under Fe deprivation, Dunaliella accumulates three additional proteins which associate
with TTf to create a high capacity Fe-binding complex. One of these proteins is a multi-copper ferroxidase,D-Fox, which functions in
oxidation and uptake of Fe2+ ions. We propose that Dunaliella acquired transferrins by gene transfer from primordial mammalian ancestors,
and adapted D-Fox from redox-driven to transferrin-mediated Fe uptake. This is an example of reshuffling of different proteins from diverse
organisms to create an efficient iron transport mechanism.
(a) The Weizmann Institute of Science, Deprtment of Biological Chemistry
P13002 Regulation of Iron-Sulfur Cluster Formation in Chloroplasts
Pilon, Marinus-presenter [email protected](a)
Abdel-Ghany, Salah E (a)
Murthy, Narayana NM (a)
Van Hoewyk, Douglas
(a)
Ye, Hong (a)
Pilon-Smits, Elizabeth AH (a)
The plastid iron-sulfur (Fe-S) assembly machinery is probably adapted to the special challenges presented by the need to assemble and
repair Fe-S clusters during oxygenic photosynthesis. Inducible RNAi studies and in vitro assays have indicated that the cysteine desulfurase
CpNifS is necessary for releasing elemental S from cysteine, a process which is required for Fe-S cluster formation in plastids [Van Hoewyk
et al., (2007) PNAS 104, 5686-5691; Ye, H. et al., (2006) J. Biol. Chem., 2006, 281, 8958-8969]. CpNifS functions in a complex, and CpNifS
activity is stimulated 50-80 fold by other stromal factors. Arabidopsis plastids contain three SufE-like proteins that stimulate CpNifS cysteine
desulfurase activity. SufE1 is the most abundant SufE-like protein and, like CpNifS, is expressed in all major tissues. SufE1 has an N-terminal
SufE-like domain and a C-terminal BolA-like domain unique to higher plants. We found that SufE1 - through its SufE-domain - binds to
CpNifS, accepts S and then dissociates to allow S delivery to downstream targets. Interestingly, the BolA-domain may have a regulatory role
and interacts with APS-reductase, a glutaredoxin-domain containing protein, which is involved in sulfur assimilation. This interaction
suggests a very interesting link between sulfur assimilation and Fe-S cluster assembly. SufE2 lacks a BolA domain and seems to have a
specialized role in pollen. The 3rd SufE, SufE3 contains both a SufE and a quinolinate synthase domain, which is required for the synthesis
of quinolinate, an intermediate in the formation of NAD. We found that the SufE-domain of SufE3 provides a direct link to CpNifS for the
assembly and repair of a oxygen-sensitive Fe-S cluster in the quinolinate synthase [Murthy et al., (2007) J. Biol Chem. 282:18254-18264].
(a) Colorado State University
P13003 NRM-1, a putative transcription factor involved in plant responses to nitrate availability
Stoerger, Vincent P.-presenter [email protected](a)
Liu, Xianan (a)
Bush, Daniel (a)
Nitrogen is a vital nutrient for plants that is most commonly acquired from the environment as an inorganic salt. Once assimilated, amino
acids are the principle form of nitrogen distributed to the heterotrophic tissues of the plant to support growth and development. Previous
work in our lab showed expression of the plant amino acid transporter gene AAP1 is regulated by nitrate availability. Therefore, one of the
goals of our lab is to understand the molecular mechanisms that regulate plant responses to this essential mineral nutrient. We used
microarray experiments to identified a previously uncharacterized Myb-type transcription factor, NRM-1 (Nitrate Responsive Myb), whose
transcript is rapidly up-regulated in roots by exogenous nitrate given to nitrogen starved plants. Further analysis showed nitrate is required
for NRM1 expression and GFP-tagged NRM1 protein localizes in the nucleus. NRM1 is part of a small gene family in Arabidopsis whose
members are part of the larger G2-type myb gene family. Knockouts of NRM1 exhibit wild type growth responses to nitrate availability
suggesting functional redundancy amongst members of the gene family. Double knock-outs of NRM1 and another prominent NRM-family
member expressed in the roots is under development. Changes in NRM1 gene expression and localization to the nucleus suggest NRM-1
plays a role in plant responses to nitrate availability.
(a) Colorado State University
P13004 Role of PHT1;8 and PHT1;9 Phosphate Transporters in pho2 and miR399-overexpressing Plants
Chen, June-Wei-presenter [email protected](a)
Wu, Pei-Chi (a)
Lai, Ya-Shiuan (a)
Chiou, Tzyy-Jen (a)
The miR399-overexpressing plants and pho2 mutant which is defective in UBC24, the target gene of miR399, accumulate up to 5 to 6 times
of normal phosphate (Pi) in the shoots because of increased Pi uptake from roots and Pi translocation from roots to shoots. The transcript
level of two Pi transporter genes, PHT1;8 and PHT1;9, was showed to be upregulated in the miR399-overexpressing plants and pho2
mutant. Thus, we hypothesized that enhanced Pi uptake in these plants may be caused by upregulation of PHT1;8 and PHT1;9 which
function downstream of UBC24. In this study, approaches via gain of function and loss of function of PHT1;8 and/or PHT1;9 were carried
out to examine such regulation. Transgenic plants overexpressing PHT1;8 and PHT1;9, respectively, accumulated slightly higher Pi in the
shoots. Overexpression of miR399 in the T-DNA knockout line of pht1;8 or pht1;9 still resulted in high level of shoot Pi. However, ~25%
reduction in shoot Pi was observed when miR399 was overexpressed in the pht1;8/pht1;9 double knockout mutant compared to the wildtype background. These observations indicate that upregulation of PHT1;8 and PHT1;9 is only part of reasons for the high level of Pi
accumulation in these plants and other Pi transporters or regulators are also involved in this process.
(a) Academia Sinica
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P13005 Systemic Regulation of Phosphate Homeostasis by MicroRNA399
Lin, Shu-I-presenter [email protected](a,b)
Chiang, Su-Fen (a)
Lin, Wei-Yi (a)
Tseng, Ching-Ying (a)
Wu, Pei-Chi
(a)
Chiou, Tzyy-Jen (a,b)
MicroRNA399s (miR399s) control inorganic phosphate (Pi) homeostasis by regulating the expression of PHO2 encoding an ubiquitinconjugating E2 enzyme (UBC24). Arabidopsis plants overexpressing miR399 or the pho2 mutant overaccumulate Pi in shoots. The
association of Pi translocation and co-expression of miR399s and PHO2 in vascular tissues suggests their involvement in long-distance
signaling. In this study, we used reciprocal grafting between wild-type and miR399-overexpressing transgenic Arabidopsis to dissect the
systemic roles of miR399 and PHO2. We analyzed quantitatively the level of miR399 precursors and mature miR399 and PHO2 mRNA, as
well as Pi accumulation, in scions and rootstocks. Arabidopsis rootstocks overexpressing miR399f showed high accumulation of Pi in the
wild-type scions because of reduced PHO2 expression in the rootstocks. Although miR399f precursors or expression was not detected, we
found a small but substantial amount of mature miR399f in the wild-type rootstocks grafted with transgenic scions, which indicates the
movement of miR399f from shoots to roots. The movement of miR399f was associated with the reduced PHO2 expression in the wild-type
rootstocks, resulting in high accumulation of Pi in the transgenic scions. Interestingly, the movement of miR399b/c was also observed, but
their targeting on the PHO2 transcript was less efficient than that of miR399f likely because of a mismatch at nucleotide 13. Furthermore,
we identified PHO2 siRNAs mediated by the cleavage of miR399s, which may function to refine the suppression of PHO2.
(a) Academic sinica (b) National Defense Medical Center
P13006 Long-distance Movement of miR399 from Shoots to Roots as an Early Response to Pi Deficiency
Chiang, Su-Fen-presenter [email protected](a)
Lin, Shu-I (a,b)
Chen, June-Wei (a)
Chiou, Tzyy-Jen (a,b)
We generated transgenic tobacco plants overexpressing Arabidopsis miR399b or miR399f. Similar to Arabidopsis, transgenic tobacco plants
over-accumulated Pi in shoots and displayed Pi toxicity as a consequence of suppression of tobacco PHO2. This suggests efficient targeting
of the tobacco PHO2 by Arabidopsis miR399. These transgenic tobacco plants were used for reciprocal grafting materials as performed in
Arabidopsis. As seen in Arabidopsis, the long-distance movement of miR399s from shoots to roots and the differential efficiency of miR399b
and miR399f in targeting the PHO2 transcript were also observed in grafted tobacco plants. The consistent results in both Arabidopsis and
tobacco plants suggest that the movement and regulatory network of miR399 could be common and conserved in plants. Time course
analysis of early Pi deficiency revealed that shoot-derived miR399s are responsible for early clean-up of PHO2 mRNA in roots, where
miR399s are not readily expressed. We propose that the long-distance movement of miR399s from shoots to roots is crucial to enhance Pi
uptake and translocation during the onset of Pi deficiency. Moreover, the analysis of the pho1 mutant provides additional support for
systemic suppression of PHO2 by the movement of miR399 from Pi-depleted shoots to Pi-sufficient roots. The regulation of miR399 and
PHO2 via long-distance communication in response to Pi deficiency is discussed.
(a) Academia Sinica (b) Graduate Institute of Life Sciences
Session P14 – Plant-Herbivore Interactions
P14001 Wound-induced sink strength (WISS) enhances carbon but not nitrogen import, favoring the production of carbonbased defenses in wounded poplar leaves
Arnold, Thomas M-presenter [email protected](a)
Appel, Heidi (b)
Schultz, Jack (b)
The induction of local sink strength in wounded plant tissues is a common first step in plant defense responses. In Populus, we have
demonstrated that wound-induced sink strength (WISS), which promotes carbohydrate (CHO) import, is a prerequisite for proanthocyanin
accumulation in grazed leaves. We hypothesized that: (1) WISS favors the production of c-based defense over n-based defenses and (2)
the presence of nearby sink tissues, which compete for CHO, reduce the ability of WISS to support strong responses at any one wound site.
To test this, we elicited the wound response in the LPI3 sink leaves of 600 hybrid poplar saplings, tracking the flow of 13C- and 15N-labeled
resources throughout the vascular system. Both insect grazing and 5mM JA pre-treatments boosted extracellular invertase activities, with
proportional increases in source-to-sink carbohydrate flow and accumulations of phenolic compounds in leaves. Rates of 15N import did not
increase. As a result, the C:N balance of imported resources increased. Factors such as branching, simultaneous woundings, leaf
development, and girdling complicated the WISS response, supporting proanthocyanin production where CHOs accumulated while
preventing them elsewhere. We conclude that WISS alters the resource balance at wound sites, favoring the accumulation of c-based
defenses in wounded leaves of Populus. In nature, when grazers trigger multiple WISS responses in interconnected source and sink tissues,
the resulting patterns of carbon-based defense are likely to be complex.
(a) Department of Biology, Dickinson College (b) Bond Life Sciences Center, University of Missouri
P14002 Molecular mechanisms underlying the growth-reducing effects of wounding
Farmer, Edward E.-presenter [email protected](a)
Transcriptional reprogramming within 3h of wounding affects the expression of an estimated 1.3% of protein coding genes in Arabidopsis.
The jasmonate signal pathway exerts control over the majority (67-84%) of these genes. Although wounding causes severe local tissue
disruption it also initiates a series of rapid events leading to the systemic activation of the jasmonate signaling pathway. Jasmonic acid (JA)
accumulates rapidly in response to a wound and is modified by conjugation to amino acids. These conjugates serve as ligands for
perception by an E3-type ubiquitin ligase that then targets repressor proteins for destruction. The recent identification of these ‗JAZ‘
repressor proteins has provided new opportunities for the study of the molecular controls over defense and growth control programs
initiated by wounding. One of the repressor proteins (JAS1/JAZ10) in Arabidopsis intervenes in growth control in damaged plants. Using this
protein in gain- and loss-of-function experiments revealed a conserved Jas motif that plays a critical role in jasmonate perception. By
studying the molecular mechanism of jasmonate signaling alongside experiments on post-wound development a more complete picture of
what plants do to promote their survival after attack is emerging.
(a) University of Lausanne
P14003 Systemic wound signaling in tomato leaves is cooperatively regulated by multiple plant peptides
Narvaez-Vasquez, Javier-presenter [email protected](a)
Orozco-Cardenas, Martha L (a)
Ryan, Clarence A (b,b)
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Hydroxyproline-rich glycopeptides containing 18-22 amino acids (HypSys peptides) were isolated recently from leaves of tobacco (Nicotiana
tabacum) and tomato (Solanum Lycopersicum) that are powerful inducers of protease inhibitor genes known to be induced by the defense
signaling peptide, systemin. The HypSys peptides are processed from polyprotein precursors, two from a tobacco precursor and three from
a tomato precursor. The tomato HypSys peptide precursor SlproHypSys, like the systemin precursor, prosystemin, is synthesized in phloem
parenchyma cells, and both precursor genes are expressed in tomato leaves in response to wounding and methyl jasmonate. Here we
demonstrate that the systemic wound expression of defense genes in tomato plants depends upon the cooperative synthesis of both
prosystemin and SlproHypSys to produce strong systemic wound response in tomato plants. The peptide signals derived from the
precursors amplify the synthesis of jasmonate, and in turn the peptides themselves. This provides a feed back loop to increase levels of
jasmonate in the vascular bundles as it moves through the plant as a long distance signal. This report provides the first demonstration of
the involvement of multiple plant peptides in regulating plant defense signaling.
(a) University of California Riverside-Botany and Plant Sciences Department (b) Washington State University-Institute of Biological Chemistry
P14004 Leucine aminopeptidase: A key regulator for insect defense
Walling, Linda L.-presenter [email protected](a)
Fowler, John (a)
Narvaez-Vasquez, Javier (a)
Aromdee, Dale (a)
The tomato leucine aminopeptidase A (LAP-A) accumulates after herbivory. LapA genes are JA-responsive and regulated by the late branch
of wound signaling. To investigate the role of LAP-A in defense, transgenic tomato plants that down-regulate or ectopically express LAP-A
have been identified and characterized. Analysis of LapA-silenced (LapA-SI), -antisense (LapA-AS) and -over-expressing (LapA-OX) lines
showed that LAP-A regulates the late branch, but not the early branch, of wound signaling. LapA-OX tomato lines showed that LAP-A was
necessary but not sufficient for wound signaling in tomato. After wounding, Pin1, Pin2 and polyphenol oxidase (PPO) RNAs accumulated to
higher levels and persisted for longer times in LapA-OX than in wild type plants. Reciprocally, LapA-SI and LapA-AS plants accumulated less
Pin1, Pin2 and PPO RNA and less Pin protein after wounding. Exogenous methyl jasmonate (MeJA) treatments of LapA-SI and LapA-AS lines
revealed that MeJA could not restore wound signaling. Furthermore, JA perception appears to be intact as determined by root elongation
phenotypes in the presence of MeJA. Collectively, these data indicate that LapA regulates an event downstream of JA biosynthesis and
perception. LapA-SI were hypersusceptible to caterpillar feeding and Manduca sexta performed better on LapA-SI than wild-type plants.
Reciprocally, LapA-OX plants were more resistant to M. sexta feeding incurring less tissue damage and inhibiting both caterpillar growth and
development. Current experiments focus on revealing the plastidial process regulated by LAP-A.
(a) University Of California
P14005 Enzymatic Properties of Mir1-CP, a Maize Defensive Protease with Remarkable Toxicity to Caterpillars
Luthe, Dawn S.-presenter [email protected](a)
Mohan, Srinidi (b)
Bassford, Erin R (b)
Shivaji, Renuka (b)
Ma, Peter W.K
(b)
Williams, W. Paul (c)
Maize Insect Resistance Cysteine Protease 1 (Mir1-CP) rapidly accumulates in the whorls of infested maize plants in response to caterpillar
feeding. The enzyme attacks and damages the insect peritrophic matrix (PM), an extracellular matrix that surrounds the food bolus and
protects the midgut from mechanical damage, toxins and microbes. Dose response analysis of purified recombinant Mir1-CP demonstrated
LC50 values of 1.8, 3.6, 0.6 and 8.0 ppm for corn earworm, tobacco budworm, fall armyworm and southwestern corn borer, respectively.
These values were the same order of magnitude as those determined for the Bacillus thuringiensis toxin Bt-CryIIA. In addition to being
directly toxic to the larvae, 60 ppb Mir1-CP synergized sublethal concentrations of Bt-CryIIA in all four species. The enzymatic properties of
recombinant wild-type Mir1-CP and two mutated forms were determined. These included KM, kcat, kcat/KM for several different substrates,
pH and temperature optima. In addition we determined that Mir1-CP was glycosylated and that it could bind chitin. The ability of the Mir1CP mutated forms to permeabilize the caterpillar PM in vitro was also examined.
(a) Pennsylvania State University (b) Mississippi State University (c) CHPRR USDA-ARS, Mississippi State
P14006 Plant Selenium Hyperaccumulation Functions as a Defense Against Herbivory
Pilon-Smits, Elizabeth A-presenter [email protected](a)
Freeman, John L (a)
Quinn, Colin F (a)
Galeas, Miriam L (a)
The element selenium (Se) is essential for many organisms but toxic at higher levels. Hyperaccumulator plants like Astragalus and Stanleya
can accumulate Se up to 1% of their dry weight. Our results from a range of lab and field experiments indicate that Se hyperaccumulation
can protect plants against herbivory, due to both deterrence and toxicity. Many invertebrate herbivores (aphids, spidermites, thrips,
grasshoppers, crickets, caterpillars) are deterred by Se-rich plants and suffer toxicity when they feed on them; Se also deters prairie dog
herbivory. Hyperaccumulators contain most Se in leaf hairs and epidermis of young leaves and reproductive tissues, typical for defense
compounds. Moreover, hyperaccumulators harbored fewer invertebrates than non-hyperaccumulators in the field, and fewer invertebrate
species. Some of the herbivores that were found feeding on hyperaccumulators in the field appear to be specialists. They are Se-tolerant
and accumulate levels of Se that likely affect higher trophic levels. Biochemical studies on Se-tolerant herbivores suggest their tolerance
mechanism is exclusion of Se from proteins, similar to their plant host. One Se-tolerant herbivore, a diamondback moth, was found to
harbor a Se-tolerant parasitic wasp, suggesting a higher trophic level adaptation. In conclusion, while Se accumulation protects plants from
generalist herbivores, some specialist herbivores have evolved resistance, as have some of their parasites, potentially forming a portal for
Se into the local ecosystem. These results give insight into the functional significance of Se hyperaccumulation and may have implications
for use of Se-accumulating plants for phytoremediation or as fortified food.
(a) Colorado State University
P14007 JAZ Repressor Proteins Control Jasmonate Signaling
Browse, John-presenter [email protected](a)
Thines, Bryan (a)
Niu, Yajie (a)
Figueroa, Pablo (a)
Jasmonates (JA) are required for plant defense against insects and other arthropods, and also against many pathogens. In Arabidopsis JA is
also required for fertility. Despite the importance of JA signaling, many details of the signaling mechanism remain unknown. JA-synthesis
mutants, such as fad3,7,8 and opr3, are sterile and made fertile by application of JA. Mutations in the F-box protein COI1 also abolish JA
responses, but the coi1 phenotypes are not rescued by JA. Transcriptional profiling of opr3 stamens treated with JA, allowed us to identify
genes encoding 12 JAsmonate Zim-domain (JAZ) proteins that are key regulators of JA signaling. JAZ proteins act to repress transcription of
JA-responsive genes. JA treatment causes JAZ degradation by the SCF(COI1)/26S proteasome pathway. Furthermore, the JA-isoleucine
conjugate, but not other JA derivatives (such as JA, OPDA, or ME-JA), promotes interaction between COI1 and JAZ proteins in the absence
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of other plant proteins. Our results suggest a model in which JA ligands promote the binding of the SCF(COI1) ubiquitin ligase to and
subsequent degradation of the JAZ repressor proteins, and implicate the SCF(COI1)-JAZ protein complex as a receptor for the plant
hormone JA-Ile. Many questions remain about the details of JAZ action and the roles played by conserved domains found in the family of
JAZ proteins. In particular two different models have been proposed to explain JAZ function (Nature 448:pp.661 & 666, 2007). We will
discuss these models in the context of new results obtained from protein-protein interaction studies and experiments with transgenic plants.
Our characterization of the JAZ family provides the basis for understanding the many different roles for JA in the development and
environmental responses of plants.
(a) Washington State University
P14008 Herbivore-Elicited Events in Legume Terpenoid Biosynthesis
Arimura, Gen-ichiro-presenter [email protected](a,b)
Kunert, Maritta (b)
Koepke, Sabrina (b)
Boland, Wilhelm (b)
Volatile terpenoids, the major products among the herbivore-induced plant volatiles in legumes, mediate interactions that attract natural
enemies of herbivores and serve as signals to neighboring plants. In this study, we demonstrated cross-talk among the signaling
components involving Ca2+, jasmonic acid, and ethylene; together these are responsible for the formation of volatile terpenoids in
Medicago truncatula and lima beans (Phaseolus lunatus). Like the crosstalk, herbivore-stimulated Ca2+ transients also influence the blend
of terpenoids, whose biosynthesis depends on the jasmonic acid (JA)/ethylene pathway in M. truncatula. Next, in order to investigate the
effect of diurnal versus nocturnal damage on the signaling pathway for volatile emissions from legumes, we used MecWorm, a robotic
device designed to reproduce tissue damage caused by herbivore attack. Lima bean leaves that were damaged by MecWorm during the
photophase emitted maximum levels of monoterpenes [β-ocimene] and C6 volatiles [(Z)-3-hexenyl acetate] in the late photophase. Leaves
damaged during the dark phase responded, distinctly. JA accumulated locally in direct response to the damage and led to the immediate
up-regulation of the β-ocimene synthase gene (PlOS) independent of the phase, that is, light or dark. In summary, damage-dependent JA
levels directly control the expression level of PlOS, irrespective of light conditions. In conclusion, we discuss a new perspective on possible
events (e.g., Ca2+ signaling) leading to terpenoid biosynthesis.
(a) Center for Ecological Research, Kyoto University (b) Max Planck Institute for Chemical Ecology
P14009 Modulation of jasmonic acid sensitivity by reflection signals. A phytochrome answer to the dilemma of plants
Ballare, Carlos L.-presenter [email protected](a)
Moreno, Javier E (a)
One of the most widespread responses of plants to the attack of herbivore insects is the activation of chemical defenses. Previous studies
have shown that plants down-regulate the expression of chemical defenses when they perceive an increased risk of competition with
neighboring plants. In the experiments reported here we provide evidence that this down-regulation of defense is mediated, at least in part,
by an effect of phytochrome on the sensitivity of the plant to jasmonic acid (JA). Plants exposed to supplementary far-red radiation (FR), a
competition signal perceived by phytochrome, had reduced levels of defenses compared to control plants grown without FR
supplementation. This was demonstrated by measurements of phenolic compounds and direct evaluations of plant tissue quality using
bioassays with Spodoptera frugiperdalarvae. Several JA-inducible genes were up-regulated in response to feeding by S. frugiperda
caterpillars in control plants, but this up-regulation was absent in plants exposed to FR radiation. Exogenous application of JA caused an
increase in the levels of phenolic compounds and up-regulated genes putatively involved in JA perception, signaling, and response. When
the plants were exposed to reflected FR, the phenolic response was abolished and the up-regulation of gene expression was cancelled or
greatly reduced in the case of ERF1, a regulator of JA- and ethylene-inducible genes, and PDF1.2 and HEL, two markers of JA response. The
JA-induced expression of MYC2 and VSP1, in contrast, was not affected by FR. We conclude that selective de-sensitization to JA is the
mechanism whereby the plant switches it resource allocation strategy, from defense to shade avoidance, in response to phytochromeperceived signals of intense future competition.
(a) IFEVA, Universidad de Buenos Aires
P14010 Indole-3-acetonitrile production from indole glucosinolates deters oviposition by Pieris rapae (white cabbage
butterfly)
De Vos, Martin-presenter [email protected](a)
Kriksunov, Ksenia L (a)
Jander, Georg (a)
http://www.bti.cornell.edu/GeorgJanderLab/DeVos.htm
Like many crucifer-specialist herbivores, Pieris rapae (white cabbage butterfly) uses the presence of glucosinolates as a signal for oviposition
and larval feeding. Arabidopsis thaliana glucosinolate-related mutants provide a unique resource for studying the in vivo role of these
compounds in affecting P. rapae oviposition. Low indole glucosinolate cyp79B2 cyp79B3 mutants received fewer eggs than wild-type,
confirming prior research showing that indole glucosinolates are an important oviposition cue. Transgenic plants overexpressing
epithiospecifier protein (ESP), which shifts glucosinolate breakdown towards nitrile formation, are less attractive to ovipositing P. rapae
females. Exogenous application of indol-3-ylmethylglucosinolate breakdown products to cyp79B2 cyp79B3 mutants showed that oviposition
was increased by indole-3-carbinol and decreased by indole-3-acetonitrile. P. rapae larvae tolerate a cruciferous diet by using a gut enzyme
to redirect glucosinolate breakdown toward less toxic nitriles, including indole-3-acetonitrile, rather than isothiocyanates. The presence of
indole-3-acetonitrile in larval regurgitant contributes to reduced oviposition by adult females on larvae-infested plants. Therefore, production
of nitriles via ESP in cruciferous plants, which makes the plants more sensitive to generalist herbivores, may be a counter-adaptive
mechanism for reducing oviposition by P. rapae and perhaps other crucifer-specialist insects.
(a) Boyce Thompson Institute for Plant Research
P14011 Arabidopsis defense against green peach aphid: role of plant lipids
Singh, Vijay-presenter [email protected](a)
Louis, Joe (a)
Morton, Jessica (b)
Reese, John C (c)
Shah, Jyoti (a)
Myzus persicae (Sulzer) Green peach aphid (GPA) is a generalist feeder and a well known pest of over a hundred economically important
plant species. We have established a GPA-Arabidopsis thaliana model system to identify and characterize genes involved in plant defense
against aphids. Using this system, we had previously demonstrated that the GPA inducible Arabidopsis PAD4 gene has an important function
in plant defense against aphid (Pegadaraju et al., 2005, 2007). PAD4 contributes to antibiosis and antixenosis (feeding deterrent).
Furthermore, we had shown that a recessive mutation in the Arabidopsis SSI2 gene results in heightened resistance to GPA that results
from increased antibiosis activity. Microarray analyses revealed that the MPL1 (MYZUS PERSICAE-INDUCED LIPASE 1) gene is expressed at
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elevated level in the ssi2 mutant and in GPA-infested wild type (WT) plants. The ssi2-conferred heightened resistance to GPA was
attenuated in the ssi2 mpl1 double mutant plant. No-choice tests revealed that in comparison to the wild type plant, GPA fecundity was
higher on two independent mpl1 mutant T-DNA insertion lines. In contrast, choice tests showed no significant difference in GPA number on
the mutant versus the WT, and electrical penetration graph monitoring of aphid feeding behavior indicated no differences in aphid feeding
on the WT versus the mpl1 mutant plants. We conclude that MPL1 is involved in antibiosis and unlike PAD4 does not contribute in any
measurable form to antixenosis. The GPA infestation-induced expression of PAD4 and MPL1 were found to be independent of each other.
MPL1 encodes a putative lipase and SSI2 is a stearoyl ACP-desaturase. Based on these results we propose that a lipid(s), or a product
thereof, is involved in plant defense against GPA
(a) University of North Texas, Department of Biology (b) Kansas State University, Division of Biology (c) Kansas State University, Division of
Entomology
P14012 Mechanism of jasmonate perception and its role in plant defense against insect herbivores
Howe, Gregg A. (a)
Katsir, Leron (a)
Chung, Hoo Sun-presenter [email protected](a)
Koo, Abraham J.K. (a)
Jasmonates (JAs) comprise a family of hormonally active oxylipins that have broad roles in regulating local and systemic defense responses
to herbivore attack. Bioactive JAs orchestrate defense responses by promoting the interaction of the F-box protein COI1 with, and the
subsequent degradation of, JAsmonate ZIM-domain (JAZ) proteins that repress the transcription of defense-related genes. We are using a
combination of biochemical and genetic approaches in both tomato and Arabidopsis to dissect the molecular mechanism of JA-mediated
anti-insect defense. Results of in vitro pull-down assays indicate that COI1-JAZ interactions are highly specific for jasmonoyl-isoleucine (JAIle) and closely related JA-amino acid conjugates. Ligand-binding studies, together with analysis of COI1-JAZ interactions in the yeast twohybrid system, further indicate that COI1 is an essential component of the jasmonate receptor. The highly conserved Jas motif located near
the C-terminus of JAZ proteins is necessary for JA-Ile-induced COI1-JAZ interaction. Ectopic expression of modified JAZ proteins lacking this
motif disrupts host resistance to some lepidopteran attackers, thus establishing a role for JAZ proteins in the regulation of plant defense
against herbivores. Our results are consistent with a model in which rapid accumulation of JA-Ile in wounded leaves is a signal for SCFCOI1dependent turnover of JAZ repressors, resulting in de-repression of early response genes that promote resistance to insect attack. This
research was supported by grants from the NIH and DOE.
(a) Michigan State University
P14013 Differential gene expression in whitefly (Bemisia tabaci)-infested tomato (Solanum lycopersicon) plants at four
developmental stages of the insect s life-cycle.
Estrada Hernandez, Maria G.-presenter [email protected](a)
Valenzuela Soto, Jose H. (a)
Delano Frier, John P. (a)
Plants differentially activate distinct defense pathways, depending on the inducing agent. Phloem-feeding insects (PF) obtain nourishment
directly from the host photo-assimilates and can act as viral vectors. The sweet potato (Bemisia tabaci, BT) and silver-leaf whiteflies (SLW)
(B. argentifolli ) are PF generalist insects, causing extensive agricultural damage world-wide. Previous studies in squash found that the
differential expression of the SLW1 and SLW3 genes, resembling those coding for M20B metallo-peptidases and cyanogenic β-glucosidases,
respectively, was induced by nymphs of SLW. In addition, the accumulation of PR proteins and the expression of genes coding for
homologues of NADPH oxidases, were detected in BT-infested tomato. Later, a transcriptome analysis of SLW-infested Arabidopsis mainly
involved the induction of SA-dependent defense pathways. In order to gain a further understanding of this plant-insect interaction, we
analyzed the differential expression of genes in virus-free BT-infested tomato plants at 4 different stages: egg (2 days post infestation, dpi),
crawler (7 dpi), 2nd and 3rd nymphal instar (12 dpi) and pupae (18 dpi) by subtractive suppression hybridization. The expression of genes
involved in the oxidative burst predominated, whereas defense genes included mostly those targeted against nematodes, fungi and viruses.
However, two chewing-insect-induced genes, coding for aspartic and thiol proteases, respectively, were detected. Also found were genes
involved in secondary metabolism, GABA and BABA biosynthesis, photosynthesis, C and N re-allocation, cytoskeleton, xylem and cell-wall
biogenesis, and signaling. Some of the above genes were induced in early stages and later repressed, as shown by macro-array assays.
(a) CINVESTAV Campus Guanajuato, Departamento de biotecnologia y bioquimica de plantas
P14014 Functional analysis of the tomato prosystemin promoter.
Aviles Arnaut, Hamlet-presenter [email protected](a)
Chattopadhyay , Debasis (b)
Delano Frier, John P. (a)
Systemin, an 18-amino acid polypeptide isolated from tomato leaves induces the systemic expression of defense genes in response to
mechanical wounding and herbivory. Systemin is derived from a 200-amino acid protein precursor called prosystemin. The systemic
signaling in tomato plants mediated by systemin has been widely studied; nevertheless, unknown processes remain, such as the signaling of
early events in damaged tissues that induce and restrict the expression of prosystemin gene in the vascular phloem parenchyma cells. We
report here the prosystemin promoter sequence isolated from a StuI DNA genomic library using a PCR-adaptor technique. The sequence,
probably representing the full-length promoter, has 2197pb and 74% AT. A bioinformatic search for putative cis-regulatory elements in the
promoter region was performed using PLACE, Reg Site Plant DB and AGRIS, finding motifs for response to sugars, abscisic acid, auxin,
gibberellin, methyl jasmonate, UV light as well as conserved boxes in genes that are expressed in pollen, endosperm and guard cells. In
order to study the function of the prosystemin promoter and characterize the regions with cis-regulatory elements that are critical to
wound-induced and vascular-specific expression of prosystemin gene, we made a series of 5‗ truncated promoter-GUS fusion constructs that
were introduced into Arabidopsis thaliana plants via Agrobacterium-mediated transformation.
(a) CINVESTAV Campus Guanajuato. Departamento de Biotecnologia y Bioquimica. Irapuato, Mexico. (b) National Centre for Plant Genome
Research. New Delhi, India.
P14015 Herbivore defense in forest trees: Multiplicity and functional complexity of induced defense in hybrid poplar
Constabel, Peter C.-presenter [email protected](a)
http://web.uvic.ca/%7Ecpc/
The diversity of plant-insect herbivore interactions predicts that different plant species have evolved distinct strategies of defense against
insects. Thus it is important to study defense mechanisms in a variety of plants, in particular in forest trees which must resist attacks from
many generations of pests. The genome of Populus trichocarpa contains a large number of genes related to pathogen defense, and should
also be a good source of pest defense genes. We have identified a suite of genes, encoding both known and novel poplar defense proteins,
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that are strongly upregulated following simulated herbivory, including phosphate and lipid-related enzymes as well as putative boiling stable
proteins. Kunitz trypsin inhibitors (KTIs) are highly represented among the induced genes, and found to belong to diverse gene family with
20-30 members. Functional analysis of recombinant KTIs in vitro determined that KTI sequence diversity is associated with functional
specialization, so that individual KTI proteins have a distinct profile of target proteases. Furthermore, the recombinant KTI proteins were
differentially effective against midgut proteases from two lepidopteran pests. Our results provide a rationale for the multiplicity of KTI genes
in the poplar genome, and are consistent with population studies suggesting rapid evolution of KTIs in poplar. To understand defense from
a whole-plant perspective, we also used differential 2-D gel electrophoresis to analyse changes in phloem proteins following leaf wounding.
Two consistently upregulated proteins were identified from phloem exudate and are being characterized further. We conclude that the
herbivore response of poplar has both unique and shared components compared with annuals such as Arabidopsis and tomato.
(a) Centre for Forest Biology and Department of Biology, University of Victoria
P14016 The tomato brassinosteroid receptor BRI1 increases binding of systemin to tobacco plasma membranes, but is not
involved in systemin signaling.
Malinowski, Robert (a,d)
Higgins, Rebecca (a)
Luo, Yuan (b,e)
Piper, Laverne (a,f)
Nazir, Azka (a)
Bajwa, Vikramjit S.
(c)
Clouse, Steven D. (c)
Thompson, Paul R. (b)
Stratmann, Johannes W.-presenter [email protected](a)
http://www.biol.sc.edu/faculty/stratmann.html
The tomato wound signal systemin is perceived by a specific high-affinity, saturable, and reversible cell surface receptor. The systemin
receptor was identified as the receptor-like kinase SR160, which turned out to be identical to the brassinosteroid receptor BRI1. Recently, it
has been shown that the tomato bri1 null mutant cu3 is as sensitive to systemin as wild type plants. We explored these contradictory
findings by studying the responses of tobacco plants to systemin. A fluorescently-labeled systemin analog bound specifically to plasma
membranes of tobacco suspension-cultured cells that expressed the tomato BRI1-FLAG transgene, but not to wild type tobacco cells. On the
other hand, signaling responses to systemin, such as activation of mitogen-activated protein kinases (MAPKs), were not changed in BRI1FLAG-overexpressing and in BRI1-silenced tobacco cells. Furthermore, in transgenic tobacco plants BRI1-FLAG became phosphorylated on
threonine residues in response to brassinolide application, but not in response to systemin. When BRI1 transcript levels were reduced by
virus-induced gene silencing in tomato plants, the silenced plants displayed a phenotype characteristic of bri1 mutants. However, their
response to overexpression of the Prosystemin transgene was the same as in control plants. Taken together, our data suggest that BRI1
can function as a systemin binding protein, but that binding of the ligand does not transduce the signal into the cell.
(a) University Of South Carolina, Department of Biological Sciences (b) University of South Carolina, Department of Chemistry and
Biochemistry (c) North Carolina State University, Department of Horticultural Science (d) University of Sheffield, Department of Animal and
Plant Sciences (e) University of Texas Southwestern Medical Center, Department of Internal Medicine (f) Dutch Fork High School, Irmo, SC
P14017 Specialist herbivore evasion of plant defense elicitation: Engineered cATPC as a strategy to recover cowpea (Vigna
unguiculata) recognition and defense against velvetbean caterpillars (Anticarsia gemmatalis).
Schmelz, Eric A-presenter [email protected](a)
Alborn, Hans T (a)
Teal, Peter E.A. (a)
http://www.ars.usda.gov/pandp/people/people.htm?personid=11781
Plants are attacked by an array of generalist and specialist herbivores with respectively broad and narrow host ranges. Moreover, plants can
produce quantitatively different defense responses to attack by even closely related insects. This raises the following question: Are adapted
specialists better at avoiding the induction of plant defense responses than generalists? In cowpea ( Vigna unguiculata), attack by generalist
armyworms (Spodoptera spp.) elicits rapid plant defense responses due to inceptin [Vu-In; +ICDINGVCVDA-], a peptide derived from
chloroplastic ATP synthase Υ-subunit (cATPC) proteins present in their oral secretions (OS). In contrast to armyworms, OS from the legume
specializing velvetbean caterpillar (VBC; Anticarsia gemmatalis) do not trigger rapid bursts ethylene, jasmonic acid and salicylic acid in
wounded cowpea leaves. We examined the fate of cATPC proteins in VBC OS and discovered the preferential accumulation of a C-terminal
Ala truncated peptide [Vu-In-A; +ICDINGVCVD-]. Not only is Vu-In-A inactive as an elicitor, but also a naturally occurring competitive
inhibitor of inceptin-induced responses. Libraries for amino acid substitutions at the inceptin C-terminus were screened for differences in
VBC gut proteolysis. Two modified inceptin amino acid sequences were discovered that retained elicitor activity and displayed preferential
accumulation in VBC OS. VBC that previously ingested these modified cATPC polypeptide sequences elicited stronger plant responses in
natural feeding assays compared to appropriate control insects. We propose transgenic expression of heterologous proteins containing
modified cATPC sequences in legumes as a strategy to recover plant recognition and rapidly induced-defenses against a specialist herbivore.
(a) USDA-ARS Center for Medical, Agricultural and Veterinary Entomology
P14018 The molecular basis of insect resistance in natural plant populations
Mitchell-Olds, Thomas-presenter [email protected](a)
Prasad, Kasavajhala (a)
Song, Bao-Hua (a)
Manzaneda, Antonio
(a)
Schranz, Eric (a)
Windsor, Aaron (a)
http://www.biology.duke.edu/mitchell-olds/
Although many plant species are genetically variable for resistance to herbivores, we have little understanding of the evolutionary
explanations for this ecologically important variation. Plausible explanations include local adaptation among different populations, or
frequency dependent selection between plants and insects, or tradeoffs between resistance and other components of fitness. Alternatively,
most of this genetic variation may be deleterious, due to a continual balance between purifying selection and new mutations. To answer
these questions requires analysis of cloned resistance genes in natural plant populations. Therefore, we are using positional cloning to
identify the genetic basis of variation in glucosinolate metabolism in Boechera stricta, a close relative of Arabidopsis. We have identified a
QTL that influences insect resistance as well as the spectrum of glucosinolates in leaves. By genetic fine mapping we identified ~800
recombinants in an 8 cM region containing this QTL. In addition, BAC sequence information from both parents reveals a known candidate
gene from the glucosinolate pathway. We also will discuss evolutionary and ecological analyses of this natural resistance polymorphism.
(a) Duke University
P14019 Insect herbivore-produced elicitors of plant volatiles: chemistry and biological activity
Tumlinson, James-presenter [email protected](a)
Three very different, non-enzymatic classes of compounds that induce plants to produce and/or release volatile organic compounds have
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been isolated and identified from the spit or regurgitant of insect herbivores. The first of these, the fatty acid-amino acid conjugates, was
first identified from the regurgitant of the beet armyworm larvae and subsequently found in other Lepidopteran larvae, as well as crickets
and Drosophila larvae. Subsequently, an 11 amino acid peptide, named inceptin, that induces cow peas to emit volatiles was identified in
the regurgitant of fall armyworm larvae. Most recently, we have identified a new class of elicitors, which we named caeliferins, from the
regurgitant of grasshoppers. These compounds are 16-carbon fatty acids with additional functional groups on carbons 2 and 16. They occur
in all grasshoppers examined thus far. We have only begun to explore the activity of each class of compounds across a rather limited range
of plant species. Evidence to date indicates that, while all these compounds induce at least some species of plants to produce volatiles, they
have different levels of activity on different species of plants.
(a) Penn State University
P14020 Homology of Hydroxyproline-rich Glycoprotein Systemins: Within and Beyond the Solanaceae Family
Pearce, Gregory-presenter [email protected](a)
Barona, Guido (a)
Chen, Yu-Chi (a)
Bhattacharya, Ramcharan (a)
Ryan, Clarence
A. (a)
Hydroxyproline-rich glycopeptide systemins (HypSys) are small peptide signals derived from larger precursor proteins (ProHypSys)
previously found exclusively in the Solanaceae family. They are involved in plant defense against insects and pathogens. Recently, this
family of defense genes was expanded to include a non-solanaceous member: sweet potato. All members of the proHypSys gene family
contain between 2-6 biologically active peptides of 16-20 amino acids that are processed for defense. The peptide signals are characterized
by a central motif consisting of 3-4 hydroxyprolines containing pentose attachments. Other defining features of ProHypSys are highly
conserved processing sites for the peptide signals, a ten amino acid conserved motif at the propeptidase processing site, and similar
carboxyl-termini. Sequences of the known proHypSys proteins have been analyzed for their differences and similarities in the hopes of
finding homologs throughout the plant kingdom. This study has led to the discovery of two new homologs from species outside the
Solanaceae family that are strong candidates for involvement as defense proteins.
(a) Washington State University
P14021 Plant defense responses to Aphis gossypii (cotton-melon aphid) feeding in resistant and susceptible melon
(Cucumis melo)
Anstead, James (a)
Samuel, Preethi (a)
Song, Ning (a)
Thompson, Gary A-presenter [email protected](a)
The genetic and physical characterization of the Vat aphid-resistance gene and its product supports a model of an R-gene mediated
resistance against A. gossypii. However, the recognition, signaling pathways, and proximate causes of resistance are unknown. Differences
in response to A. gossypii infestations between the nearly-isogenic melon lines, PMR 5 (Vat-) and AR 5 (Vat+), were investigated using
microarray analysis and quantitative real-time PCR. The results showed upregulation of a number of genes during aphid infestation,
including ethylene-related genes. Ethylene biosynthesis and signaling pathways are well characterized in melon from work on fruit ripening.
Ethaphon treatments resulted in significant upregulation of ethylene responsive genes in leaves of both PMR 5 and AR 5, including key
components of the ET signal transduction pathway CM-ETR1, CM-ETR2, CM-ERS1, CM-EIN2, CM-EIN3, CM-EIL1 and CM-ERF1 and the
downstream responsive genes CM-ssa-13, CM-Type 1-PI and CM-SAG-21. Analysis of the expression patterns by QRT-PCR after aphid
feeding showed the genes encoding positive regulators of the ethylene pathway were upregulated in resistant plants at early, but not late
periods of infestation. A transient 40-fold increase in the expression of the gene encoding the transcription factor CM-ERF1, a key integrator
between ethylene and JA pathways, was observed in the resistant AR 5 plants in response to early aphid infestation. Aphid feeding appears
to upregulate the octadecanoid biosynthesis genes LOX and OPR2 during late aphid infestation. These data are being related to studies
utilizing inhibitors of the ethylene and JA pathways to test if early ethylene signaling primes JA-mediated responses.
(a) Oklahoma State University
P14022 Salivary Enzymes: The First Line of Defense against Plant Defenses?
Felton, Gary W-presenter [email protected](a)
Eichenseer, Herb (b)
Ervin, Gary N (c)
We have characterized a salivary glucose oxidase in the polyphagous caterpillar Helicoverpa zea and found that it plays a role in suppression
of wound-induced defensive responses in some host plants. Additionally this multifunctional enzyme not only helps protect the caterpillar
from diseases, but it possesses enzymatic activity against a wide range of plant defensive metabolites possessing a glucosidic linkages.
Included in these substrates are known plant defenses including glucosinolates, cyanogenic glucosides, phenolic glucosides, and alkaloids
possessing glucose adducts. Further experiments indicate that glucose oxidase activity against glucosinolates suppresses isothiocyanate
production indicating its potential role in detoxification. We have screened nearly 100 caterpillar species across a multitude of lepidopteran
families for glucose oxidase and found a significant relationship between high enzyme activity and breadth of host range. Species with the
largest host range generally possessed higher levels of glucose oxidase. These new findings suggest that salivary secretions may be the first
line of defense against constitutive and inducible plant defenses.
(a) Penn State University (b) Pioneer, Johnston Iowa (c) Mississippi State University
P14023 Regulation of plant defense responses to cereal aphids through multiple signaling pathways
Huang, Yinghua-presenter [email protected](a)
Greenbug, a cereal aphid, establishes compatible interactions with a wide range of plant species; thus it has been one of the most
destructive pests of cereal crops, including wheat, barley and sorghum. The interactions between aphids and their hosts are complex and
dynamic, but the genetic mechanisms underlying both host-pest interactions and the host defense remain poorly understood. Our research
has been focused on examining the interactions of sorghum plant and greenbug at the molecular level to explore the genetic mechanisms
underlying host defense against attack by the aphid pest. In our lab, gene expression profiling has been employed to comprehensively
examine gene activities in host plants in comparison with non-host plants. Evidently a large number of defense genes and regulatory factors
were identified in response to greenbug feeding, which are involved in the salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signal
transduction pathways. A variety of functional analysis tools are also being used to associate these differentially expressed genes with key
signal or metabolic networks that regulate interactions between the host plants and the important pest aphids. The data obtained from the
aphid-induced gene expression profile and functional analyses are making important contribution to improve our understanding how
different pathways and biological processes interact or crosstalk during such interactions. Overall, these studies are providing new insights
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into the complex pathways governing host defense responses to phloem-feeding aphids.
(a) USDA-ARS and Oklahoma State University
P14024 Inducible Resistance in Populus: Critical Insights into Salicylate Phenolic Glycoside Biosynthesis
Babst, Benjamin A-presenter [email protected](a)
Harding, Scott A (a)
Tsai, Chung-Jui (a)
In a Populus nigra clone NC5271, known for its strong inducible resistance, concentrations of a common salicylate phenolic glycoside,
salicortin, more than doubled in plants exposed to limited herbivory for 3 weeks. Here we present a closer examination of the induced
increase in salicortin accumulation, as well as some insights into the biosynthetic pathway of the biologically active higher order salicylate
phenolic glycosides. Mechanical wounding of leaves with forceps resulted in a dramatic increase in salicortin within 3 days. Since turnover of
salicylate phenolic glycosides may be important, we fed ring-labelled [13C6]-cinnamic acid, a salicylate precursor, to leaf disks from
wounded and unwounded plants and measured unlabelled and labelled salicortin on LCMS to test for changes in biosynthesis. Incorporation
of the 13C from cinnamate into salicortin was increased, mirroring the increase in the total pool of salicortin. We also found evidence that
cinnamic acid is a precursor for the hydroxycyclohexen-on-oyl (HCH) moeity thought to confer the toxic and deterrent properties of many
higher order salicylate phenolic glycosides. Through competition feeding studies, and feeding of other labelled biosynthetic intermediates,
we found that various benzoates and salicylates may be incorporated into the salicylate ring of salicortin, but not all of these metabolites
were incorporated into the HCH ring. The insights gained from these studies are already aiding our ongoing functional genomic studies of
salicylate phenolic glycoside biosynthesis and regulation, and provide a basis for exploring the physiological underpinnings of costs
associated with the abundant salicylate phenolic glycosides found in most Populus and Salix species.
(a) Michigan Tech University
P14025 Defense related transcription factors in Solanum nigrum
Merker, Holger-presenter [email protected](a)
Schmidt, Dominik D (a)
Baldwin, Ian T (a)
http://www.ice.mpg.de/itb/home/home_en.htm
Emerging evidence suggests that different biotic and abiotic stresses elicit overlapping and non-overlapping transcriptional responses. While
some transcription factors (TFs) are commonly induced by multiple stress types other TFs with very specific modes of elicitation exist; these
ultimately allow a plant to fine-tune its responses in certain pest- and pathogen-rich environments. It is known that FACs (fatty acid-amino
acid conjugates) that occur in the oral secretions (OS) of certain lepidopteran larvae elicit specific plant defense responses; these differ
significantly from plant responses to pathogen attack or wounding alone. We were interested in TFs that are specifically regulated by leafchewing herbivores and that therefore are either elicited or amplified by OS or FACs. Profiling gene expression revealed that 21 putative TFs
were differentially regulated by FACs/OS. The bHLH TF, MYC2, is well known to mediate jasmonic acid (JA)-dependent transcriptional
responses, but the role of NAC-domain TFs in herbivore resistance is less clear. We have cloned several OS-responsive NAC genes of black
nightshade (Solanum nigrum), a wild relative of tomato and potato; these genes show different transcriptional profiles. Phylogenetic
analysis revealed that they belong to the ATAF subfamily of NAC-domain TFs. Plants transiently silenced in SnNAC1 using virus-induced
gene silencing (VIGS) show significant differences in their jasmonate profile and JA-dependent defense metabolites. Furthermore, larvae of
the solanaceous specialist Manduca sexta reared on leaves from silenced plants gained significantly more mass than did those reared on
control plants. Therefore, we conclude that SnNAC1 plays a crucial role in mediating plant responses to herbivorous insects.
(a) Max Planck Institute for Chemical Ecology
P14026 Dissecting the regulation of plant defense responses against a phloem-feeding insect
Goggin, Fiona L-presenter [email protected](a)
Wu, Chengjun (a)
Defibaugh-Chavez, Stephanie (a)
http://entomology.uark.edu/faculty/goggin.html
Aphids are herbivorous insects that are specialized to subsist on phloem sap, and many aphid species are major agricultural pests due to
their unparalleled reproductive capacity, their ability to manipulate host plant physiology, and their importance as virus vectors. We are
using tomato as a model system to investigate mechanisms of both basal resistance and R gene-mediated resistance against aphids. Using
the Affymetrix tomato microarray, we have identified over 200 genes in tomato that are responsive to aphid feeding, and we are utilizing
virus-induced gene silencing to assess the impact of a subset of these genes on plant-aphid interactions. Through this approach, we have
determined that the ethylene response factor Pti5 contributes to aphid resistance. This gene was previously shown to contribute to R genemediated bacterial resistance in tomato, and so our results highlight commonalities between aphid and pathogen resistance. We have also
used both mutant and pharmacological approaches to investigate the influence of key plant hormones on plant-aphid interactions. Whereas
jasmonic acid plays an important role in basal resistance to caterpillars, our results suggests that it is not an important component of
defenses against aphids in tomato. In contrast, aphids do appear to stimulate ethylene signaling, and our results suggest that the impact of
ethylene on aphid performance varies markedly depending upon the genetic background in which the interaction is tested.
(a) University of Arkansas
P14027 Functional stability of plant cystatins challenged with nontarget proteases-A co-evolutive counterpart to proteasemediated resistance in herbivorous insects?
Cantin, Line (a)
Cloutier, Conrad (a)
Michaud, Dominique-presenter [email protected](a)
Herbivorous insects developed several strategies to counteract the antidigestive effects of plant protease inhibitors, including notably the
ability to degrade these defensive proteins using nontarget digestive proteases. Here we measured the inhibitory potency of oryzacystatin I
(OCI), oryzacystatin II (OCII) and protease-generated truncated forms of these two inhibitors to assess their ability to remain active in the
presence of nontarget proteases challenging their structural integrity. Truncated forms of the cystatins were generated in vitro by tryptic or
chymotryptic treatment to identify potential sites for hydrolysis at basic or aromatic amino acid positions. As inferred from N-terminal
sequencing, both inhibitors showed susceptible cleavage points in the C-terminal region, in line with the occurrence of several basic and
aromatic residues downstream of the C-terminal, 2nd inhibitory loop. As shown by kinetic assays with recombinant versions of the truncated
cystatin variants expressed in E. coli, truncation in the C-terminal region had no measurable effect on papain inhibitory potency.
Interestingly, recombinant OCI expressed in transgenic potato leaves was stable in planta but truncated at the C terminus in the midgut of
Colorado potato beetle larvae fed the modified plant. This truncated version of the cystatin formed an SDS-stable complex with a major
OCI-sensitive protease in the insect midgut, suggesting a strong inhibitory effect in vivo despite partial hydrolysis. Overall, these
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observations illustrate the functional stability of OCI and OCII in the presence of nontarget proteases. They also point to the existence of a
reciprocal co-evolutive mechanism in plants counterbalancing the onset of protease-mediated resistance in their herbivorous enemies.
(a) Centre de recherche en horticulture, Universite Laval
P14028 Discovery and Applications of the Cyclotides: Circular Knotted Plant Proteins
Craik, David J-presenter [email protected](a)
The cyclotides [1] are a recently discovered family of plant-derived proteins that have applications in drug design [2] and agriculture [3].
They occur in plants from the Violaceae (violet), Rubiaceae (coffee) and Cucurbitaceae (cucurbit) families and have a diverse range of
biological activities, including uterotonic, anti-HIV, antimicrobial, and insecticidal activities, the latter suggesting that their natural function is
in plant defence. Individual plants express suites of 10-100 cyclotides at high levels (2g/kg plant weight). Cyclotides typically comprise 30
amino acids, contain a head-to-tail cyclised backbone and incorporate three disulfide bonds arranged in a cystine knot topology. In this
motif an embedded ring in the structure formed by two disulfide bonds and their connecting backbone segments is penetrated by a third
disulfide bond. The combination of this knotted and strongly braced structure with a circular backbone renders the cyclotides impervious to
enzymatic breakdown and makes them exceptionally stable. The cyclotides are the largest of several groups of naturally occurring circular
proteins that have been discovered over recent years [4]. This presentation will describe the discovery of the cyclotides in plants, their
structural characterization, evolutionary relationships and their applications in drug design. Their stability and compact structure makes
them an attractive protein framework onto which bioactive peptide epitopes can be grafted to stabilize them. [1]Craik D J, Cemazar M,
Wang C, Daly N L: Biopolymers: Peptide Science 2006, 84, 250 [2] Craik D J, Cemazar M, Daly N L: Curr. Opin. Drug Discovery and
Development 2006, 9, 251 [3] Jennings C, West J, Waine C, Craik D, Anderson M. PNAS 2001, 98, 579 [4] Craik D J: Science, 2006, 311,
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(a) University of Queensland
P14029 What makes Episyrphus balteatus (Diptera : Syrphidae) oviposit on aphid infested tomato plants ?
Verheggen, Francois J-presenter [email protected](a)
Wathelet, Jean-Paul (a)
Haubruge, Eric (a)
Under attack by insect pests, many plant species change their volatile chemical emissions to attract natural enemies. Most of the tomato
(Lycopersicon sp, Solanaceae) varieties are subjected to infestation by mollusks and insects, including the generalist aphid Myzus persicae
Sulzer (Homoptera, Aphididae). Episyrphus balteatus De Geer (Diptera: Syrphidae) is a generalist aphid predator that was here observed to
lay eggs on M. persicae infested tomato but not on non-infested plants. In order to identify the volatile chemicals that guide the foraging
and oviposition behavior of E. balteatus, we collected and identified volatiles released in the headspace of aphid infested tomato plants by
SPME-GC-MS. The identified chemicals were subsequently tested by electroantennography (EAG) on E. balteatus. Monoterpenes and
sesquiterpenes were identified, the main volatile chemicals being β-phellandrene, 2-carene, α-phellandrene, 3-carene and α-pinene.
Electrical depolarizations were observed for each tested monoterpene, with optimal responses ranging from -0.2 to -0.8 mV. Episyrphus
balteatus antennae showed dose-response relationships toward all the active chemicals. (E)-β-farnesene, the main component of the aphid
alarm pheromone, was the only active sesquiterpene, and is presumed to act as an ovipositing stimulus for E. balteatus.
(a) Gembloux Agricultural University
P14030 Wounding induced changes in the expression of stress related genes and phenolic compounds in VHb-hybrid aspen
line
Sutela, Suvi-presenter [email protected](a)
Jokipii, Soile (a)
Anttila, Anna-Kaisa (a)
Ylioja, Tiina (b)
Julkunen-Tiitto, Riitta
(c)
Haggman, Hely (a)
The hybrid aspen lines (Populus tremula L. x tremuloides Michx.) expressing haemoglobin gene (vhb) of Vitreoscilla-bacterium have
enhanced accumulation of starch in chloroplasts and higher relative volume of mitochondria compared to non-transgenic hybrid aspen lines.
Furthermore, VHb-lines have capacity to increase their secondary metabolite production under elevated UV-B illumination. We studied
wounding induced changes in the expression of stress related genes and phenolic compounds in VHb- and non-transgenic hybrid aspen
lines by feeding experiment with Chestnut moth larvae (Conistra vaccinii L.). Gene expression and the concentration of low weight phenolic
compounds were determined with cDNA microarray analysis combined with RT-PCR and HPLC-DAD, respectively, from samples collected
within a day of wounding. Besides the wounded leaves, analyzes were also conducted from the untreated leaves of the same tree. The
effect of herbivory to the gene expression levels of wounded leaves was similar in both lines, but in the non-transgenic line the reduction in
the gene expression associated with photosynthesis and induction of genes involved in the synthesis of secondary metabolites was more
severe. Moreover, the signal transduction of wounding induced more significant changes also in the mRNA levels of untreated leaves of
non-transgenic line. Altogether 30 phenolic compounds were identified and found present in all leaves of both lines. Even though the
wounding resulted in an induction of genes in-volved in the synthesis of phenolic compounds, the observed variation in the concentration of
phenolic compounds was more dependent on the hybrid aspen line or on the combined effect of line and treatment than on the wounding
treatment.
(a) Department of Biology, University of Oulu, Finland (b) Finnish Forest Research Institute, Suonenjoki Research Unit, Finland (c)
Department of Biology, University of Joensuu, Finland
P14031 Characterization of tomato trichome mutant hairless and its role in herbivore resistance
Kang, Jin-Ho-presenter [email protected](a)
Shi, Feng (b)
Jones, A. Daniel (b,c)
Howe, Gregg A (a,c)
Trichomes are specialized epidermal cells that often produce secretions that are thought to provide a first line of defense against insects
and pathogens. There are five types of trichomes on tomato (Solanum lycopersicum) called I, III, V, VI, and VII. Types III and V are non
glandular, while types I, VI, and VII are glandular trichomes. Here, we describe the morphological and chemical characterization of a
trichome mutant, hairless (hl). hl mutant has abnormal trichome cell expansion in all types of trichomes on leaves, stems, hypocotyls, and
flowers. To test the hypothesis that trichomes act as defense against insects, we measured the performance of specialist herbivore Manduca
sexta and generalist herbivore Trichoplusia ni on hl mutant. hl mutant was highly susceptible to both M. sexta and T. ni compared to WT
plants. hl mutant had reduced trichome numbers, reduced levels of sesquiterpenes, and reduced levels of phenolic compounds compared to
those of WT plants. These observations suggest that chemical compositions and/or structures of trichomes play an important role in plant
protection against herbivores
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(a) DOE Plant Research Laboratory, Michigan State University (b) Department of Chemistry, Michigan State University (c) Department of
Biochemistry and Molecular Biology, Michigan State University
P14032 The effects of anti-herbivory compounds within Ailanthus altissima leaf tissue on the feeding behavior of the
larvae of Hyphantria cunea
Ritz, Amanda M-presenter [email protected](a)
Wagner, Ryan L (a)
Secondary metabolic compounds play an integral role in plant defense mechanisms. One plant species that contains a number of interesting
secondary compounds is the invasive tree species Ailanthus altissima (Tree of Heaven). Prior research on Ailanthus altissima indicates that
secondary metabolic compounds in leaf tissue contribute to the anti-microbial, anti-fungal, and allelopathic (herbicidal) properties exhibited
by this species. This study investigated the role of secondary metabolites in the anti-herbivory properties of Ailanthus altissima leaf tissue
through larval feeding experiments conducted on Hyphantria cunea (fall webworm), a generalist herbivore that feeds on a variety of
deciduous trees including Juglans nigra (black walnut), Prunus serotina (black cherry), and Morus rubra (red mulberry). Choice larval
feeding studies using fresh Ailanthus altissima, Juglans nigra, Prunus serotina, and Morus rubra leaf tissue showed a clear avoidance of
Ailanthus altissima leaf tissue as demonstrated by a lack of consumption. Forced larval feeding studies conducted in the same manner
confirmed the anti-herbivory properties of Ailanthus altissima as indicated by 25% mean percent consumption of Ailanthus with a 18%
larval mortality rate, as opposed to 74% mean leaf consumption with a 0% mortality rate for the other tree species. Forced larval feeding
studies using fresh Juglans nigra leaves coated with Ailanthus leaf extract exhibited a 86% mean mortality rate as opposed to a 2% mean
mortality rate in untreated walnut leaves. Experiments regarding the anti-herbivory properties of Ailanthus on other Lepidoptera species are
in progress. Our current focus is on the biochemical characterization of the anti-herbivory components in Ailanthus leaf tissue.
(a) Millersville University
P14033 Analysis of carbohydrate and nitrogen reallocation as an herbivory tolerance mechanism in grain amaranth
(Amaranthus cruentus)
Vargas Ortiz, Erandi-presenter [email protected](a)
Martinez Gallardo, Norma A. (a)
Delano Frier, John P. (a)
Plants have developed a variety of strategies to cope with herbivory, including tolerance, which allows plants to sustain foliar tissue loss
with little or no fitness penalties. Tolerance involves several physiological changes including photo-assimilate (C) storage in less vulnerable
tissues, mostly roots. In order to evaluate tolerance to insect herbivory in amaranth, considered to be an (a) biotic-stress-tolerant species,
30-days-old A. cruentus plants were subjected to herbivory for three days by larvae of known lepidopteran pests, such as Spodoptera
exigua, S. littoralis, Estigmene acrea and Pholisora catullus. Subsequently, changes in C and nitrogen (N) partitioning and in sucrolytic
(invertases and sucrose synthase) activity were assessed throughout the development of plant in control and damaged A. cruentus plants.
Previously, the optimum pH for the above enzymes and their circadian activity pattern had been determined in leaves, stems and roots.
Circadian changes in the concentrations of sucrose, glucose, fructose, starch and total N were also measured in these tissues. Fitness traits
such plant height, root weight, and seed production at harvest time were assessed too. In this study, a circadian pattern in the enzymatic
activity and in N and C distribution was found. Herbivory also modified C and N partition and negatively affected the fitness of A. cruentus
plants, which had lower growth rates and productivity, thereby questioning its tolerance to insect infestation.
(a) CINVESTAV Campus Guanajuato
P14034 Proteomic analysis of amaranth leaves (Amaranthus sp.) subjected to insect herbivory or treated with methyl
jasmonate, an elicitor of insect resistance.
Navarro Melendez, Ariana L.-presenter [email protected](a)
Martinez Gallardo, Norma A. (a)
Valdes Rodriguez, Silvia E.
(a)
Delano Frier, John P. (a)
Herbivore attack and wounding cause diverse morphological and physiological responses in plants that are designed for defense, such as
distress signaling volatiles and toxic protein accumulation, that act as feeding deterrents. In many plant species, jasmonic acid is the signal
responsible for triggering the above events, both locally and systemically. The genus Amaranthus includes species used for grain and leaf
production and also some of the most aggressive weeds known. Grain and leaf amaranths are valued for their climatic adaptability,
tolerance to herbivore attack and high protein quality. The aim of this study is to identify amaranth proteins that could be involved in
defense against insect herbivores, using two-dimensional, (2D), electrophoresis. Thus, exogenous methyl jasmonate treatments or
herbivore assays with Spodoptera exigua larvae were performed using 5 weeks-old plants of two amaranth species: Amaranthus
hypochondriacus and A. hybridus. Leaf tissues were collected 24 h after treatment and were analyzed once the sample extraction and
preparation parameters were optimized to minimize the presence of plant-derived components that can seriously interfere with isoelectric
focusing and 2D. Three extraction methods were tested: TCA/acetone, phenol and Tris 40 mM; after qualitative 2D analysis, it was
concluded that the phenol method is the most suitable for amaranth leaf protein extraction, producing high protein yields, minimal streaking
and reducing the levels of abundant and interfering proteins, like Rubisco. Preliminary results showed the accumulation of differential
proteins of low molecular weight, in the acidic and basic range, in response to both treatments.
(a) CINVESTAV Campus Guanajuato
P14035 Molecular tagging of the BPH1 resistance locus to brown planthopper (Nilaparvata lugens Stal) through
representational difference analysis
Park, Dong-Soo-presenter [email protected](a)
Park, Soo-Kwon (a)
Lee, Jong-Hee (a)
Song, Song-Yi (a)
Yi, Gihwan (a)
Nam,
Min-Hee (a)
Oh, Byeong-Geun (a)
Jeon, Jong-Seong (b)
To identify BPH responsive genes, we employed a modified representational difference analysis (RDA) to detect less abundant transcripts
that were differentially expressed in SNBC61, a BPH resistant NIL carrying the Bph1 resistance gene, during insect feeding. Of three isolated
RDA genes, OsBphi252 was found to be closely located to Bph1 and OsBphi264 mapped near to the known quantitative trait locus (QTL).
DNA gel-blot analysis revealed that loci of the RDA genes in SNBC61 correspond to the alleles of the BPH resistant donor Samgangbyeo.
Expression analysis indicated that the RDA clones including OsBphi252 were found to be up-regulated in SNBC61 during BPH feeding.
Furthermore, genetic mapping analysis indicated that OsBphi252 is tightly linked to Bph1. These results suggest that OsBphi252 is a
candidate for Bph1 that functions an essential role during BPH resistance response. Thus, OsBphi252 can be useful in marker-assisted
selection (MAS) for resistance to BPH. [This work was supported, in part, by grants from the Crop Functional Genomic Center (CG1312,
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CG2111-2), the 21 Century Frontier Program, from the Biogreen 21 Program, Rural Development Administration]
(a) Yeongnam Agricultural Research Institute (b) Kyung Hee University
P14036 Comparative proteomic analysis of plants proteins that are stable in the lepidopteran gut
Herde, Marco-presenter [email protected](a)
Carr, Kevin M (b)
Wilkerson, Curtis G (c)
Howe, Gregg A (a)
http://www.prl.msu.edu
Plants produce an extraordinary range of compounds that exert toxic effects on arthropod herbivores. In addition to secondary metabolites,
proteins are also an important component of the plant‘s defensive arsenal against insect attack. Recent studies from our lab indicate that
many plant defense proteins are resistant to insect digestive proteases and, as a consequence, are highly enriched in the insect gut and
feces (frass). In this study, we employed a shotgun proteomic approach to identify leaf proteins that are stable during passage through the
digestive tract of the generalist herbivore Spodoptera frugiperda (Fall army worm), a serious pest of many crop plants. We analyzed the
protein content of frass collected from S. frugiperda reared on various host plants, including rice, maize, wheat, sorghum, barley, soybean,
cotton, and Medicago truncatula. In comparison to the total leaf proteome, we observed a substantial enrichment of plant proteins excreted
in the frass. Many of these proteins, including proteinase inhibitors, lectins, and vegetative storage proteins, are known to play a role in
plant defense against insects. We also identified proteins (e.g., JIP23 from barley) of unknown function that were previously shown to be
regulated by the jasmonate pathway for induced resistance to herbivory. Many other identified proteins are highly stable enzymes that have
not been previously linked to plant defense. These results will facilitate the identification of novel plant anti-insect proteins, and will also
contribute to our understanding of post-ingestive interactions between the plant proteome and components of the herbivore gut. This
research was supported by grants from the USDA NRI/CSREE and DOE.
(a) Department of Energy Plant Research Laboratory, Michigan State University (b) Research Technology Support Facility, Bioinformatic
Support Core, Michigan State University (c) Department of Energy Plant Research Laboratory and Michigan Proteome Consortium, Michigan
State University
P14037 Characterization of MAP kinase signaling in tomato wound response
Higgins, Rebecca C-presenter [email protected](a)
Yalamanchili, Roopa (a,b)
Ranf, Stefanie (a,c)
Stratmann, Johannes (a)
Plants must defend themselves from a wide array of biotic stresses, including herbivorous insects. In tomato leaves, the wound signaling
pathway is initiated by the peptide systemin upon insect attack or wounding. Systemin binds to the receptor kinase SR160, thus initiating an
intracellular signaling pathway involving a MAP kinase (MAPK) cascade. Systemin leads to activation of at least two tomato MAPKs, MPK1
and MPK2. MPK1 and 2 function upstream of JA biosynthesis and are required for the successful defense response against herbivory. We
have shown earlier (Higgins et al. 2007) that the wound signaling peptide systemin induces transient activation of MPK1/2 while the fungal
toxin FC induced prolonged activity of MPK1/2 and MPK3. This is associated with synthesis of jasmonic acid and expression of wound
response genes in response to systemin and synthesis of salicylic acid and pathogenesis-related (PR) genes in response to FC. We
hypothesize that MAPK activation kinetics contributes to signaling specificity. MAPKs are activated via phosphorylation by MAPK kinases
(MKKs). We cloned 4 MKKs from tomato and characterized the interaction of specific MPKs and MKKs using a yeast two-hybrid interaction
assay and transient co-expression in tomato protoplasts. We are now analyzing the activation kinetics of the MKKs in response to various
wound and pathogen signals and mechanisms that may lead to either prolonged or transient MAPK activity.
(a) University of South Carolina Dept. of Biological Sciences (b) Duke University Dept. of Biology (c) Leibniz Institute of Plant Biochemistry
Dept. of Stress and Developmental Biology D-06120 Halle (Saale) Germany
P14038 Analysis of feeding behaviour of Myzus persicae on Brassica nigra subjected to different watering regimes using
the electrical penetration graph (EPG) technique
Vickers, Laura H-presenter [email protected](a)
Bale, Jeff (a)
Pritchard, Jeremy (a)
Climatic change is arguably the greatest challenge facing agriculture over the next few decades. Many models predict that climate change
will alter the interaction between aphids and their host plants, but it is unclear if the response can be predicted for the whole feeding guild,
or whether aphid diversity only allows predictions to be made at the individual species level. Our studies are determining how a range of
aphid-host plant interactions are affected by drought to go some way towards establishing if the effect of climate change on the interaction
can be predicted. Brassica nigra is a naturally occurring plant in the UK, found along the south west coastline of Britain, an area anticipated
to experience dramatic changes in temperature and water availability. Using the electrical penetration graph technique, probing behaviour
of Myzus persicae on B. nigra individuals aged approximately 20 days was measured. This pattern was compared with probing behaviour of
M. persicae on drought stressed B. nigra. Feeding behaviour was scored as the time each aphid spent in pathway, apoplastic probing and
phloem feeding defined as either E1 (salivation) or E2 (ingestion). The number of cell penetrations and time spent in each penetration was
also scored. These observations, combined with experiments on aphid performance, will provide clues as to how the adaptability of the
insect-plant interaction is to climate change. Such knowledge is important in agriculture, but also as a tool for conservation strategies.
(a) The University of Birmingham
P14039 Regulation of terpene synthesis - the impact of environmental conditions and signal transduction cascades
Gaertner, Katrin-presenter [email protected](a)
Herde, Marco (a)
Gatz, Christiane (a)
http://www.ubpb.gwdg.de
Volatiles play an important role in plant-plant and plant-insect interactions and plants can emit different volatile bouquets to communicate
with their environment. Thus, it can be hypothesized that different volatile biosynthetic genes are regulated by different signaling cascades,
allowing their differential expression depending on the environmental conditions. Indeed, infection of Arabidopsis plants with Pseudomonas
syringae or Botrytis cinerea leads to expression of the geranyllinalool synthase (GES) and a myrcene/ocimene synthase (TPS4), whereas
feeding of the catarpillar Plutella xylostella only induces GES expression. Though expression of both genes requires jasmonic acid (JA) and
the F-box protein COI1, neither of them can be induced efficiently by JA or JA-Isoleucine. Treatment with JA and Ethylene (ET) leads to
TPS4 but not of GES expression, indicating that different signaling cascades are responsible for the differential expression pattern upon
biotic stress conditions. The regulation of TPS4 transcription differs from the regulation of the well-studied ET/JA inducible gene PDF1.2 in
two aspects: First, TPS4 but not PDF1.2 can be induced by the JA-mimic coronatine even in the absence of ET. Second, its expression is not
sensitive to the negative effect of SA. GES shows different modes of regulation depending on the stimulus: Induction by wounding requires
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the bHLH transcription factor MYC2, whereas induction upon infestation with P. xylostella functions independently of MYC2, indicating that
different JA-dependent signaling cascades merge on the promoter.
(a) General and Developmental Plant Physiology, Georg-August-University Goettingen, Germany
P14040 Investigating plant-aphid interactions in Arabidopsis; using functional genomics to investigate the role of the plant
amino acid transporter AAP1
Kemp, Harley-presenter [email protected](a)
Newbury, John (a)
Bale, Jeff (a)
Pritchard, Jeremy (a)
Extensive pesticide use has led to widespread development of resistance in aphids. The development of the understanding of interactions
between aphids and their host plants may help to inform new control strategies. Previous work suggests that an alteration in sieve element
(SE) nitrogen composition can affect an aphid‘s acceptance or rejection of the SE and so effect growth and reproductive performance. To
alter SE composition, several amino acid transporters were manipulated by creating insertional mutations in Arabidopsis thaliana. The effect
of an insertional mutation in the amino acid permease gene, AAP1, was determined by measuring whole plant phenotype, aphid feeding
behaviour and aphid performance comparing the effect on the generalist feeder Myzus persicae, and the specialist feeder Brevicoryne
brassicae. Several characteristics of plant phenotype were affected by the disruption to AAP1, with rosette leaf number and weight being
significantly reduced. Aphid feeding behaviour was significantly altered in aap1 plants. The mean time taken to reach sustained SE ingestion
(E2), and mean time spent in pathway was significantly greater for aphids feeding on aap1 plants. The increased time taken to reach E2
suggests that the disruption to AAP1 affected the aphids‘ ability to localize a suitable SE. This in turn suggests that the pathway composition
and therefore the cues used by the aphid may have been affected. This subtle but significant effect was observed independently in both
aphid species. Despite the delayed SE localisation, there was no significant effect on aphid performance. Aphid growth rate and
reproductive output data for both species suggested the gene‘s disruption had no effect on either aspect of aphid performance.
(a) The University of Birmingham, School of Biosciences
P14041 Characterization of the MAPKK-interacting protein CSN5, a subunit of the COP9 Signalosome, in tomato
Hind, Sarah R.-presenter [email protected](a)
Ranf, Stefanie (a,b)
Higgins, Rebecca C. (a)
Pancholi, Suchita (a,c)
Kandoth,
Pramod K. (a,d)
Stratmann, Johannes W. (a)
http://www.biol.sc.edu/faculty/stratmann.html
Our group studies how tomato plants are able to defend themselves against insect herbivory. An important part of this wound response
pathway is a mitogen-activated protein kinase (MAPK) cascade. Some wound-responsive MAPKs also function in defense pathways that
target microbial pathogens. While utilizing overlapping signaling components such as MAPKs, these wound- and pathogen-induced pathways
result in distinct cellular defense responses. We performed a yeast two-hybrid screen to identify proteins that interact with a MAPKK that
functions upstream of wound- and pathogen-responsive MAPKs. One protein identified in the screen is the tomato homolog of CSN5, a
subunit of the COP9 Signalosome Complex (CSN). The CSN partly controls the process of proteasome-mediated protein degradation by
regulating the activity of E3 ubiquitin-ligases, which function in targeting specific proteins for ubiquitination and subsequent degradation.
CNS5 has also been shown to have putative monomeric functions that may be independent of its function as the catalytic subunit of the
CSN complex; however, it is still unclear exactly what these functions are or how they are regulated. We hypothesize that MAPKKs are
targeted for degradation through interaction with CSN5. To test this hypothesis, we silenced CSN5 and found that CSN5-silenced plants
showed prolonged activation of the MAPKs while wild-type plants had only transient activation in response to wounding. Also, CSN5-silenced
plants showed reduced levels of wound-responsive genes and jasmonic acid as well as increased levels of pathogenesis-related genes and
salicylic acid. These results indicate that CSN5 regulates plant defense responses via the MAP kinase cascade and thus can act as a switch
between wound and pathogen response pathways.
(a) Department of Biological Sciences, University Of South Carolina (b) Department of Stress and Developmental Biology, Leibniz Institute of
Plant Biochemistry (c) University of South Carolina School of Medicine (d) Division of Plant Sciences, University of Missouri-Columbia
Session P15 – Plant-Pathogen Interactions
P15001 Rapid transformation and screening of soybean roots to identify gene constructs lethal to the soybean cyst
nematode (Heterodera glycines)
Matthews, Benjamin-presenter [email protected](a)
Kim, Kyung-Huan (b)
Baek, So-Hyeon (b)
Lee, Seong-Kon
(b)
Park, Soo-Chul (b)
Alkharouf, Nadim (c)
MacDonald, Margaret (a)
Klink, Vincent (a)
http://bldg6.arsusda.gov/benlab/
The soybean cyst nematode (SCN; Heterodera glycines) is the major pathogen of soybean (Glycine max) and causes an estimated $0.5$0.8 billion in losses per annum in the U.S. We identified genes expressed in soybean roots and in SCN before and during infection using
microarrays containing 37,500 soybean and 7,500 SCN gene probes. Also, we used laser capture microdissection (LCM) to isolate syncytia
from roots to study gene expression specifically at the feeding site. These analyses provided a group of soybean genes that may influence
soybean resistance to SCN. Then we identified cyst nematode genes that may be useful in developing soybean resistant to nematodes using
genetic engineering. The genes were selected by comparing the SCN EST database with genes from Caenorhabditis elegans. Genes were
identified that would cause C. elegans death if mutated or silenced. We developed a system to rapidly transform soybean roots and screen
DNA constructs to determine their effect on SCN survival. A series of transformation vectors, designated as pRAP, was constructed using
Gateway (Invitrogen) technology to rapidly clone DNA without restriction digestion. Gene over-expression, gene silencing (RNAi), and
promoter analysis can be studied using these vectors. The vectors contain the tetracycline resistance gene for easy selection of transformed
Agrobacterium rhizogenes K599 and the gene encoding enhanced green fluorescent protein for easy selection of transformed roots. We
transformed soybean roots with a series of vector constructs. The transformed soybean roots were challenged with soybean cyst nematodes
and analyzed to determine if there was a change in resistance compared to control roots. This system can be used for general studies in
functional genomics using plant roots.
(a) U.S. Department of Agriculture (b) Rural Development Administration (c) Towson University
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P15003 Regulation and functional insights into NIK-mediated antiviral signaling
Santos, Anesia A. (a)
Carvalho, Claudine M-presenter [email protected](a)
Mattos, Eliciane C (a)
Machado, Joao Paulo B
(a)
Fietto, Luciano G (a)
Fontes, Elizabeth P.B. (a)
The NSP-interacting kinase (NIK) receptor-mediated antiviral signaling has been identified recently as a virulence target of the geminivirus
nuclear shuttle protein (NSP). However, the NIK-NSP interaction does not fit into the elicitor-receptor model of resistance and hence the
molecular mechanism that links this antiviral response to receptor activation remains obscure. We found that NIK1 exhibits a stepwise
pattern of phosphorylation within the A-loop with distinct roles for different phosphorylation sites at Thr-474 and Thr-469. Mutations at Thr474 impaired autophosphorylation and kinase activation that are needed to transduce a defense response to geminiviruses. These results
establish that NIK1 functions as an authentic defense receptor as it requires activation to mediate an antiviral signaling. Furthermore, we
describe the identification of a ribosomal protein, rpL10, as a specific partner and substrate of NIK. Phosphorylation of cytosolic rpL10 by
NIK redirects the protein to the nucleus where it may act to modulate viral infection. While ectopic expression of normal NIK or a
hyperactive NIK mutant increases the accumulation of phosphorylated rpL10 within the nuclei, an inactive NIK mutant fails to redirect the
protein to the nuclei of co-transfected cells. Furthermore, loss of rpL10 function enhances susceptibility to geminivirus infection, resembling
the phenotype of nik null alleles. We also provide evidence that geminivirus infection directly interferes with NIK-mediated nuclear
relocalization of rpL10 as a counterdefensive measure. Our findings highlight the extraribosomal role of a plant rpL10/Jun interacting factor
homolog as the immediate downstream effector of NIK-mediated antiviral signaling.
(a) Universidade Federal de Vicosa
P15004 Pierces disease results from a systemic plant defense response.
Matthews, Mark A (a)
Gambetta, Gregory A-presenter [email protected](a)
Choat, Brendan (a)
Rost, Thomas L (a)
http://matthews.ucdavis.edu
Xylella fastidiosa (Xf ) is a xylem-limited bacterium that lives as a harmless endophyte in most plant species but is pathogenic in several
agriculturally important crops such as coffee, citrus, and grapevine (Vitis vinifera L.). In susceptible cultivars of grapevine, Xf infection
results in leaf scorch, premature leaf senescence, and eventually vine death; a suite of symptoms referred to as Pierces disease (PD).
Pathogenesis is thought to result from the accumulation of Xf bacteria and their associated gums leading to vascular occlusion and water
deficit. However, studies in our laboratory examining bacterial populations, plant water relations, and hormone responses during
pathogenesis challenge this hypothesis. The vascular occlusion hypothesis predicts a positive correlation between symptom severity and
pathogen concentrations, yet we found no clear relationship between bacterial populations and symptom development. Thus, high and
localized concentrations of Xf are not necessary for the formation of leaf-scorch symptoms. In most cases even when bacteria were present,
increasing Xf concentrations were not correlated with decreases in hydraulic conductance, and observed changes in water and solute
potentials were more akin to a program of natural senescence than simply to cellular level water deficits. Also, nitrogen concentration
decreased and ethylene production increased similarly as green leaf area decreased in symptomatic and naturally senescing leaves. Taken
together these results indicate that PD results from a systemic, ethylene-mediated defense response.
(a) University of California
P15005 Novel nucleocytoplasmic traffic GTPase identified as a functional target of the geminivirus nuclear shuttle protein
Carvalho, Claudine M-presenter [email protected](a)
Fontenelle, Mariana R (a)
Florentino, Lilian H (a)
Santos, Anesia A
(a)
Joao Paulo, Machado B (a)
Francisco, Zerbini M (b)
Elizabeth, Fontes P.B. (a)
In contrast to the accumulated data about the nuclear transport mechanisms of macromolecules, little is known concerning the regulated
release of nuclear exported complexes and their subsequent transcytoplasmic movement. The geminivirus nuclear shuttle protein (NSP)
facilitates the nuclear export of viral DNA and cooperates with the movement protein (MP) to transport viral DNA across the plant cell wall.
Here, we identified a cellular NSP-interacting GTPase (NIG) with biochemical properties consistent with a nucleocytoplasmic transport role.
We show that NIG is a cytosolic GTP-binding protein that accumulates around the nuclear envelope and possesses an intrinsic GTPase
activity. NIG interacts with NSP in vitro and in vivo and redirects the viral protein from the nucleus to the cytoplasm. We propose that NIG
acts as a positive contributor to geminivirus infection by modulating NSP nucleocytoplasmic shuttling and hence facilitating MP-NSP
interaction in the cortical cytoplasm. In support of this, overexpression of NIG in Arabidopsis enhances susceptibility to geminivirus
infection. In addition to highlighting the relevance of NIG as cellular co-factor for NSP function, our findings also have implications for
nucleocytoplasmic trafficking of cellular macromolecules in general.
(a) BIOAGRO, Dept. of Biochemistry & Molecular Biology, Federal University of Vicosa, Vicosa/MG, Brazil (b) BIOAGRO, Dept. of Plant
Pathology, Federal University of Vicosa, Vicosa/MG, Brazil
P15006 Dissecting Arabidopsis immune responses using molecular and chemical genomics
Knoth, Colleen-presenter [email protected](a)
Salus, Melinda (a)
Girke , Thomas (a)
Eulgem, Thomas (a)
The interactions of Arabidopsis and the pathogenic oomycete Hyaloperonospora parasitica (Hp) are used to study transcriptional
reprogramming during plant-pathogen interactions. Using microarrays, Arabidopsis genes were identified that exhibit a strong and
coordinated Late/sustained Up-regulation in Response to HP (LURPs). Individual LURP insertional mutants show defects in resistance to Hp.
AtWRKY70, a LURP gene encoding a WRKY transcription factor, is a key control point in this interaction. We have screened 42,000 diversity
oriented synthetic molecules to find compounds that perturb the expression of LURP-promoter::GUS fusions, transformed into Arabidopsis
plants, in the absence of Hp. We are currently characterizing Cmp67, a novel defense elicitor identified in this screen, using several
approaches. We are analyzing the responses of known defense mutants to Cmp67 to reveal its possible mode of action. Cmp67 appears to
specifically and transiently activate a distinct branch of the plant defense network and induces strong resistance to Hp and Pseudomonas
syringae, a plant-pathogenic bacterium. To further examine the effects of Cmp67 on the defense transcriptome, we will perform microarray
experiments. Also, we have initiated screens for mutants insensitive or hypersensitive to Cmp67 to be used for the identification of its
molecular target. Cmp67 and other synthetic elicitors identified from this screen may lead to development of novel pesticides. They will also
be invaluable tools for dissecting the plant defense network as they can be used to specifically activate defined nodes and branches of the
plant immune system and will facilitate its future examination at the systems level. (This work is supported by NSF-IOB grant No. 0449439
and NSF IGERT grant DGE 0504249).
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(a) NSF-ChemGen IGERT Program, Center for Plant Cell Biology (CEPCEB), Department of Botany and Plant Sciences, University of
California-Riversi
P15007 A chilling sensitive mutant of Arabidopsis affected in plant pathogen responses
Zbierzak, Anna Maria-presenter [email protected](a)
Doermann, Peter (a)
Low temperatures cause large economical losses in agriculture every year. Several mutants of the model plant Arabidopsis thaliana were
shown to be sensitive to growth at cold or freezing conditions. Here, we employ the chilling sensitive mutant chs1 of Arabidopsis (Hugly,
Somerville, 1992, Plant Physiol. 99, 197-202) to study factors involved in chilling stress and decipher the role of lipids in this process.
Exposure of chs1 to 13 degrees Celsius causes chlorosis and finally plant death. Map based cloning revealed that CHS1 belongs to the large
group of pathogen-related genes. In addition, expression of several pathogen-related genes is up-regulated in chs1 under cold conditions.
We expect that the characterization of the chs1 mutant of Arabidopsis on a biochemical and molecular level will expand our current
understanding of abiotic as well as biotic stress.
(a) Max-Planck-Institute for Molekular Plant Physiology
P15008 GRIK1 and GRIK2 are upstream activating protein kinases for SnRK1
Shen, Wei (a)
Ascencio-Ibanez, J. Trinidad (a)
Reyes, Maria (a)
Hanley-Bowdoin, Linda-presenter [email protected](a)
http://biochem.ncsu.edu/faculty/hanley-bowdoin/Pages/homepage.html
Plant responses to pathogens are complex and involve signaling networks that regulate diverse cellular processes. We showed previously
that two closely related Arabidopsis protein kinases, GRIK1 and GRIK2, interact with geminivirus Rep protein and their protein levels
increase substantially during viral infection. The GRIKs belong to a protein kinase family that includes yeast SAK1, TOS3 and ELM1 and
mammalian CaMKK and LKB1. These kinases activate their downstream kinases SNF1 and AMPK, respectively, by phosphorylating a
threonine residue in the activation loop. We used recombinant proteins to show that the GRIKs phosphorylate SnRK1.1 and SnRK1.2, the
Arabidopsis SNF1/AMPK homologs, at the equivalent threonine residues resulting in the activation of SnRK1 autophosphorylation activity.
We showed that the GRIK proteins and the activated form of SnRK1 accumulate specifically in young vegetative tissues, suggesting that
they constitute a protein kinase cascade that regulates and coordinates plant carbon and nitrogen metabolism during leaf development.
Unlike healthy plants, GRIK and SnRK1 can be detected in mature leaves of geminivirus-infected plants. This accumulation may reflect
recruitment of the GRIK/SnRK1 cascade that is normally restricted to young tissues to support the high metabolic requirements of infected
cells. This idea is supported by transcriptome analysis showing that SnRK1-regulated marker genes are differentially expressed during
geminivirus infection. Other studies have implicated SnRK1 in the host defense response in geminivirus-infected plants. Studies are in
progress to ask how these two potentially opposing roles of the GRIK/SnRK1 cascade are coordinated during geminivirus infection
(a) North Carolina State University
P15009 CRT1, an Arabidopsis ATPase that interacts with diverse resistance proteins and modulates disease resistance to
Turnip crinkle virus
Kang, Hong-Gu-presenter [email protected](a)
Kuhl, Joseph C (a,c)
Kachroo, Pradeep (b)
Klessig, Daniel F (a)
HRT is a CC-NBS-LRR-type resistance (R) protein that is required for resistance to turnip crinkle virus (TCV) in Arabidopsis. To gain insights
into HRT-mediated signaling, we used a genetic screen to identify mutants in which recognition of the TCV avirulence factor was
compromised. One mutant, crt1 (compromised recognition of TCV), carries a mutation that results in premature termination of a novel
ATPase protein that would otherwise contain a GHKL ATPase motif. Following TCV infection, crt1 developed a spreading hypersensitive
response and failed to prevent viral replication and spread, which were more pronounced when two closely related CRT1 homologs also
were partially silenced. crt1 also suppressed cell death induced by ssi4, a constitutively active TIR-NBS-LRR-type R protein, and by
Pseudomonas syringae carrying avrRpt2. CRT1 interacts with the NBS domain of HRT. In addition, CRT1 also interacts with SSI4, and two
other R proteins, RPS2 and Rx. Interestingly, ssi4-induced cell death was suppressed by some of the truncated CRT1 variants, perhaps by
disrupting interaction between the activated R protein and wild type CRT1. Taken together, the results argue that CRT1 is a novel and
important player in R gene-mediated signaling.
(a) Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA (b) Department of Plant Pathology, University of Kentucky,
Lexington, KY 40546, USA (c) U.S. Department of Agriculture, Agricultural Research Service, Palmer, AK 99645, USA
P15010 LeERF transcription factors regulate pathogenesis-related (PR) genes for enhanced tolerance to bacterial wilt in
AtCBF1 transgenic tomato
Li, Chia-Wen-presenter [email protected](a)
Sanjaya, (a)
You, Su-Juan (a)
Hsieh, Tsai-Hung (a)
Chan, Ming-Tsair
(a,b)
Pathogen attack adversely affects crop quality and productivity in most environments and has been the focus of the genetic improvement of
crops for many years. Using cDNA microarray technology, we demonstrated that constitutive expression of AtCBF1 in transgenic tomato
plants significantly activated the expression of several pathogenesis-related (PR) genes, which resulted in enhanced tolerance to Ralstonia
solanacearum (RS) infection, a causative agent of bacterial wilt (BW), without yield penalty. The disease tolerance in transgenic and H7996
plants (BW-resistant tomato line) was associated with systemic suppression of internal bacterial multiplication, a mechanism that does not
exist in wild-type plants. Electrophoretic mobility shift assay (EMSA) revealed that AtCBF1 specifically interacts with DRE/CRT but not GCCbox, an element present in the promoters of PR genes, which excludes the possibility of direct interaction. RT-PCR analysis revealed
constitutive expression of RAV and several ethylene-responsive-factor (ERF) family genes. Promoter transient assay revealed that LeERF5
and Pti6 binds to GCC-box and enhances promoter activity in Arabidopsis protoplasts. Promoters of LeERF5 and Pti6 revealed several RAV
binding sites; coexpression of LeERF5 promoter with LeRAV2 transactivates the reporter gene. Together, these results suggest that LeERFs
act as intermediate transcription factors between CBF1 and PR via LeRAV in tomato, which results in enhanced tolerance to RS. They also
shed light on the mechanism of host regulatory proteins in response to RS infection.
(a) Agricultural Biotechnology Research Center, Academia Sinica (b) Academia Sinica Biotechnological Experiment Center in South Taiwan
Tainan
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P15011 Cyclic nucleotides act as an early signal upstream from Ca2+ in plant innate immunity
Ma, Wei-presenter [email protected](a)
Ali, Rashid (a)
Smigel, Andries (a)
Lemtiri-Chlieh, Fouad (a)
Verma, Rajeev
(a)
Gehring, Chris A (b)
Berkowitz, Gerald A (a)
Ca influx into plant cells is a critical early signal in plant innate immune responses leading to nitric oxide (NO) generation and hypersensitive
response (HR) to avirulent pathogens. However, not much has been clarified about two grand challenges in plant biology; what are the
proteins that facilitate cytosolic Ca elevations during the signal cascade, and how is recognition of a ‗nonself‘ invader transduced to altered
regulation of Ca transport. In the case of pathogen perception signaling events, recent work has identified leucine-rich-repeat receptor like
kinases (LRR-RLKs) as initial sentry receptors allowing for perception of pathogens through physical interaction with Pathogen-Associated
Molecular Pattern (PAMP) molecules which, upon recognition, initiate the signaling cascade. We have recently demonstrated involvement of
cyclic nucleotide (cNMP) gated (i.e. activated) cation channels (CNGCs) as contributing to the Ca flux upstream from the HR cascade. Here,
we used biochemical approaches to identify cNMPs as involved in translating pathogen recognition and PAMP perception into a cytosolic
signal leading to Ca influx (through CNGCs) and downstream innate immunity and HR signaling. Results of patch clamp experiments,
monitoring cytosolic Ca levels in aequorin-expressing plants, HR in plants, and NO generation in response to PAMPs and pathogens all link
cNMPs with this signal cascade. Bioinformatic approaches intriguingly identify a nucleotide cyclase functional domain in some LRR-RLKs
involved in pathogen signaling. Thus, we can present a new model linking several molecular events as involved in plant innate immunity
signal perception and transduction. Supported by NSF award 0721679.
(a) Department of Plant Science, University of Connecticut, Storrs, CT 06269-4163, USA (b) Department of Biotechnology, University of the
Western Cape, Bellville, South Africa
P15012 Differences in G-protein and Ca-channel involvement in ABA and pathogen signaling to nitric oxide and hydrogen
peroxide in the guard cell.
Walker, Robin K-presenter [email protected](a)
Berkowitz, Gerald A (a)
ABA plays a vital role in various plant physiological processes; orchestrating effects on seed germination and development, and Cadependent guard cell effects on stomatal aperture. Guard cells respond to the presence of pathogen associated molecular pattern (PAMP)
molecules (such as lipopolysaccharide (LPS)) through a signaling cascade involving Ca as well; including a rise in Ca/calmodulin (CaM), and
Ca/CaM-activated nitric oxide (NO) generation as well as H2O2 generation as steps in a plant innate immunity signaling cascade. This
signaling pathway leads to the hypersensitive response (HR) to avirulent pathogens in planta. Here, we identify differences in ABA and
pathogen/PAMP signaling in the guard cell. Previous work has shown, using G-protein loss-of-function mutants such as gpa1 agb1 that Gproteins are involved in ABA signaling in seed development. We find that ABA induces NO and H2O2 generation in wild type guard cells and
this ABA signaling is inhibited from wild type in guard cells of the gpa1 agb1 G-protein mutant, while LPS dependent H2O2 generation was
not affected. H2O2 generation and HR in response to avirulent pathogen infection were also not affected in G-protein mutant plants. Prior
work has found that LPS and pathogen signaling is impaired in a Ca-conducting channel loss-of-function mutant (dnd1). In contrast, ABA
dependent NO and H2O2 generation in dnd1 guard cells is similar to wild type. These results suggest that Ca channels required for
pathogen signaling may be different than those involved with ABA signaling in the guard cell. G-proteins may be involved in ABA signaling
(perhaps mediating Ca channel activation) while Ca channel activation during pathogen perception signaling may not involve G-proteins.
Supported by NSF award 0721679.
(a) Department of Plant Science, University Of Connecticut, Storrs, CT 06269
P15013 Innate immunity signaling: cytosolic Ca2+ elevation as an early signal is linked to downstream nitric oxide
generation through the action of calmodulin or a calmodulin-like protein
Ma, Wei-presenter [email protected](a)
Smigel, Andries (a)
Tsai, Yu-Chang (b)
Braam, Janet (b)
Berkowitz, Gerald A (a)
Ca rise and nitric oxide (NO) generation are essential early steps of plant innate immunity, and lead to hypersensitive response (HR) to
avirulent pathogens. The mechanism linking Ca rise to NO generation is unknown. Arabidopsis dnd1 mutants have a disrupted Caconducting channel CNGC2 and do not undergo HR. We restore HR (to avirulent Pseudomonas syringae pv. tomato (Pst)) in dnd1 plants
with the NO donor SNP. In wild type (WT) plants, the Ca-channel blocker Gd and the calmodulin (CaM) antagonist W7 prevent NO
generation and HR to Pst. W7 does not prevent Pst-induced cytosolic Ca rise in plants, thus CaM acts downstream from Ca. Using the guard
cell of leaf epidermal peels as a model system, we find that W7 and the Ca chelator EGTA both impair NO generation induced by the
bacterial pathogen Pattern Associated Molecular Pattern (PAMP) elicitor lipopolysaccharide (LPS). Animal NO synthase (NOS) activation is
Ca/CaM dependent. Here, we present biochemical and genetic evidence consistent with a similar regulatory mechanism in plants; a
pathogen-induced Ca signal leads to CaM and/or a CaM-like protein (CML) activation of NOS. CAM antagonists and EGTA block NO
generation in WT Arabidopsis leaf protein extracts. CML24 is one of many Arabidopsis CMLs. Innate immune response phenotypes (HR to
Pst, LPS dependent NO generation in guard cells, and Pst induced NO burst) are impaired in loss-of-function cml24 mutant plants. NO
generation in cml24 leaf extracts is reduced from WT. In summary, this work supports the following model. Ca influx into the cytosol
through CNGC2 activates CaM and/or a CML which acts as a signal to induce downstream NO synthesis as intermediary steps in pathogen
perception signaling leading to HR. Supported by NSF awards 0721679 (GAB) and 0321532 (JB).
(a) Department of Plant Science, University of Connecticut, Storrs, CT 06269-4163, USA (b) Department of Biochemistry and Cell Biology,
Rice University, Houston, TX 77251, USA
P15014 Functional characterization of CLE peptides from a plant-parasitic nematode, Globodera rostochiensis
Lu, Shun-Wen (a)
Wang, Jianying (b)
Chen, Shiyan (a)
Yu, Hang (a)
Mitchum, Melissa G (b)
Wang, Xiaohong-presenter
[email protected](a,c)
Recent evidence suggests that plant-parasitic cyst nematodes secrete ligand mimics of plant CLAVATA3/ESR (CLE) peptides to modify
selected host root cells into multinucleate feeding sites. Parasitism genes encoding for CLE-like peptides were cloned from the potato cyst
nematode, Globodera rostochiensis, and found to be expressed in the dorsal esophageal gland cell of the nematode during feeding site
initiation and maintenance. Gene structure analysis grouped Gr-CLE genes into two major classes, Gr-CLE-1 and Gr-CLE-4, in which Gr-CLE4 was confirmed to have multiple copies in the genome. Interestingly, unlike most plant CLEs and the nematode CLEs of the genus
Heterodera, members of the G. rostochiensis CLE peptide family were found to contain multiple CLE domains. Overexpression of either GrCLE-1 or Gr-CLE-4 in Arabidopsis under the control of the CaMV35S promoter produced phenotypes resembling those produced by plant
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CLEs including wuschel-like seedlings, generation of wuschel flowers, short roots, anthocyanin accumulation, delayed development, and
seedling death. In vitro application of synthetic 12-amino acid peptides, corresponding to the CLE motifs of Gr-CLE-1 and Gr-CLE-4, to the
roots of Arabidopsis, tomato, and potato caused a short root phenotype. Transient expression of the full-length Gr-CLE-1 gene as a Cterminal tagged protein in Nicotiana benthamiana leaves revealed that Gr-CLE-1 was processed into different forms of potentially
membrane-bound proteins, suggesting a possible proteolytic processing of the Gr-CLE-1 CLE domains in vivo. Our studies suggest that this
novel class of nematode CLEs has functional similarity to plant CLE signaling peptides and highlight an important role for ligand mimicry in
plant parasitism by G. rostochiensis.
(a) Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY (b) Division of Plant Sciences and Bond Life
Sciences Center, University of Missouri, Columbia, MO (c) Biological Integrated Pest Management Research Unit, USDA-ARS, Ithaca, NY,
USA
P15015 A suite of novel synthetic elicitors as tools for systems-level analyses of the plant defense network
Salus, Melinda S.-presenter [email protected](a)
Schroeder, Mercedes M. (a)
Knoth, Colleen M. (a)
Eulgem, Thomas A.
(a)
Plants have an intricate immune system that responds to pathogen infection via a complex regulatory network. This network consists of at
least 3 interconnected branches dependent on the hormones, Jasmonic Acid (JA), Salicylic Acid, and Ethylene (ET). Chemical genomics
utilizes small molecules to perturb regulatory mechanisms in vivo allowing for high levels of target specificity and real time control of
biological processes often across species barriers. We use this approach to discover novel synthetic elicitors (SEs) that target specific
domains of the defense web. This will allow us to study the behavior and architecture of this network and discover novel defense
components. We are performing high-throughput screens of chemical libraries for SEs that activate pathogen-responsive reporter genes in
Arabidopsis. Using promoters of LURP (late up-regulated in response to Peronospora) and JEDI (JA/ET Dependent Induced) genes, we
designed reporter lines responsive to different defense-stimuli enabling us to identify compounds targeting distinct domains of the defense
web. Furthermore, we identified multiple pathogen-responsive Arabidopsis enhancer-trap lines that will be used to screen for additional SEs.
These lines are also being analyzed to identify new defense promoter elements as well as the genes they influence. SEs discovered by our
study may allow for the design of new pesticides providing protection to plants by stimulating their inherent defense mechanisms. In
addition, multiple SEs may be simultaneously applied to trigger complex responses mimicking defined pathogen induced states of the plant
immune system for detailed network analyses. This work is supported by NSF-IOB grant No. 0449439 and NSF IGERT grant (DGE 0504249).
(a) University of California Riverside, Department of Botany and Plant Sciences
P15016 Extracellular DNA Play a Key Role in Pea Root Tip Resistance to Its Fungal Pathogen
Wen, Fushi-presenter [email protected](a)
VanEtten, Hans (a)
Xiong, Zhongguo (a)
Hawes, Martha C (a)
Plant root tips are immune to most soilborne pathogens. The mechanism for this immunity is just starting to be understood. Here we report
that extracellular DNA (exDNA) is secreted by plant root tips during programmed root border cell production and separation, and that this
exDNA plays a key role in root tip immunity to infection. Biochemical and histochemical assays revealed structural DNA surrounding the pea
root tip and border cells. Several lines of evidence indicate that the exDNA is actively secreted from living border cells and their progenitor
cells during border cell development. Cloning and sequencing analysis revealed that majority components of exDNA are retroelements and
repetitive DNA. When the exDNA is destroyed enzymatically, the resistance of the pea root tip to the fungal pathogen Nectria haematococca
is abolished, and loss of resistance is correlated with rate of DNA digestion. These data are consistent with the hypothesis that exDNA,
together with proteins of the root cap secretome (Wen et al. 2007; Plant Physiol 143:773) are components of a plant defense mechanism
mediated by structurally integrated extracellular DNA and protein complexes. This previously unrecognized phenomenon in plant cells may
reflect a general defense mechanism that is analogous to the mammalian neutrophil extracellular trap (NET), which traps and kills bacteria
(Brinkmann et al. 2004; Science 303:1532).
(a) university of arizona, plant sciences
P15017 A silencing vector for cotton and its response to temperature
Tuttle, John R.-presenter [email protected](a)
Haigler, Candace H. (a)
Robertson, Niki (a)
We developed a vector for virus-induced gene silencing in Gossypium hirsutum using the geminivirus Cotton Leaf Crumple Virus (CLCrV).
The coding sequence of the coat protein was removed and replaced with a polylinker with seven unique sites, driven by the coat protein
promoter. This allowed for the insertion of gene fragments of up to 750-bp for gene silencing or expression of small proteins. We silenced
both the ChlI gene, needed for chlorophyll synthesis, and the PDS gene, needed for carotenoid synthesis using a 500-bp and a 326-bp
cDNA fragment, respectively. Silencing these genes resulted in similar phenotypes except that silencing of PDS was not as extensive,
perhaps due to the smaller size of the cDNA. We investigated the effect of temperature on gene silencing and found that at lower growth
temperatures silencing was delayed but more extensive while higher growth temperatures triggered earlier silencing which diminished to
discrete spots. DNA gel blot hybridization demonstrated that accumulation of the CLCrV:ChlI silencing vector was much greater at the lower
temperatures. Additionally we inserted a 743-bp full length green fluorescent protein gene (GFP) into the polylinker to monitor expression
from the CLCrV vector during the course of infection. Following bombardment, expression of GFP was limited to a few individual cells
throughout the leaf during the first 2-4 days of infection and afterward was strongly evident in the vascular bundles. While GFP expression
was limited to vascular tissues, silencing was observed in all tissues of the leaf and the ovary wall. Later in infection GFP expression was
observed on the surface of developing ovules, suggesting that the CLCrV vector could be useful for understanding cotton fiber gene function
in planta.
(a) North Carolina State University
P15018 Transcriptomic analysis of early responses to salicylic acid in Arabidopsis
Holuigue, Loreto-presenter [email protected](a)
Blanco, Francisca (a)
Herrera, Ariel (a)
Cecchini, Nicolas M (b)
Salinas, Paula
(a)
Alvarez, Maria Elena (b)
Salicylic acid (SA) is a key hormone of stress defenses responses induced by biotrophic pathogens and some abiotic stress in plants.
Although important knowledge concerning SA mechanism has been obtained in the last years, the essential role that this hormone plays in
stress defense is not well understood. To identify early SA-induced genes (SAIGs), expression profiles of wild type and npr1-1 mutant
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Arabidopsis seedlings in response to short treatments with SA were studied by using the Complete Arabidopsis Transcriptome MicroArray
chip. We identified 217 early SAIGs; only a small proportion of them (24; 11%) use the NPR1-independent pathway. Analysis of the
functional categories of these genes support the idea that SA is involved in the recovery of the cell redox balance, in intracellular stress
signaling, in improving pathogen recognition, and in promoting metabolic changes. Expression analysis in response to an avirulent bacterial
pathogen, performed for a selection of these genes, support involvement of early SAIGs in the pathogen-induced defense reaction. Search
for over-represented promoter elements in all SAIGs identified and mechanistic analysis performed for a selection of these genes give us
important clues concerning SA mechanism. Functional promoter analysis for glutaredoxin GRXC9 gene, one of the early SAIGs identified,
allowed us to identify an as-1 element as the main SA-responsive element in this promoter. Supported by grants 1060494 from FondecytCONICYT and 2005-7-186 from CONICYT/SECyT Cooperation Program.
(a) Facultad de Ciencias Biologicas, Universidad Catolica de Chile, Santiago, Chile (b) CIQUIBIC-CONICET, Universidad Nacional de Cordoba,
Cordoba, Argentina
P15019 Functional origin of RPW8-mediated broad-spectrum disease resistance in Arabidopsis
Berkey, Robert-presenter [email protected](a)
Wang, Wenming (a)
Xiao, Shunyuan (a)
http://https://shadygrove.umbi.umd.edu/xiaogroup/
The RPW8 gene isolated from Arabidopsis thaliana confers broad-spectrum disease resistance to Erysiphe spp. that cause powdery mildew
disease on many plant species. Despite having an atypical R protein structure, RPW8 activates a conserved salicylic acid (SA)-dependent
defense pathway leading to hypersensitive cell death in response to powdery mildew challenge. All of the tested Arabidopsis accessions to
date contain three closely linked homologs of RPW8 named HR1, HR2, and HR3 at the same locus that do not seem to contribute to
powdery mildew resistance. Recent evolutionary analyses revealed that RPW8 most likely originated from an HR3-like progenitor gene by
gene duplication and functional diversification. To understand how the resistance function of RPW8 originated, we have recently conducted
genetic analyses and found that 1) overexpression of HR1, HR2 or HR3 individually in susceptible accession Col-0 resulted in enhanced
resistance to powdery mildew; 2) knocking out these genes individually appeared to cause enhanced susceptibility; and 3) unexpectedly
silencing these three genes simultaneously results in enhanced resistance to the pathogen and some developmental phenotypes that
resemble those caused by overexpression of 14-3-3 lambda, whose product interacts with RPW8 in the yeast-two-hybrid. Our genetic data
support the hypothesis that these RPW8 homologs, particularly HR3, may play an important role in basal resistance via the conserved SA
pathway against powdery mildew and perhaps other pathogens and suggest that there may be complicated genetic interaction between
HR1, HR2, HR3 and other defense components for regulation of plant basal resistance.
(a) University of Maryland Biotechnology Institute
P15020 Biogenesis and function of plant viral small RNAs
Harvey, Jagger JW-presenter [email protected](b,a)
Studholme, David (a)
MacLean, Dan (a)
Etherington, Graham
(c)
Baulcombe, David (b,a)
RNA silencing is a plant defence mechanism that targets genomes of invading viruses for degradation. Dicer-like enzymes process the viral
genome into 21-24nt small RNAs (sRNAs) that can affect expression of other genes via Watson-Crick base pairing. In response, viruses have
evolved to encode silencing suppressors as well as sRNA silencing effectors that turn host silencing to their advantage. This study uses
large-scale Illumina sequencing by synthesis to profile sRNAs at early timepoints of Turnip crinkle virus (TCV) infection in susceptible
Arabidopsis. These datasets are being used to identify virus and host sRNA origins and potential targets, differentially expressed virulenceor resistance-related sRNAs, and candidate host- and virus-encoded miRNA genes and prediction of their cognate targets. The sRNA profiles
are also being used for prediction of sRNA-mRNA gene regulation networks in healthy and infected plants. Additionally, viral sRNA hotspot
profiles in infected silencing mutants are being used to elucidate the RNA silencing genes involved in production of several viral sRNA
classes. Any susceptibility- or resistance-related sRNA generating loci or general biogenesis mechanisms identified by this study will shed
new light on the complex role of RNA silencing in plant-virus interactions and may reveal new strategies of engineering disease resistance.
(a) The Sainsbury Laboratory, Norwich UK (b) Dept . of Plant Sciences, University of Cambridge, UK (c) John Innes Centre, Norwich UK
P15021 Analysis of gene expression and viral accumulation in Arabidopsis mutant lines infected with turnip crinkle virus
Donze, Teresa J.-presenter [email protected](a)
Twigg, Paul G. (b)
Morris, T. Jack (a)
We have previously determined that TCV coat protein (CP) interacts with a member of the NAC family of transcription factors called TCVinteracting protein (TIP). Transient co-expression of TIP with TCV CP was shown to prevent TIP‘s normal nuclear localization. A mutant
virus of TCV, called R6A, has a single amino acid replacement in the N-terminal region of the CP which eliminated the interaction between
TIP and viral CP. However, R6A causes more severe symptoms in the susceptible cultivar, Col-0 and breaks resistance in the resistant
cultivar, Dijon-17. In order to better understand the TIP function in the Arabidopsis defense response to TCV, we obtained multiple mutant
lines of Col-0 that are deficient in key components of the known defense pathways: SA, JA, and ET pathways. The mutant plant lines were
inoculated with TCV, R6A, and a mock solution and samples were collected over a time course. Virus transcript accumulation and gene
expression differences between the two viruses and mock inoculums were then monitored to examine the effect of TCV‘s ability to bind TIP
in the mutant lines. TCV was able to accumulate faster than R6A in wt Col-0. Similar results were also observed in the JA and ET defective
lines. However, in the defective SA pathway mutants, differences in TCV and R6A were less evident. This data clearly suggests that, through
its interaction with TIP, TCV directly down regulates the defense response via the SA pathway.
(a) University of Nebraska - Lincoln (b) University of Nebraska - Kearney
P15022 The Arabidopsis pathogen-inducible Patatin-Like Protein (PLP2) lipid acyl hydrolase promotes host cell death and
affects differentially pathogen resistance
La Camera, Sylvain (a)
Geoffroy, Pierrette (a)
Balague, Claudine (b)
Gobel, Cornelia (c)
Legrand, Michel (a)
Roby, Dominique
(b)
Feussner, Ivo (c)
Heitz, Thierry-presenter [email protected](a)
http://ibmp.u-strasbg.fr/
Fatty acid mobilization is an important feature of plant stress responses. Expression profiling revealed that numerous genes encoding
potential lipid acyl hydrolases (LAH) are upregulated upon pathogen attack. These LAHs are predicted to localize in discrete subcellular
compartments to initiate distinct lipid hydrolysis events. An important role anticipated for such enzymes is to provide precursors for the
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biosynthesis of oxylipins acting as potent defense signals (jasmonates), cell death modulators, or phytoalexins. We are exploring the
physiological role of individual members of two LAH families upon biotic stress. PLP2 is a pathogen-inducible, cytoplasmic LAH of the patatin
family with galactolipase and phospholipase activity [La Camera et al. (2005) Plant J. 44, 810]. Unexpectedly, PLP2-silenced plants
displayed enhanced resistance to Botrytis cinerea fungus and to avirulent Pseudomonas syringae bacteria, while plants overexpressing PLP2
were more sensitive to these pathogens. Conversely, opposite effects on resistance to a virus were recorded. Symptomatology and
differential sensitivity of PLP2-modified plants to paraquat suggested that PLP2 promotes host cell death. Global oxylipin profiling revealed
that PLP2 level moderately affects the accumulation of some oxylipins in response to Botrytis. To further investigate the contribution of PLP2
to cell death execution, we crossed PLP2-modified plants with the vad1 lesion mimick mutant that displays spontaneous lesions. In double
mutant progeny, interfering with the expression of PLP2 affected the kinetics and severity of lesion development in vad1 background.
Collectively, the data indicate that PLP2 is an integral component of plant cell death execution machinery, with differential effects on
pathogen resistance.
(a) IBMP-CNRS Universite L. Pasteur (b) Lipm, CNRS-INRA (c) Department of Plant Biochemistry, Goettingen University
P15023 The Bacterial Effector Protein XopN Targets the Plant Receptor-Like Kinase TARK1 to Contribute to Virulence
Aakre, Chris-presenter [email protected](a)
Su, Bessie (a)
Taylor, Kyle (a)
Kim, Jung-Gun (a)
Mudgett, Mary Beth (a)
Bacteria use a conserved type III secretion system to inject effector proteins into their host cells. XopN, an effector protein from the plant
pathogen Xanthomonas campestris pv. vesicatoria (Xcv), was identified in a genetic screen and found to contribute to the growth of Xcv on
both its tomato and pepper hosts. XopN was found to interact with TARK1, a tomato receptor-like kinase, through an LxxLL motif in the Nterminus of XopN. Unexpectedly, knockdown of TARK1 expression results in a brassinosteroid-deficient phenotype in tomato. These plants
have dark green, curled leaves, are mis-regulated for brassinosteroid marker genes, and support better growth of XopN mutant Xcv than
wild-type tomato. These results provide a previously uncharacterized link between the brassinosteroid signaling pathway and pathogen
defense.
(a) Stanford University
P15024 The GLV producing LOX10 governs the outcomes of maize plant-pathogen interactions
Christensen, Shawn A.-presenter [email protected](a)
Meeley, Robert B (b)
Kolomiets, Mike (a)
Maize oxylipins (oxygenated fatty acids), generated by the lipoxygenase (LOX) pathway, have been accredited for their roles in plant
development and defense response to insects, pests, and pathogens. A recent study showed that 9-LOX derived maize oxylipins are
structurally similar to fungal oxylipins and may be hijacked by the fungus and used for conidiation and mycotoxin biosynthesis. To date, 13LOX products (i.e. jasmonic acid and green leafy volatiles) have largely been characterized as defense-related compounds against various
bacteria, fungi, pests and insects. Here, we generated knock-out mutants in the maize 13-LOX, ZmLOX10, to show that specific fungi may
have evolved to use 13-LOX products in order to colonize their host and synthesize mycotoxins. This hypothesis is prompted by our finding
that lox10 mutants, deficient in green leafy volatiles, are more resistant to Aspergillus flavus and Colletotrichum graminicola.
(a) Texas A and M University (b) Crop Genetics Research, Pioneer-A DuPont Company
P15025 Bioengineered maize producing a bacterial quorum-sensing signal for disease resistance to Pantoea stewartii
subsp. stewartii
carter, dawn (a)
shandra, iannucci (a)
horstman, erin (a)
balakrishna, natasha (a)
savka, michael-presenter
[email protected](a)
Pantoea stewartii subsp. stewartii (Pnss) causes Stewarts wilt disease on sweet corn and leaf blight disease on maize by the expression of
the Stewartan capsular polysaccharide (CPS) virulence factor. CPS is responsible for the colonization and biofilm development in xylem
vessels and is regulated by a quorum-sensing (QS) regulon. Pnss utilizes the bacterial cell-to-cell communication signal N- (3-oxohexanoyl)L-homoserine lactone (3-oxo-C6-HSL) to regulate the production of the CPS virulence factor. The expression of yenI from Yersinia
enterocolitica in tobacco and has been shown by us to direct the production of 3-oxo-C6-HSL (Scott et al. 2006. MPMI 19(3): 227-239. In
this work, Hi II maize was bioengineered with yenI to produce the Pnss-cognate 3-oxo-C6-HSL QS signal. YenI-specific sequence was PCR
amplified in HiII RO regenerates and the accumulation of 3-oxo-C6-HSL was confirmed by 3-oxo-C6-HSL signal separation and detection
assays. Signal-producing bioengineered Hi II RO plants have been crossed with pollen from untransformed B73 maize. We are currently
analyzing R1 progeny plants for 3-oxo-C6-HSL signal accumulations and transgene insertions. Pnss will be innoculated on 3-oxo-C6-HSLproducing bioengineered maize and control maize not producing signal. The results will determine if premature expression of the QS
regulon in Pnss by 3-oxo-C6-HSL-producing maize will alter CPS biosynthesis and confer disease resistance.
(a) School of Life Sciences, Department of Biological Sciences, Rochester Institute of Technology
P15026 Antimicrobial Properties of a Class I Neutral Cotton Chitinase
Chlan, Caryl A.-presenter [email protected](a)
Chigarapati, Vijay (a)
Chitinases help defend plants from pathogens. We have isolated a cotton chitinase gene and h determined that it encodes a Class I
chitinase with a predicted molecular weight of 31.5 kD and pI of 6.96. We have purified a cotton chitinase protein by chitin affinity
chromatography that has an apparent molecular weight of 31 kD on one dimensional denaturing SDS polyacrylamide gels. This column
bound fraction consists of three isoelectric isomers, the major form has a pI of 7.0 on focusing gels. This column bound fraction was
analyzed by N-terminal sequence analysis and the amino acid sequence was identical to that predicted from the cloned nucleotide sequence
for the neutral cotton chitinase. The chitin column purified protein was tested for antimicrobial activity in vitro. We also expressed the
cotton neutral chitinase gene in transgenic tobacco and tested for pathogen inhibition in vitro and in vivo. The results from these studies will
be presented.
(a) University Of Louisana at Lafayette
P15027 Tomato resistance to bacterial wilt involves MAPK-, salicylic acid- and jasmonic acid/ethylene-mediated defense
pathways
Cheng, Chiu-Ping-presenter [email protected](a)
Wang, Jaw-Fen (b)
Chen, Yong-Yi (a)
Ho, Fang-I (b)
Lin, Yu-Mei
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(a)
Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops, mainly in tropic, sub-tropic
and warm temperature zones. Planting resistant materials is the most efficient way for controlling the disease. However, information on
plant defense mechanism to systemic infection of this soilborne bacterium is very limited. In this study, we report the establishment of
efficient virus-induced gene silencing (VIGS) system on several Solanaceous species conferring various degrees of resistance/susceptibility
to R. solanacearum. Key parameters involved in the use of VIGS for tomato gene functional study have been analyzed and further
optimized. By employing this system to dissect tomato disease-defense mechanism, the results revealed that MAPK-, salicylic acid- and
jasmonic acid/ethylene-mediated signaling pathways are involved in tomato resistance against bacterial wilt.
(a) National Taiwan University (b) AVRDC-The World Vegetable Center
P15028 Maize genotypes modulate quorum-sensing regulated virulence in Pantoea stewartii subsp. stewartii
Kowsz, Stacy J-presenter [email protected](a)
Savka, Michael (a)
Quorum sensing (QS) is the mechanism by which bacteria communicate through the use of small, diffusible signal molecules, acyl
homoserine lactones (HSLs). QS allows bacteria to derepress or activate genes based on cell density. The primary focus of this work is the
QS system of the bacterial pathogen, Pantoea stewartii subsp. stewartii (Pnss), and causal agent of Stewarts wilt and leaf blight diseases of
sweet and dent corn, respectively. Pnss uses the acyl-homoserine lactone QS signal, 3-oxo-C6-HSL, to derepress expression of its virulence
factor in sweet and dent corn. Sixteen different maize genotypes were selected for examination in regards to production of molecules that
may interfere with Pnss QS. The selected genotypes include progenitor species and maize varieties that are native to various geographical
locations. Aqueous extracts were prepared from leaves of plants, and different QS-dependent bacterial biosensors were used to evaluate
agonist and antagonistic substances from the genotypes. Extracts of genotypes failed to display agonist responses with biosensor strains.
However, extracts showed varied antagonist responses, with the LuxR, 3-oxo-C6-HSL-specific biosensor. An increase in the antagonistic
response was observed with increasing amounts of extract; this corroborates the inference that the extracts contain molecules that inhibit
the 3-oxo-C6-HSL-specific QS response. Zea mays subsp. mays O Odham huuni from Arizona, Z. mays subsp. mays Mandan Yellow Flint
from North Dakota, and Z. mays subsp. parviglumis from Mexico were the genotypes exhibiting the most significant antagonist responses.
This work supports the conclusion that certain genotypes of maize contain molecules that block the QS regulated response of the bacterial
pathogen of corn, Pnss.
(a) Departments of Chemistry and Biological Sciences, Rochester Institute of Technology
P15029 Comparative and Functional Genomic Of Powdery Mildew Resistance In Rosaceae
Jiwan, Derick-presenter [email protected](a)
Yang, Tianbao (a)
Dhingra, Amit (a)
Abbott, Bert (b)
Main, Dorrie (a)
Rosaceae ranks third for its economic importance in the temperate regions of the world. It‘s economically important as it comprises of
various fruits and ornamental plants which are used in our daily life, and recent research has shown the health benefits of consuming these
crops. But its economy is drastically affected due to pre and post harvest loses incurred by various pathogen. One of the major pathogen of
rosaceous crops is powdery mildew. We have been successful in discovering a probable powdery mildew resistance gene in Peach,
Plum, Apricot, Strawberry and Cherry. Interestingly these genes form a different evolutionary group as compared to those from other
well studies plants like Arabidopsis, Maize, Rice and Barely. This gene shows varying expression in different parts of the plants. Further
understanding of its mode of action is helping us to develop functional markers and helping us to develop broad spectrum powdery mildew
resistance, hence resolving the long term issue of pathogen management.
(a) Washington State University (b) Clemson University
P15030 Signaling pathways involved in defense responses of oilseed rape to Leptosphaeria maculans infection
Sasek, Vladimir-presenter [email protected](a,b)
Korbelova, Barbora (a,c)
Burketova, Lenka (a)
http://www.ueb.cas.cz
Leptosphaeria maculans causes one of the most serious diseases of Brassicas called blackleg. Although the genetics of the interaction
between Brassica spp. and L. maculans has been intensively studied for last two decades, very little is known about the signaling
mechanisms participating in the plant defense system. We have investigated activation of defense signaling pathways in Brassica napus
plants upon infection with Leptosphaeria maculans using qPCR expression analysis of marker genes known from Arabidopsis. The primers
were designed on ESTs with high homology to Arabidopsis genes and their specificity to particular signaling pathways was verified by
treatment with chemical inducers sodium salicylate, methyl jasmonate, ethephone, abscisic acid and chitosan. The expression of salicylic
acid (SA) responsive gene PR-1 strongly increased the fourth day after inoculation, whereas no changes in expression of jasmonic acid
responsive gene AOS were detected during the 10 days after inoculation. This is in stark contrast to necrotic lesions observed on the
cotyledons because SA-dependent defenses are effective against biotrophic pathogens. Moreover treatment with sodium salicylate increased
resistance of B. napus plants to infection by L. maculans. This clearly shows that salicylic acid plays a crucial role in this plant-pathogen
interaction.
(a) Institute of Experimental Botany, Academy of Sciences of Czech Republic (b) Department of Crop Protection, Czech University of Life
Sciences (c) Department of Biochemistry and Microbiology, Institute of Chemical Technology
P15031 PAMP-triggered immunity relays on H2O2 production.
Danna, Cristian H-presenter [email protected](a)
Ausubel, Frederick M (a)
An early response to pathogen attack involves recognition of so-called pathogen-associated molecular patterns (PAMPs), molecules that
characterize pathogens or pathogen-infected tissues. PAMPs include pathogen-encoded molecules such as flagellin and host-derived
molecules such as oligogalacturonides (OGs), pectic cell wall fragments released by pathogen-encoded poly-galacturonases. In order to
evaluate PAMPs-triggered bacterial growth inhibition (PTBGI), we have developed a seedlings liquid culture-assay to deliver PAMPs and
measure bacterial growth (Songnuan et al.). In order to validate our system, we used a collection of mutants to measure the bacterial
growth inhibition after treating seedlings with fgl22 or OGs. As previously shown by Zipfel et al., none of the mutants included in this study
were compromised to acquire PAMP-triggered bacterial growth inhibition. Since reverse genetic studies seemed to render no information on
the signaling pathways involved in PTBGI, we explored the role of hormones through a chemical approach. The production of reactive
oxygen species (ROS) is a common early response of plants to pathogen attack and elicitor treatment. In this work we present evidence
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that eliminating H2O2 production after treatment of seedlings with flg22 or OGs suppresses PTBGI. We also discuss the impact of blocking
H2O2 production on PAMP-triggered gene regulation and the role of early response genes on modulating oxidative burst. Songnuan et al
(2007). 2007 Mol. Plant-Microbe Interc. Meeting Book. Zipfel et al. (2004). Nature 428: 764-
(a) Department of Molecular Biology-Massachusetts General Hospital and Department of Genetics -Harvard Medical School
P15032 Tomato rhizosphere microorganisms as a source of antagonists against Fusarium oxysporum f. sp. radicis-
lycopersici
Cordero-Ramirez, Jesus D-presenter [email protected](a)
Apodaca-Sanchez, Miguel A (b)
Maldonado-Mendoza, Ignacio E (a)
http://www.ciidirsinaloa.ipn.mx
Sinaloa state in Mexico produces 23% of Mexico‘s tomato production. The tomato foot and root rot caused by Fusarium oxysporum f. sp.
radicis-lycopersici (Forl) has been reported recently to cause yield losses of up to 50% in the field. The main goal of this work was to create
a germplasm bank of tomato soil microorganisms in order to screen for possible antagonists of Forl. This collection was created by taking
five samples from tomatoes rhizosphere in a crop field. Samples were mixed to create a combined sample to isolate microorganisms by
serial dilutions on LB or PDA medium. Organisms were purified and grown separately, and used to generate a germplasm bank consisting of
758 isolates currently preserved at -70oC. Thirty-four percent of the organisms from this bank (254) were screened against Forl finding
thirteen bacteria and one fungus that showed Forl growth inhibition levels in vitro from 5 to 35%. We have identified 26 organisms by rDNA
sequencing. Two identified bacteria showing antagonism were Bacillus cereus and B. thuringiensis. We have identified three genera of
bacteria as the most abundant ones in the germplasm bank: Bacillus, Brevundimonas and Rheinheimera. The most common bacterial genus
is Bacillus and seven species have been identified so far: B. aquimaris, B. cereus, B. endophyticus, B. firmus, B. megaterium, B. pumilus and
B. thuringiensis. In this work, we will discuss the results of antagonist assays performed in planta using the microorganisms that showed
the best in vitro effect against Forl. This work was kindly supported by Fundacion Produce Sinaloa, CECyT-Sinaloa and the National
Polytechnic Institute (SIP-2006-0317). JDCR has been awarded a graduate and an IPN PIFI fellowship.
(a) CIIDIR-IPN Unidad Sinaloa (b) INIFAP Campo Experimental Valle del Fuerte
P15033 A pathogen-responsive mitogen-activated protein kinase cascade regulates phytoalexin biosynthesis in
Arabidopsis
Liu, Yidong-presenter [email protected](a)
Ren, Dongtao (a,b)
Yang, Kwang-Yeol (a)
Han, Ling (a)
Mao, Guohong
(a)
Glazebrook, Jane (c)
Zhang, Shuqun (a)
Plant recognition of pathogens leads to rapid activation of MPK3 and MPK6, two Arabidopsis mitogen-activated protein kinases (MAPKs), and
their orthologs in other species. Here, we report that synthesis of camalexin, the major phytoalexin in Arabidopsis, is regulated by the
MPK3/MPK6 cascade. Activation of MPK3/MPK6 by expression of active upstream MAPK kinase (MAPKK) or MAPKK kinase (MAPKKK) was
sufficient to induce camalexin synthesis in the absence of pathogen attack. Induction of camalexin in Arabidopsis by Botrytis cinerea was
preceded by MPK3/MPK6 activation, and compromised in mpk3 and mpk6 mutants. Genetic analysis placed the MPK3/MPK6 cascade
upstream of PHYTOALEXIN DEFICIENT 2 (PAD2) and PAD3, but independent or downstream of PAD1 and PAD4. Camalexin induction after
MPK3/MPK6 activation was preceded by rapid and coordinated up-regulation of multiple genes encoding enzymes in the tryptophan (Trp)
biosynthetic pathway, in the conversion of Trp to indole-3-acetaldoxime (IAOx, a branch point between primary and secondary metabolism),
and in the camalexin biosynthetic pathway downstream of IAOx. These results indicate that the MPK3/MPK6 cascade regulates camalexin
synthesis through transcriptional regulation of the biosynthetic genes after pathogen infection. In recent years, the biosynthetic pathways of
a number of phytoalexins have been fully defined. However, the signaling pathway(s) are largely unknown. This study reveals that the
pathogen-responsive MAPK cascade is an important signaling pathway regulating phytoalexin biosynthesis in plants.
(a) Department of Biochemistry and Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211 (b) State Key
Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China (c) Department of Plant Biology and
Center for Microbial and Plant Genomics, University of Minnesota, St. Paul, MN 55108
P15034 Heterologous Biosynthesis of Flavonoid Metabolites and Induction Properties of a Transcription Factor in Maize
Mason, Charles J-presenter [email protected](a)
Ibraheem, Farag (a)
Chopra, Surinder (a)
As increasing acres of land in agriculture moves to maize production, stresses from biotic sources are very likely to increase. An economical
and viable solution to increasing stresses would be improving plant defenses to combat opposing biota. Maize and sorghum are two related
crops, but have different responses upon anthracnose fungal infection. In sorghum, fungal challenged plants are capable of producing
antifungal compounds of the flavonoid class 3-deoxyanthocyanidins. These compounds are produced at primary infection sites and kill the
pathogen and surrounding cells in order to prevent its further colonization of plant tissues. Our laboratory has recently shown that these
compounds are produced via the flavonoid pathway under the control of a myb-transcription factor called yellow seed1 (y1). Interestingly,
maize contains an ortholog of y1 called pericarp color1 (p1). However, p1 is not expressed in vegetative tissue and is not fungal induced like
y1. Thus, we have engineered transgenic maize lines that express either sorghum y1 or over express maize p1 genes. The objectives of this
research were to identify the biochemical changes the y1 and p1 transgenes have in maize and to determine the induction properties of
these transcription factors in fungal challenged plants. Here, we screened the metabolic profiles of eleven maize genotypes for metabolite
variation, visible disease responses over time, and flavonoid accumulation in inoculated plants. Additional data regarding the disease
symptom will be presented. The results from this study help us better understand the induction properties of y1 and p1 in transgenic maize
in response to attacks of microbes.
(a) The Pennsylvania State University
P15035 The gene activation of HRAP, a harpinPss binding protein, is highly associated with hypersensitive response
Feng, Teng-Yung-presenter [email protected](a)
Chen, Cheng-Hsien (b)
Ger, Mang-Jye (c)
Huang, Hsieng-En (a)
http://[email protected]
Certain plants can recognize harpinPss, a proteinaceous elicitor secreted by Pseudomonas syringae pv. syringae, to express hypersensitive
response (HR). However, plant proteins that can directly interact with harpinPss have not been found. HRAP is a plant protein that can
intensify the harpinPss-mediated HR in harpinPss-insensitive plants. In this study, we found that there was a direct interaction between
HRAP and harpinPss in protein-protein interaction assays. This result reveals that HRAP is a harpinPss binding protein. In addition to the
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binding activity, the expression of hrap gene has a connection with harpinPss and bacterial pathogen. The hrap gene expression is
apparently induced in pepper leaves by harpinPss inoculation or incompatible plant-pathogen interactions, but not disease-causing bacterial
pathogen. The temporal and spatial patterns of hrap transcriptional activation in HR-inducing pathogen treatments exhibited a rapid and
localized induction. When the hrap gene expression was blocked by antisense hrap in transient gene expression assays, harpinPss-mediated
HR in the same pepper leaves was reduced significantly. Our results suggest that the harpinPss binding protein HRAP participates in the
early stage of HR establishment in vivo.
(a) Academia Sinica (b) Taipei Medical University (c) National University of Kaoshiung
P15036 Characterization of Chitin Elicitor Receptor Complex in Rice
Shimizu, Takeo-presenter [email protected](a)
Nakano, Takuto (a)
Takamizawa, Daisuke (a)
Kaku, Hanae (a)
Shibuya,
Naoto (a)
CEBiP, chitin elicitor binding protein in rice, plays an important role as a cell surface receptor for chitin elicitor signaling1). However, CEBiP
seemed not to have any functional intracellular domains for signaling and it may require the additional factors for signaling through the
membrane into the cytoplasm. Our recent study also showed that CERK1 (Chitin Elicitor Receptor Kinase 1), a receptor-like kinase with
extracellular LysM domains, is an essential component for chitin elicitor signaling in A. thaliana2). In rice genome, ten receptor-like kinase
genes with LysM domains, named as OsLysM-RLKs, were found. Among these, OsLysM-RLK9 showed the highest homology with CERK1 and
thus analyzed for its function in chitin elicitor signaling in rice. Knock-down transformants of OsLysM-RLK9 showed almost no ROS
generation as well as phytoalexin biosynthesis in response to chitin oligosaccharide elicitor. These results suggested that OsLysM-RLK9 plays
an essential role for chitin elicitor signaling in rice and may form a receptor complex with CEBiP. Blue native PAGE as well as SDSPAGE/western blotting of membrane proteins with/without the pre-treatment with cross-linking agents showed the bands with higher
molecular weight than those of the CEBiP and OsLysM-RLK9 monomers, suggesting the presence of partner protein(s) to form a multimer
with them at the plasma membrane. Yeast two-hybrid analysis showed the positive interaction between CEBiP and OsLysM-RLK9, indicating
the possible receptor complex formation by these two proteins. 1)Kaku et al., PNAS, 103, 11086 (2006), 2)Miya et al., PNAS, 104, 19613
(2007).
(a) Meiji University
P15037 Priming of defense responses in plant cells by bacterial lipopolysaccharides
Desaki, Yoshitake-presenter [email protected](a)
Kobayashi, Daijirou (a)
Molinaro, Antonio (b)
Newman, Mari-Anne
(c)
Yamane, Hisakazu (d)
Nakashita, Hideo (e)
Kaku, Hanae (a)
Shibuya, Naoto (a)
Priming is a phenomenon of plants in which they can more rapidly and extensively mount defense responses to pathogen invasion. This
phenomenon is not only of scientific interest but also important for its potential application in strengthening disease resistance. However,
the mechanism of priming is largely unknown 1). We have previously reported that bacterial lipopolysaccharide (LPS) induces defense
responses associated with PCD in suspension cultured rice cells 2). We recently found that LPS also has a priming activity in our model
system. Furthermore, we found periodate oxidation of LPS abolished the activity to induce defense responses, but little affected the priming
activity. These results suggested that the two activities of LPS might be carried by different portion of LPS molecule. In this poster, we
discuss the mechanism of priming based on the results of phytohormon treatment and the analysis of several mutants. We also use
lipooligosaccharide (LOS), with a defined structure obtained from a mutant bacterium with a compromised LPS biosynthesis 3), to dissect
these activities and identify the structural elements required for them. 1) Conrath, U. et al., MPMI, 19, 1062 (2006). 2)Desaki, Y. et al.,
PCP, 47, 1530 (2006). 3)Silipo, A. Et al, JBC, 280, 33660(2005).
(a) Meiji Univ. (b) Univ. Napoli (c) Univ. Copenhagen (d) Univ. Tokyo (e) Riken
P15038 Proteomic Characterization of Marchitez Manchada disease in Tomato (Licopersicon esculentum)
Nunez-Lopez, Maria Alejandra (a)
Peinado-Guevara, Luz Isela (a,b)
Valdez-Ortiz, Angel (b)
Mendez-Lozano, Jesus (a)
MedinaGodoy, Sergio-presenter [email protected](a)
Recently in Sinaloa State Mexico, it has been detected a new virus infecting tomato plants named: Tomato Apex Necrosis Virus (ToANV,
Turina et al., 2007) which has been associated with the disease Marchitez Manchada (MM) in this crop. The goal of this work is to identify
and characterize through proteomics and mass spectrometry techniques proteins induced by ToANV infection in symptomatic plants with
symptoms of MM in tomato. Positive tomato plants for the ToANV virus through DAS-ELISA assays using antibodies developed by Turina et
al. (2007) were analyzed; those plants were also tested for other viral common diseases in tomatoes in the region resulting negative to
other viruses. Total proteins, extracted from the aerial parts of both healthy and symptomatic plants, were resolved through 2D-SDS-PAGE,
using IPG strips (pH 4-7) and subsequently resolved on the basis of their molecular weight in an SDS-PAGE gel (10%). Western blot was
employed to identify, in 2D-SDS-PAGE gel, proteins belonging to virus or tomato plants. The proteins were identified by MALDI-TOF. Two
proteins of 20 and 26.4 kDa were identified by SDS-PAGE-Western blot on positive plants using anti-ToANV antibodies. The 26.4 kDa
protein (pI 5.7) was detected using 2D-SDS-PAGE-Western blot. MASCOT software revealed 28% coverage identity with a polyprotein
belonging to Ornithogalum Mosaic Virus (OrMV) (ACC No. BAE92900). Most of proteins that matched with the 26.4 kDa identified by
Western blot belong to Potyviridae which are ssRNA viruses and have a conserved region RdRp. Mass spectrometry results show that the
protein identified by antibodies against ToANV has not been previously described. Induced tomato proteins were also identified by mass
spectrometry in the analysis.
(a) CIIDIR-IPN, Unidad Sinaloa, Departamento Agropecuario (b) Universidad Autonoma de Sinaloa
P15039 Coupling Bimolecular Fluorescence Complementation (BiFC) and Fluorescence Activated Cell Sorting (FACS) for
High Throughput Detection of Protein-Protein Interactions in Rice Protoplasts
Saleh, Abdelaty-presenter [email protected](a)
Mitchell, Thomas (b)
Wang, Guo-Liang (b)
Chen, Songbiao (b)
Dean, Ralph
(a)
Recent genome based research has revealed many insights into the nature of host-pathogen interactions. The rice blast pathosystem is
relatively unique in that the genomes of both host and pathogen have been sequenced. Here we report our advances in developing a rice
protoplast system coupled with bimolecular fluorescence complementation (BiFC) to visualize protein-protein interactions directly in living
cells. The BiFC relies on the assembly of a fluorescent protein complex from two split fragments of the yellow or green fluorescent protein
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(YFP or GFP) brought together by interacting proteins. To demonstrate the feasibility of this strategy, we fused the split YFP peptides to rice
and Arabidopsis proteins that are known to interact; specifically the rice spotted leaf11 (SPL11) and its interacting protein (SPIN1) as well as
the Arabidopsis homodimerizing bZIP63 transcription factor. To enhance YFP fluorescence, we tested three promoters, cauliflower mosaic
virus (2X CaMV35), rice actin 1 (ACT-1), and maize ubiquitin-1 (UBI-1), with the 2X CaMV35 yielding superior signal. Fluorescence activated
cell sorting (FACS) of transformed rice protoplasts is being applied to identify cells where bait fungal elicitor proteins interact with tagged
prey plant proteins. This is being accomplished by collecting individual protoplasts and employing single cell PCR and RT-PCR techniques to
detect the interacting prey proteins. Once optimized, the high throughput protoplast system will be adapted to screen for as yet unidentified
fungal elicitors.
(a) Center for Integrated Fungal Research (CIFR), Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
(b) Department of Plant Pathology, Ohio State University, Columbus OH 43210 USA
P15040 Soil bacteria isolated from an agricultural region in Guasave, Sinaloa, Mexico as antagonists to white mold
(Sclerotinia sclerotiorum )
Sotomayor-Garcia, Lucila G-presenter [email protected](a)
Roman-Baez, Ivan A (a)
Valdez-Camacho, Roxana (a)
MaldonadoMendoza, Ignacio E (a)
Lopez-Meyer, Melina (a)
http://www.ciidirsinaloa.ipn.mx
Sclerotinia sclerotiorum is a plant pathogen that affects many important crop species around the world. In Sinaloa, Mexico, S. sclerotiorum
causes white mold in common bean, and it is able to infect most crops during unusually cold and humid winter seasons. S. sclerotiorum
form structures known as sclerotia, which function as resistant structures and remain viable from one crop cycle to the next. When
conditions are proper, sclerotia germinate in the form of mycelium or in the form of apothecia, which are structures that produce
ascospores. Ascospores are disseminated by wind, which is considered to be the main dispersal mechanisms of the disease. The most
common control strategy used by bean producers is the application of synthetic fungicides. Although effective, this strategy may cause
human health and environmental problems in the long run. One alternative to the use of synthetic pesticides is biological control. We have
screened part of a cryopreserved microorganism germplasm bank created from native agricultural soils for antagonism against sclerotia
germination in vitro. This bank is made of 466 bacterial isolates and 292 fungi isolates. So far, we have screened 120 bacterial stains for
inhibition of sclerotia germination, and from those, 16 strains have been found to have such activity in vitro. Two of them, number 40 and
253, which showed the highest growth inhibition effect, have been further characterized. Antagonistic behavior against each developmental
stage of S. sclerotiorum is being studied. Molecular identification is taking place through sequencing of ribosomal DNA to decipher its
taxonomic identity. FINANCING: FOMIX (proyecto 69960), COFAA-IPN, SIP-IPN (20080080), CECYT
(a) CIIDIR-IPN Unidad Sinaloa
P15041 Characterization of gentisic acid as a signal molecule in the defensive response of Solanum lycopersicum―.
Diez-Diaz, Monica-presenter [email protected](a)
Marques, M Carmen (a)
Granell, Antonio (a)
Gadea, Jose (a)
Rodrigo,
Ismael (a)
Conejero, Vicente (a)
Plants cope with both biotic and abiotic stresses by means of a broad array of constitutive and inducible defence strategies, the latter
including, among others, the synthesis of antimicrobial compounds and the accumulation of Pathogenesis Related (PR) proteins. It is well
established that salicylic acid (SA) plays an important role in the activation of the plant defence response. In our laboratory we found that
gentisic acid (GA), a biosynthetic derivative of SA, accumulates at high levels in tomato plants infected with non-necrotizing viroids, viruses
and bacteria. In these infected plants, GA increases more than 150-fold above basal levels, accumulating up to 50-fold more than SA.
Exogenous GA induced the accumulation of the pathogen induced PR proteins: P23, P32, and P34 which were not induced by SA. In order
to further characterize the role of GA, a cDNA library was constructed from GA-treated tomato leaves, and a differential screening (GA vs.
control) was carried out. We identified a collection of clones whose expression is regulated by GA, many of which are defence and stressrelated genes. Furthermore, using the tomato TOM2 microarray, a high throughput transcriptomic approach was developed to compare the
GA and SA signalling role, which has provided information on genes up- and down-regulated by these signal molecules both in early and
late defence responses. From the total of 781 genes regulated by GA, more than 40 genes are differentially regulated with respect to SA,
among them, transcription factors, and defensive proteins such as PR proteins, proteinase inhibitors or polyphenol oxidase. Taken together,
all of our results indicate that GA and SA might act as complementary signals for activation of plant defences.
(a) Instituto de Biologia Molecular y Celular de Plantas
P15042 Differential gene expression analysis in pepper (Capsicum annuum) leaves infected with geminivirus using
pyrosequencing as a cuantitative strategy
Gongora-Castillo, Elsa-presenter [email protected](a)
Ibarra-Laclette, Enrique (a)
Fernandez-Cortes, Araceli (a)
RiveraBustamante, Rafael (a)
The Geminiviruses constitute a large family of plant viruses with circular, single-stranded DNA genome. Pepper golden mosaic virus
(PepGMV) is a geminivirus that infects member of the Solanacea family causing great losses. Recently, a symptom remission system was
characterized in PepGMV-infected pepper plants var. Sonora Anaheim. In this system, plants developed typical symptoms around 10 days
post inoculation (dpi). However, new leaves appearing after 20 dpi present an important decrease of symptom severity. To identify genes
that are differentially expressed in PepGMV-infected (symptomatic or recovered leaves) pepper plants, three cDNA libraries were
constructed. We used the highly quantitative pyrosequencing method (GS20, 454 Life SciencesTM) to obtain 1,838,567 reads (avg. size 100
nt). These reads (pyrosequencing) and 72,975 ESTs (Sanger sequencing) from different cDNA libraries were assembled into 32,738 contigs.
The 454-reads for each condition were aligned against contigs using a sequence alignment tool (BLAST). Differential expressed genes were
identified analyzing BLAST results by Fisher‘s test. When contigs from infected leaves were compared with contigs from control tissue, the
results showed that 120 contigs are overexpressed and 108 repressed in symptomatic tissue, whereas 125 contigs are overexpressed and
116 repressed in the recovered tissue. At least 24% of differential expressed contigs do not align to any reported sequence in NCBI nonredundant polypeptides (nr) database. Contigs which had a high identity with sequences in NCBI nr database were identified and classified
by Gene Ontology hierarchy. Studying these genes will help us to understand viral cycle, symptom development and plant recovery in
pepper natural infection.
(a) Cinvestav Campus Guanajuato
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P15043 The role of cytokinin in plant-nematode interactions
Chronis, Demosthenis-presenter [email protected](a)
Kakimoto, Tatsuo (b)
Mitchum, Melissa G (a)
http://plantsci.missouri.edu/mitchumlab/
Cytokinins are a class of plant hormones that play a major role in plant development. The first step in cytokinin biosynthesis is catalyzed by
adenylate isopentenyltransferase (IPT) followed by a complex series of reactions to produce isopentenyladenine and t-zeatin, the major
forms of active cytokinins in plants. Cytokinin signaling engages through a two-component phosphorelay that involves histidine kinase
receptors (AHK), histidine phosphotransmitters (AHP) and response regulators (ARR). Previous studies have implicated a role for cytokinin in
plant-nematode interactions. Plant-parasitic root-knot nematodes (RKN) and cyst nematodes redifferentiate root cells into specialized
feeding cells within host roots called giant-cells and syncytia, respectively; however, unlike RKN, cyst nematodes do not induce the
subsequent formation of galls. A published report in Lotus showed that gall formation induced by RKN was lower in lines overexpressing
cytokinin oxidase (CKX). CKX is involved in cytokinin degradation indicating that cytokinin may be required for the initial stages of giant-cell
and/or gall formation. Furthermore, we recently published a global analysis of soybean gene expression during cyst nematode-induced
syncytium formation that revealed downregulation of AHKs and upregulation of CKX and A-type ARRs, negative feedback regulators of
cytokinin signaling. In this study, we utilize Arabidopsis as a plant model to dissect the role of cytokinin biosynthesis, signaling, and
response during cyst and RKN infection. Preliminary data from infection of IPT, AHK, and ARR promoter-GUS lines has revealed different
responses of marker genes to cyst and RKN suggesting that the role of cytokinins during the establishment of these two plant-nematode
interactions may differ.
(a) University of Missouri, Division of Plant Sciences and Bond Life Sciences Center, Columbia, Missouri 65211, USA (b) Department of
Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
P15044 Comparison of transcriptome from cankers and healthy stems in American Chestnut (Castanea dentata) and
Chinese Chestnut (Castanea mollisima)
Barakat, Abdelali-presenter [email protected](a)
DiLoreto, Denis S (a)
Baier, Kathleen (b)
Wheeler, Nicolas (c)
Powell, william A
(b)
Sederoff, Ron (c)
Carlson, John E (a)
Comparison of Transcriptome from Cankers and Healthy Stems in American Chestnut (Castanea dentata) and Chinese Chestnut (Castanea
mollisima) American chestnut (Castanea dentata) was devastated by the chestnut blight disease in the beginning of the last century. The
blight is caused by the fungus Cryphonectria parasitica, which infects wounded stem tissue and kills the trees by forming cankers and
girdling the stems. Despite the high economic and ecologic importance of this tree species, genetic studies on American chestnut have been
relatively limited and recently focused on producing blight resistant trees through breeding and genetic engineering. Moreover, the genomic
resources available in NCBI databases for this species were limited to a few hundred of EST sequences prior to this project. To identify
genes involved in resistance to the blight causing fungus, we sequenced the transcriptome from canker margins and healthy stems tissues
collected from American chestnut (blight sensitive) and Chinese chestnut (blight resistant) using ultra high throughput pyrosequencing. This
allowed us to generate 12883 and 15085 unigenes from Castanea mollissima and Castanea dentata respectively. Those unigenes include a
high proportion of genes associated with resistance to stresses and response to biotic stimulus. The unigenesexpressed differentially in
either American or Chinese chestnut canker tissues provide many new candidate genes for resistance to the blight.
(a) The Pennsylvania State University (b) State University of New York, Syracuse (c) North Carolina State University, Raleigh
P15045 Expression analysis of pathogenicity and virulence factors influenced by plant-components in Pseudomonas
syringae pv. phaseolicola NPS3121.
De la Torre-Zavala, Susana-presenter [email protected](a)
Ibarra-Laclette, Enrique (a)
Hernandez-Morales, Alejandro
(a)
Aguilera-Aguirre, Selene (a)
Hernandez-Flores, Jose Luis (a)
Alvarez-Morales, Reynaldo Ariel (a)
http://www.ira.cinvestav.mx
The halo blight disease of beans (Phaseolus vulgaris) is caused by the bacterial pathogen Pseudomonas syringae pv. phaseolicola. On
leaves, symptoms start as small watersoaked spots, which gradually turn necrotic. The lesions remain small and become surrounded by a
wide chlorotic halo. This halo is caused by the effect of phaseolotoxin, a non-host specific toxin produced by the bacteria at low
temperatures (18-20oC). Pod symptoms are similar to those on leaves, starting as watersoaked lesions that eventually produce bacterial
exudates, but chlorotic halo is never observed. To understand how the plant may be differentially influencing the production of
pathogenicity and virulence factors, we analyzed the effect of plant extracts on the genetic expression of this bacteria by probing a genomic
microarray. Differential hybridization was performed using RNA from cultures grown on different sets of conditions : M9 medium at 18oC vs
M9 medium at 28oC, M9 medium vs M9 medium added with bean apoplast liquid, M9 medium vs M9 medium added with bean leaf extract,
M9 medium vs M9 medium added with pod extract. To determine if differential genes are under control of the global regulators GacA and
HrpR, hybridizations with RNA of the wild type bacteria and mutants on gacA and hrpR genes, were also performed. The results showed
that pathogenicity factors such as some putative genes coding for Type III Secretion System Effectors and virulence factors such as genes
coding for phaseolotoxin biosynthesis, clearly showed differential expression when plant extracts were added to the bacterial culture. Some
of these genes were also proved to be under the control of the global regulators GacA and HrpR.
(a) Cinvestav - Campus Guanajuato
P15046 The Arabidopsis thaliana metacaspase AtMCP1b is induced by wounding or pathogen infection.
Rocha-Sosa, Mario-presenter [email protected](a)
Castillo-Olamendi, Luis (a)
Zavariz-Vergara, Antonio (a)
Rueda-Benitez,
Patricia (a)
Porta-Ducoing, Helena (a)
In plants as in animals, programmed cell death (PCD)is a genetically controlled process essential for development and stress responses. In
response to incompatible interactions, the plant rapidly kills cells around the site of infection, this process known as the hypersensitive
response, involves a PCD process which confines pathogen growth. In contrast, in susceptible plant-pathogen interactions, the pathogen
invades the host without a successful defense by the plant. PCD has also been observed in susceptible interactions. Metacaspases, a group
of cysteine-dependent, arginine/lysine-specific proteases, are caspase-like enzymes that participate throughout PCD in plants. An
Arabidopsis cDNA, corresponding to metacaspase AtMCP1b, was isolated from plants infected with the avirulent bacteria Pseudomonas
syringae DC3000 (avrRpm1). AtMCP1b mRNA accumulates also in plants infected with the virulent strain DC3000. The localisation of an
AtMCP1b promoter-GUS fusion was observed in the vascular tissue of transgenic plants. GUS activity increased in response to wounding or
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after an incompatible or a compatible P. syringae infection; however, the response to the virulent pathogen was less intense compared with
the avirulent one. A positive correlation between AtMCP1b mRNA accumulation and cell death was observed in cell cultures treated with
hydrogen peroxide or with staurosporine, a protein kinase inhibitor that induces PCD. Using an AtMCP1b-GFP fusion protein, AtMCP1b was
localized to chloroplasts. Our data strongly support a positive correlation between AtMCP1b gene expression and cell death during
development and pathogenic interactions, and its subcellular localization may indicate an active role for chloroplasts and/or plastids during
cell death processes.
(a) Instituto de Biotecnologia, UNAM
P15047 Defense gene expression in germinating maize embryos to fungal elicitors
Sanchez-Rangel, Diana-presenter [email protected](a)
Gavilanes-Ruiz, Marina (a)
Plasencia, Javier (a)
The events that occur during the plant defense response to the attack by pathogenic microorganisms and associated signaling pathways
have been reported mainly in well-differentiated tissues of dicotyledonous plants or in cell cultures models. However, information about
these defense events during early stages of development, such as germination and establishment of the seedling is scarce. These stages of
development are particularly important because the seeds and seedlings are exposed to pathogens that can survive in the soil or in the
seed. A suitable model to study these events at this particularly stage are excised embryos from dry seed. In order to get some insight on
gene expression at this early stage, we exposed germinating maize embryos to the fungal elicitors xylanase (XYL) and fumonisin B1 (FB1),
and analyzed transcript levels of phenylalanine ammonia lyase (ZmPAL), allene oxide synthase (ZmAOS), pathogenesis-related protein 1,
(ZmPRm) and a PDF-like protein (ZmPDF). XYL caused a dose-dependent increase of the ZmAOS transcript 3 hours post-inoculation (hpi),
and at later times it reached levels comparable to controls. In contrast, ZmPAL transcript levels showed only a slight increase (about 50%).
ZmPRm transcripts showed a dose-dependent increase at all times tested (3 to 24 hpi), whereas ZmPDF transcript increased only at 24 hpi.
FB1, a toxin synthesized by the natural pathogen of maize Fusarium verticillioides, caused a clear increase of the four transcripts analyzed.
Our results showed that the salicylic acid and the jasmonic acid pathways are present in monocots at these early developmental stages and
provide a useful model to study the defense response in germinating maize against the pathogen F. verticillioides. CONACYT 49792 and
50503-Z.
(a) Departamento de Bioquimica
P15048 Pseudomonas syringae induces superoxide formation through long chain bases mediation
Rodriguez-Mejia, Priscila (a)
Olvera-Flores, Maria Teresa de Jesus (a)
Plasencia, Javier (a)
Gavilanes-Ruiz, Marina-presenter
[email protected](a)
One of the main events occurring in the host plant upon a pathogen infection is the fast and massive production of reactive oxygen species
(ROS), which may act as toxic compounds against the intruder and as signals that are transmitted in order to activate molecular defense
pathways. Recently, long chain bases (LCB) have been implicated in the regulation of ROS generation (Shi et al. 2007. Cell Res. 17:1030).
However, the cellular source of ROS remains unknown. This work explores the possibility that NADPH oxidase produces superoxide, the
intermediate in the H2O2 formation regulated by LCB. In order to test this possibility, Arabidopsis thaliana protoplasts were exposed to LCB
and then superoxide formation was measured in the medium. The results showed that FB1, a toxin that produces endogenous accumulation
of LCB, increased 4-fold superoxide formation, while exogenous LCB, 7-fold. When protoplasts were exposed to the avirulent strain
Pseudomonas syringae DC3000 RPM, a 7-fold increase of superoxide was found. These levels were significantly reduced when prior to
bacteria exposure, protoplasts were supplemented with myriocin, an inhibitor of LCB formation. These results suggest that superoxide, one
of the ROS formed during defense against pathogens is regulated by LCB and that is produced by NADPH oxidase. Financed by UNAM (Fac.
Quimica, PAIP 6290-02; DGAPA, PAPIIT IN207806) and CONACYT (55610). PRM is a fellowship recipient from CONACYT (204937)
(a) Dpto. de Bioquimica, Facultad de Quimica, UNAM.
P15049 Biochemical characterization of the Arabidopsis GH3 family member PBS3 involved in salicylic acid-associated
defense responses
Okrent, Rachel A-presenter [email protected](a)
Wildermuth, Mary C (a)
Salicylate (SA, 2-hydroxybenzoate) is a phytohormone best known for its role as a critical mediator of local and systemic plant defense
responses. In response to pathogens such as Pseudomonas syringae, SA is synthesized and activates wide-spread gene expression. In pbs3
mutants of Arabidopsis, induced total SA accumulation is significantly compromised as is SA-dependent gene expression and plant defense
(Nobuta et al. (2007) Plant Physiol 144: 1144-1156). PBS3 is a member of the GH3 family of phytohormone-amino acid conjugating
enzymes with previously unidentified substrate specificity. The reaction catalyzed by the GH3 family occurs in two steps: 1) adenylation to
form an activated AMP-conjugated intermediate and 2) replacement of the AMP to form an amino acid conjugate. A high throughput
adenylation assay was developed to determine in vitro acyl substrates of PBS3 and identify inhibitors of the reaction. This was followed by
assessment of amino acid synthetase activity using these acyl substrates and identification of preferred amino acids. Determination of
kinetic parameters with preferred substrates then allowed for identification of likely physiological substrates of PBS3 facilitating in planta
analyses.
(a) Department of Plant and Microbial Biology, University of California, Berkeley
P15050 The WRKY38 node of Arabidopsis stress signaling
Jones, Alexander M-presenter [email protected](a)
Wildermuth, Mary C (a)
The WRKY transcription factors comprise a eukaryotic superfamily of DNA binding proteins that have undergone a vast expansion in plants.
Due to the expansion of these factors, characterization of function for individual WRKYs has been difficult. However, functional information
for many WRKY factors has become available and roles in regulation of plant defense are widespread among WRKYs. WRKY38 is responsive
to an array of biotic and abiotic stresses and is rapidly induced by the phytohormone salicylic acid. Here we employ microarray analysis in a
WRKY38 T-DNA knock out line and in a line carrying an estradiol inducible WRKY38 transgene to identify the genes regulated by WRKY38.
We also characterize phenotypically the WRKY38 T-DNA mutant, estradiol inducible WRKY38 transgenics and lines carrying a 35S::WRKY38
transgene. Though this analysis did not reveal a role for WRKY38 alone in limiting pathogen growth, further anaylsis suggests WRKY38 does
play a role in moderating osmotic stress and in moderating the toxicity of salicylic acid accumulation. We are continuing our efforts to define
the WRKY38 node of stress signaling through further characterization of the upstream regulation of WRKY38 and identification of the
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WRKY38 dependent components responsible for WRKY38 phenotypes.
(a) UC Berkeley, Dept of Plant and Microbial Biology
P15051 Transgenic cotton expressing a defensin gene for fungal control.
Mckenna, James A-presenter [email protected](a)
Gaspar, Yolanda M (a)
Hinch, Jill M (a)
Lay, Fung T (b)
Anderson,
Marilyn A (b)
Heath, Robyn L (a)
Plants defensins are members of the innate plant defence mechanism. Plant defensins are small, basic, cysteine-rich molecules that have
been shown to inhibit a range of fungi. We have been investigating the potential of the plant defensin (NaD1) to protect plants from fungal
pathogens. NaD1 was isolated from the floral tissues of ornamental tobacco (Nicotiana alata). We have produced transgenic cotton plants
(cv Coker 315) expressing the NaD1 gene and tested the resistance of these plants against the vascular wilt Fungus Fusarium oxysporum f.
sp. vasinfectum. Here we report the initial glasshouse bioassays demonstrating reduced vascular symptoms and improved survival of the
transgenic line D1 compared to the untransformed Coker parent. We also report the results of a field trial which demonstrated three fold
improved survival of transgenic plants, higher numbers of bolls per plants and consequent higher yield.
(a) School of Botany, The University of Melbourne (b) Department of Biochemistry, La Trobe University
P15052 Screening for naturally occurring Bacillus Cereus strains for use in biocontrol of chili wilt
Joe, Darren J.-presenter [email protected](a)
Hanson, Stephen F. (b)
Gutierrez, Guadalupe (b)
Noemi , Moran
(b)
Linda , Liess (b)
Chili peppers throughout New Mexico (NM) are affected by the soil borne pathogen, Phytophthora capsici, a fungus that is the greatest
disease problem facing chili growers today. P. capsici affects the chili peppers by attacking the roots and clogging the vascular system,
resulting in wilting and eventually death. The goal of our research is to build a natural approach to combat this pathogen by searching for
natural bacteria that are antagonistic to the fungus, P. capsici. The use of natural bacteria to battle against P. capsici could benefit the
environment by allowing control of chili wilt without the use of synthetic chemicals. One species of bacteria, Bacillus cereus, has been used
as a biocontrol agent to control Phytophtora that causes diseases in several plant species. Our goal is to identify and isolate Bacillus species
and other natural bacteria to control the fungus P. capsici. To do this, we isolated bacteria from chili roots. Isolations were conducted using
media that were selective for Bacillus. Isolated bacteria were then characterized using polymerase chain reaction and DNA sequence
analysis to identify the genus and species of the bacteria. The bacteria will be tested against P. capsici to determine potential antagonistic
value in controlling the soil borne pathogen. (Supported by NIH grant R25 GM 48998).
(a) San Juan College, New Mexico (b) New Mexico State University, New Mexico
P15053 Bacterial Effectors Target BAK1 and Disrupt MAMP Receptor Signaling Complexes to Impede Plant Innate
Immunity
Shan, Libo-presenter [email protected](a)
Ping, He (a)
Jianming, Li (b)
Antje, Heese (c)
Scott, Peck
(c)
Thorsten, Nurnberger (d)
Gregory, Martin (e)
Jen, Sheen (a)
Bacterial pathogens cause some of the most devastating diseases in plants and humans. The molecular mechanisms underlying bacterial
interception of plant immune responses to promote pathogenicity remain largely unknown. We show that two sequence-distinct type III
effector proteins, AvrPto and AvrPtoB from a ubiquitous plant pathogen Pseudomonas syringae, directly target the receptor-like kinase
BAK1, the shared signaling partner of the flagellin receptor FLS2 and the brassinosteroid receptor BRI1 in Arabidopsis. During infection, this
targeting interferes with the ligand-dependent association of FLS2 and BAK1, and impedes the host responses to diverse microbe-associated
molecular patterns (MAMPs). Mutations in BAK1 diminish signaling and immunity triggered by many of the MAMPs. The identification of
BAK1 as a host target of AvrPto/AvrPtoB virulence uncovers a novel activity of bacterial effectors in blocking signaling initiation from
multiple MAMP receptor complexes, which is uncoupled from the distinct and specific action of AvrPto/AvrPtoB in effector-triggered
immunity mediated by NB-LRR (Nucleotide-Binding-Leucine-Rich-Repeat) immune sensors.
(a) Department of Molecular Biology, Massachusetts General Hospital, and Department of Genetics, Harvard Medical School, Boston, MA,
02114 (b) Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA (c)
Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA (d) Eberhard-Karls-University Tubingen,
Zentrum fur Molekularbiologie der Pflanzen (ZMBP), Auf der Morgenstelle 5, D-72076 Tubingen, Germany (e) Boyce Thompson Institute for
Plant Research, Department of Plant Pathology, Cornell University, Ithaca, New York 14853, USA
P15054 OsWRKY62: A Negative Regulator of Basal and Specific Rice Innate Immunity
Bartley, Laura E.-presenter [email protected](a)
Peng, Ying (a)
Seo, Young-Su (a)
Ronald, Pamela C. (a)
Pathogen perception by receptors encoded in the host genome triggers innate immunity. Detailed knowledge of and control over the
molecular mechanisms of plant immunity is essential for improving agricultural efficiency and meeting the dietary needs of the growing
human population. Our studies of innate immunity in the globally important crop and reference grass system, rice ( Oryza sativa), focus on
signaling by the pathogen recognition receptor, XA21. The receptor-like kinase XA21 confers rice with resistance to most races of the
bacterium Xanthomonas oryzae pv. oryzae (Xoo) and is the best studied of hundreds of similar putative innate immune receptors in rice,
though little is know of its downstream signaling components. A transcription factor in the plant-specific WRKY family, called OsWRKY62,
interacts with the kinase domain of XA21 in yeast two-hybrid screening and in bimolecular fluorescence complementation assays (i.e., splitYFP) in rice cells. Over expression of OsWRKY62 compromises XA21-mediated and basal defense responses to Xoo. Pathogen responsive
genes are down-regulated in rice over expressing OsWRKY62. This repression may be due to the direct action of OsWRKY62, as a GAL4OsWRKY62 chimeric protein possesses transcriptional repressor activity. These data suggests that OsWRKY62 functions as a negative
regulator of immunity and may be inactivated due to its interaction with XA21. On the other hand, expression of OsWRKY62 is increased in
response to Xoo infection, both in XA21 and non-XA21 plants. A model to explain these data is that OsWRKY62 functions to contain immune
responses to appropriate plant tissues.
(a) University of California at Davis
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P16001 Auxin signaling is down-regulated by miRNAs in Phaseolus vulgaris roots inoculated with Rhizobium.
Sanchez, Federico-presenter [email protected](a)
Estrada-Navarrete, Georgina (a)
Pelaez, Pablo (a)
Reyes, Jose L
(a)
Arenas , Catalina (a)
Covarrubias, Alejandra (a)
Quinto, Carmen (a)
Cardenas, Luis (a)
Alvarado-Affantranger, Xochitl
(a)
The symbiotic association between nitrogen-fixing rhizobia and legumes, results in the formation of specialized root organs called nodules.
MicroRNAs (miRNAs) are 20 to 22 nucleotides, non-coding RNAs that regulate mRNAs levels and play important roles in development, stress
and defense responses. miRNAs are well known to inhibit the translation of mRNAs into protein and promote mRNA degradation (Fillipowicz
et al., 2008). Recently, the transcription factor MtHAP2-1, involved in cell differentiation, was identified as target of miR169 in Medicago
truncatula nodule meristematic zones (Combier et al., 2007). Auxin signaling is required for plant defense, growth and development. A plant
miRNA (miR393) contributes to antibacterial resistance by repressing auxin signaling (Navarro et al., 2006). Here, we describe two bean
miRNAs corresponding to miR160 and miR167 families. Both miRNAs were induced in bean roots by auxin. Additionally, pvumiR167 was
induced in bean roots inoculated with Rhizobium. Two ESTs encoding transcriptional factors involved in auxin signaling in P. vulgaris, were
identified to be targeted by a member of the miR167 family. Interestingly, in Arabidopsis miRNA167 regulates female and male reproductive
organs. We will present the symbiotic phenotype of P. vulgaris transgenic roots inoculated with Rhizobium (Estrada et al., 2007), where
pvumiR167 was over-expressed or down-regulated. This work was partially supported by grants IN208407 and CONACYT 42562-Q.
(a) Instituto de Biotecnologia
Session P16 – Plant-Symbiont Interactions
P16001 Auxin signaling is down-regulated by miRNAs in Phaseolus vulgaris roots inoculated with Rhizobium.
Sanchez, Federico-presenter [email protected](a)
Estrada-Navarrete, Georgina (a)
Pelaez, Pablo (a)
Reyes, Jose L
(a)
Arenas , Catalina (a)
Covarrubias, Alejandra (a)
Quinto, Carmen (a)
Cardenas, Luis (a)
Alvarado-Affantranger, Xochitl
(a)
The symbiotic association between nitrogen-fixing rhizobia and legumes, results in the formation of specialized root organs called nodules.
MicroRNAs (miRNAs) are 20 to 22 nucleotides, non-coding RNAs that regulate mRNAs levels and play important roles in development, stress
and defense responses. miRNAs are well known to inhibit the translation of mRNAs into protein and promote mRNA degradation (Fillipowicz
et al., 2008). Recently, the transcription factor MtHAP2-1, involved in cell differentiation, was identified as target of miR169 in Medicago
truncatula nodule meristematic zones (Combier et al., 2007). Auxin signaling is required for plant defense, growth and development. A plant
miRNA (miR393) contributes to antibacterial resistance by repressing auxin signaling (Navarro et al., 2006). Here, we describe two bean
miRNAs corresponding to miR160 and miR167 families. Both miRNAs were induced in bean roots by auxin. Additionally, pvumiR167 was
induced in bean roots inoculated with Rhizobium. Two ESTs encoding transcriptional factors involved in auxin signaling in P. vulgaris, were
identified to be targeted by a member of the miR167 family. Interestingly, in Arabidopsis miRNA167 regulates female and male reproductive
organs. We will present the symbiotic phenotype of P. vulgaris transgenic roots inoculated with Rhizobium (Estrada et al., 2007), where
pvumiR167 was over-expressed or down-regulated. This work was partially supported by grants IN208407 and CONACYT 42562-Q.
(a) Instituto de Biotecnologia
P16002 Silencing a receptor-like kinase in Phaseolus vulgaris transgenic roots arrests nodule development by impairing
vascular bundle formation.
Quinto, Carmen-presenter [email protected](a)
Jauregui, David (a)
Nava, Noreide (a)
Alvarado, Xochitl (a)
Montiel, Jesus
(a)
Rosana, Sanchez (a)
Santana, Olivia (a)
Federico, Sanchez (a)
Legumes can acquire nitrogen through a symbiotic interaction with specific rhizobacteria. Forward genetics and map-based cloning
approaches have identified important actors of the nodulation process in model legumes. Among these players, receptor-like kinases have a
key role. A receptor-like kinase with Leu-rich repeat domains (LRR-RLK) is essential for nodulation: NORK, also called MtDMI2, LjSYMRK or
SrSYMRK. Knocking down the expression of NORK by RNAi reveals to be crucial for epidermal functions and also for the release of rhizobia
from infection threads and symbiosome formation (1, 2). To gain insight into Phaseolus vulgaris receptor-like kinase (PvRLK) functions, we
determined the subcellular localization of the protein by immunolocalization during the nodulation process. The protein is located mostly in
the root central cylinder, in vascular bundles and in the nodule parenchyma. The expression pattern of PvRLK in roots and nodules was also
analyzed by RT-PCR. Transcript levels are increased in 10 and 15 dpi nodules. Transgenic P. vulgaris roots with different down-regulated
PvRLK levels suggest that this kinase plays an essential role in nodule development, in particular in vascular bundle formation. 1. Capoen et
al., 2005 PNAS 102,10369. 2.Limpens et al, 2005 PNAS 102, 10375. Partially supported by a grant from DGAPA, UNAM IN204907 (CQ).
(a) Depto. de Biologia Molecular de Plantas, Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico.
P16003 Regulation of nodule number in Medicago truncatula: sunn, lss, rdn and rae
Schnabel, Elise (a)
Smith, Lucinda (b)
Mukherjee, Arijit (a)
Long, Sharon (b)
Frugoli, Julia-presenter [email protected](a)
The symbiotic association of rhizobia and legumes involves complex molecular signal transduction between the bacteria and the host plant.
Using the model legume Medicago truncatula, we have identified several independent mutations that disrupt the ability of the plant to
regulate nodule number. These supernodulating mutants form 5-10 fold more nodules than the wild type plants. The published sunn
mutation is a mutation in a LRR-receptor kinase that results in short roots and altered auxin flux in addition to supernodulation. We report
genetic interactions of sunn with the as yet uncloned lss locus, as well as the rae mutation, a lesion in the M. truncatula cytokinin receptor
CRE1 gene. When homozygous, mutations in rae suppress the supernodulation phenotype of sunn, but not the short root phenotype. In
contrast, mutations in lss give a supernodulation phenotype when present in a single copy IF the sunn mutation is also present in a single
copy. Alone, lss and sunn behave as recessive mutations and grafting experiments show they control nodule number through a shootderived signal. A fourth supernodulation mutant, rdn, regulates nodulation through a root signal and does not display genetic interactions
with sunn and lss. We have tested nodulation and root length responses of the different mutants to auxin, ethylene, auxin transport
inhibitors, and nitrate; by grafting experiments; and by examination of gene expression. With these data, we have begun to order the
action of the supernodulation genes. We have also identified three putative new mutations that affect the same pathway, suggesting that
the regulation of nodule number is complex and involves multiple genes, plant hormones, and tissues. This work is supported by NSF award
167
No. IOS-0641848.
(a) Clemson University (b) Stanford University
P16004 Fast and transient intracellular ROS changes in living root hair cells responding to specific NFs
Cardenas, Luis-presenter [email protected](a)
Martinez, Adan (a)
Nava, Noreide (a)
Santana, Olivia (a)
Martinez, Nancy
(a)
Barroso, Ma. Luisa (a)
Martinez, Liliana (a)
Sanchez, Federico (a)
Quinto, Carmen (a)
http://www.ibt.unam.mx
The symbiotic interaction between rhizobia and leguminous plants is host specific and induces the formation of nitrogen-fixing root nodules.
Legume roots exude flavonoids that induce the expression of the bacterial nodulation genes, which encode proteins involved in the
synthesis and secretion of signals called Nod factors (NFs). These NFs signal back to the plant root and trigger several responses such as:
ion changes (K+, Cl-, Ca2+, H+), cytoplasmic alkalinization, calcium oscillations, gene expression, etc., leading to bacterial invasion and
nodule formation. The role of reactive oxygen species (ROS) in root-nodule development and metabolism has been extensively studied.
However, there is limited evidence showing ROS changes at the subcellular level during the earliest stages of the interaction between
legumes and rhizobia. Herein, increasing and transient ROS levels were detected at the tip of actively growing root hair cells, within seconds
after addition of Nod factors. This transient response (which lasted up to 3 minutes) is Nod factor specific since chitin oligomers
(pentamers) failed to induce a similar response. When chitosan, a fungal elicitor was used instead, a sustained increasing signal was
observed. Since ROS levels are transiently elevated after NFs perception, we propose that this ROS response is specific of the symbiotic
interaction. Furthermore, we discuss the remarkable spatial and temporal coincidences between ROS and calcium transiently increased
levels observed in root hair cells immediately after NFs perception.
(a) Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico
P16005 Transporters operating at the plant-fungal interface in tall fescue- endophyte symbiotic association; Novel insights
from a nutritional stand point.
Amarasinghe, Ranamalie-presenter [email protected](a)
Hesse, Uljana (b)
Li, Haiquan (a)
Zhao, Patrick (a)
Schardl,
Christopher (b)
Young, Carolyn (a)
Epichloe endophytes are mutualistic fungal symbionts of cool-season grasses (Poaceae), known to confer growth advantages to its host.
However, the molecular basis of the interaction between the endophyte and the grass host remain largely unknown. As a step towards
understanding Grass-Epichloe interactions, we have focused on identifying transporter genes specifically expressed in this symbiotic
association. The genome of Epichloe festucae, a model endophyte, has been sequenced and assembled with a near complete coverage.
Using a bioinformatics approach based on nearest neighbor method to compare against the Transporter Classification Database
(www.tcdb.org), we have identified the putative transporter complement in the Epichloe genome. The same approach was used to analyze
over 17000 transcript assemblies from tall fescue, to identify a set of putative plant transporters. The respective transporter classifications
for the predicted genes were also determined. We utilized a quantitative qRT-PCR approach to compare the expression levels of various
transporter gene families in both plant and fungus. Comparing the expression levels in shoots and roots of endophytic vs non-endophytic
plants, we identified potential symbiosis related plant genes in MFS, POT, and DMT gene families. Comparing In planta expression levels to
those in cultured mycelia, we also identified a number of fungal transporters in families POT, DMT, Amt, MFS, MIP and Trk to be
significantly upregulated in symbiosis. Concurrent expression levels of various transporter gene families provided insights into the nutritional
aspects of the interaction. Further characterization and functional analysis of these transporters will be a substantial contribution towards
understanding plant-fungal interactions.
(a) Samuel Roberts Noble Foundation (b) University of Kentucky
P16006 Border cells of Medicago truncatula are fundamentally important in symbiotic associations with Sinorhizobium
meliloti and Glomus intraradices
Watson, Bonnie S-presenter [email protected](a)
Urbanczyk-Wochniak, Ewa (a)
Moreira, Cesar M (a)
Huhman, David V
(a)
Sumner, Lloyd W (a)
The root tips of many plant species, including legumes, produce thousands of differentiated cells which are separate from the root but
remain appressed to it until released by exposure to water. These cells, termed border cells, are more than by-products of root cap growth.
They provide a biotic boundary or border fundamental in rhizosphere modifications and plant defense. Border cells also appear to play a key
role in plant-symbiont interactions; however, little is known about their participation in these critical plant-microbe associations. Here we
report a systematic approach to evaluate the biochemical differences between border cells, root tips, and whole roots of seedlings of the
model legume Medicago truncatula elicited with Sinorhizobium meliloti and compared to unelicited border cells, root tips and whole roots.
Non-targeted metabolic profiling by UPLC/MS was utilized to probe changes in secondary metabolites. Secondary metabolites found at
higher and statistically significant levels (p<0.05) in border cells included pyrethrin, phenolics, fatty acids, and yet unidentified compounds.
Dihydroxyflavone, the major root flavone in M. truncatula, was found at significantly higher levels in border cells than in root tips or whole
roots. The flavone apigenin, known to be a potent inducer of nod genes in S. meliloti, was also detected at much higher levels in border
cells than in root tips or whole roots. Border cells may also play a key role in associations with the arbuscular mycorrhizal fungus Glomus
intraradices. Upon incubation with border cells, spores of G. intraradices produced a mat of branched hyphae. Work to identify the
fundamental biochemical signal(s) responsible is ongoing and a possible mechanism will be proposed.
(a) The Samuel Roberts Noble Foundation
P16007 Positional cloning of STR, a gene required for arbuscular mycorrhizal (AM) symbiosis in Medicago truncatula
Zhang, Quan-presenter [email protected](a)
Blaylock, Laura A. (a)
Harrison, Maria J. (a)
A mycorrhizal symbiosis mutant, str (stunted arbuscule), was identified from a screen of an EMS mutagenized Medicago truncatula (A17
ecotype) population. Mycorrhizal fungi Glomus versiforme, Glomus intraradices and Gigaspora gigantea are all able to penetrate the roots of
str but arbuscules formed are stunted and development appears to be arrested. Unlike other M. truncatula symbiosis mutants identified to
date, str has a wildtype nodulation phenotype and is therefore an AM symbiosis-specific mutant. str lacks a AM symbiosis-associated growth
response and does not show AM symbiosis-associated increase in shoot phosphate content that is observed in wildtype plants. str was
crossed to M. truncatula A20 ecotype and analysis of 8712 F2 and F3 plants enabled us to map str to a 230kb region. One gene (STR) in
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this region showed a lower transcript level in str relative to wildtype. In str, this gene contains a single nucleotide change which results in a
premature stop codon. The wildtype STR gene successfully complemented the str mutant phenotype and restored wildtype arbuscules, thus
concluding the positional cloning of STR. Details of the positional cloning of STR and its potential role in the AM symbiosis will be discussed.
(a) Boyce Thompson Institute for Plant Research
P16008 Discovery of Medicago truncatula Phosphate Transporters and Involvement in Arbuscular Mycorrhizal Symbiosis
Pumplin, Nathan-presenter [email protected](a)
Gomez, S. Karen (b)
Harrison, Maria J. (b)
http://bti.cornell.edu/
Phosphate (Pi) is a major plant growth-limiting macronutrient. Plants have evolved many strategies for the acquisition of this scarce
nutrient, including the evolution of a suite of phosphate transporters and symbioses with arbuscular mycorrhizal fungi. In the model legume
Medicago truncatula, five Pi transporters have been previously discovered (MtPT1-MtPT5) with different expression patterns and affinities.
One of these, MtPT4, is a low affinity transporter specific to the arbuscular mycorrhizal symbiosis and required for uptake of Pi from the
fungal symbiont. Analysis of the M. truncatula genome has led to the discovery of four additional putative Pi transporters (MtPT6-MtPT9).
Reverse-Transcriptase PCR studies have shown expression of MtPT6 and MtPT9 in a broad range of tissues, and fusion of the MtPT6
promoter to a reporter shows expression in roots restricted to vascular tissue. Expression of MtPT7 could not be detected in any tissue.
MtPT8 expression was only detected in roots colonized by arbuscular mycorrhizal fungi. MtPT8 transcript was also detected in laser-capture
microdissected arbuscules, which is the site of nutrient exchange in the symbiosis. These results suggest that MtPT8 is a second M.
truncatula Pi transporter that may play a specific role in the arbuscular mycorrhizal symbiosis. To ask if MtPT8 is required for the symbiosis,
an RNAi construct targeting MtPT8 has been expressed in WT and mtpt4-1 mutant M. truncatula plants and phenotypic analysis is
underway. Characterization of spatial expression patterns of MtPT8, subcellular localization of MtPT8 protein, and analysis of MtPT8 Pi
transport properties in yeast, have been initiated.
(a) Cornell University (b) Boyce Thompson Institute
P16009 Analysis of leghemoglobin transcript level abundance in tissues of partridge pea
Langenfeld, Katie A-presenter [email protected](a)
Barber, Anna (a)
Twigg, Paul (a)
Partridge pea (Chamaecrista fasciculata) is a native prairie legume that is important in land restoration and increasing the quality of forage
for wildlife. It is also a symbiotic nitrogen-fixing plant that carries out a mutualistic relationship with Rhizobium spp. The result of this
symbiosis is a novel structure called a nodule. Within this, the rhizobia inhabit the plant cells and reduce atmospheric nitrogen to form
ammonium using the enzyme nitrogenase. The activity of this enzyme quickly degrades if exposed to oxygen. To allow the nodule interior
to remain aerobic, leghemoglobin is used to simultaneously lower oxygen levels and to ferry oxygen to the rhizobia. Recently, our lab cloned
the first leghemoglobin cDNA from partridge pea. For this project, we collected various partridge pea tissues and extracted total RNA from
each. We utilized primers made from cDNA sequences to construct semiquantitative RT-PCR assays for leghemoglobin and a control cDNA
(GAPDH) to test our RNAs. We will present our current results. This project was supported by NIH grant P20 RR016469 from the BRIN
program of the National Center for Research Resources and the University of Nebraska-Kearney Department of Biology.
(a) University Of Nebraska-Kearney
P16010 Flavones and flavonols play distinct critical roles during nodulation of Medicago truncatula by Sinorhizobium
meliloti
Zhang, Juan-presenter [email protected](a)
Subramanian, Senthil (a)
Stacey, Gary (b)
Yu, Oliver (a)
Flavonoids play critical roles in legume-rhizobium symbiosis. However, the role of individual flavonoid compounds in this process has not
been clearly established. We silenced different flavonoid biosynthesis enzymes to generate transgenic Medicago truncatula roots with
different flavonoid profiles. Silencing of chalcone synthase, isoflavone synthase, and flavone synthase led to roots deficient for flavonoids,
isoflavonoids and flavones, respectively. When tested for nodulation by Sinorhizobium meliloti, flavonoid-deficient roots had a near complete
loss of nodulation, whereas flavone-deficient roots had reduced nodulation. Isoflavone-deficient roots nodulated normally suggesting that
isoflavones might not play a critical role in M. truncatula nodulation, even though they are the most abundant root flavonoids.
Supplementation of flavone-deficient roots with 7, 4‘-dihydroxyflavone completely restored nodulation. However, the same treatment did
not restore nodulation in flavonoid-deficient roots, suggesting that other non nod gene-inducing flavonoid compounds are also critical to
nodulation. Supplementation of roots with the flavonol kaempferol (an auxin-transport inhibitor) in combination with the use of flavonepretreated S .meliloti cells completely restored nodulation in flavonoid-deficient roots. In addition, S. meliloti cells constitutively producing
Nod factors were able to nodulate flavone-deficient roots, but not flavonoid-deficient roots. These observations indicated that flavones
might act as internal inducers of rhizobial nod genes and flavonols might act as auxin transport regulators during nodulation. Both these
roles of flavonoids are perhaps critical for symbiosis in M. truncatula.
(a) Donald Danforth Plant Science Center, St Louis, MO 63132 (b) University of Missouri, Columbia, MO 65211
P16011 Novel and nodulation-regulated microRNAs in soybean roots
Subramanian, Senthil-presenter [email protected](a)
Fu, Yan (a)
Sunkar, Ramanjulu (b)
Barbazuk, Brad W
(a)
Zhu, Jian-Kang (c)
Yu, Oliver (a)
Small RNAs regulate a number of developmental processes in plants and animals. We sought to identify microRNAs (miRNAs) regulated
during the development of plant root nodules where the majority of biological nitrogen fixation occurs. Root nodules result from symbiotic
interaction between leguminous plants and nitrogen-fixing rhizobia bacteria in the soil. We sequenced ~350000 small RNAs from soybean
roots inoculated with Bradyrhizobium japonicum and identified conserved miRNAs based on similarity to miRNAs known in other plant
species and new miRNAs based on potential hairpin-forming precursors within soybean EST and shotgun genomic sequences. These
bioinformatics analyses identified 60 families of miRNAs of which 40 were novel. A subset of these miRNAs were validated by Northern
analysis and miRNAs differentially responding to B. japonicum inoculation were identified. We also identified putative target genes of the
identified miRNAs and verified in vivo cleavage of a subset of these targets by 5‘-RACE analysis. Using conserved miRNAs as internal
control, we estimated that our analysis identified ~50% of miRNAs in soybean roots. Identification of additional miRNAs using the current
release of soybean genome data is in progress. The conserved miRNA loci and novel miRNAs identified in this study enable investigation of
the role of miRNAs in rhizobial symbiosis.
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(a) Donald Danforth Plant Science Center (b) Department of Biochemistry and Molecular Biology, Oklahoma State University (c) Center for
Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside
P16012 Jasmonic acid influences mycorrhizal colonization in tomato plants by modifying the expression of genes involved
in carbohydrate partitioning
Tejeda-Sartorius, Miriam (a)
Martinez-Gallardo, Norma A. (a)
Martinez de la Vega, Octavio (a)
Delano-Frier, John P.-presenter
[email protected](a)
In this study the involvement of JA on mycorrhizal colonization was analyzed using tomato mutant plants over-expressing prosystemin (PS)
or affected in the synthesis of JA (spr2) inoculated with Glomus fasciculatum. The mycorrhizal colonization was estimated as frequency and
intensity of colonization (F and M %, respectively) and arbuscule abundance (A%) in the root system. Additionally, gene expression and
biochemical assays were performed in roots in order to detect changes in C partitioning or in the defense gene expression profile. F and
M% were similar in PS and wild type (WT) plants, while a higher A% was observed in the former. Interestingly, colonization was
significantly reduced in spr2 plants. The colonization differences observed in WT, PS and spr2 plants were independent of defense gene
expression. In contrast, a correlation between colonization patterns and changes in the expression of some genes involved in sucrose
hydrolysis and transport, cell wall invertase (CWI) activity and mycorrhizal-specific fatty acid content in roots was found. The results suggest
that a possible mechanism by means of which JA might modulate mycorrhizal symbiosis could be through the regulation of C partitioning in
the plant, as supported by the induction of Lin6 and Sus3 (coding for a cell wall invertase and sucrose synthase, respectively) as well as an
increase in the colonization of spr2 plants in response to methyl jasmonate treatment. On the other hand, the high A% observed in PS
plants was not related to the increase of sink strength mediated by Lin6 and Sus3 expression or CWI activity. Thus, the understanding of
the role played by JA in the formation and/or development of arbuscules in these plants merits further research.
(a) CINVESTAV, Campus Guanajuato
P16013 Effect of defoliation and Glomus intraradices inoculation on growth rate of Cedrela odorata L., seedlings
Oros-Ortega, Ivan (a)
Andrade-Torres, Antonio-presenter [email protected](b)
Alonso, Alejandro (c)
Lopez-Collado, Catalino J.
(c)
Perez-Moreno, Jesus (d)
Martinez-Garza, Sandra E. (a)
The spanish or red cedar (Cedrela odorata L.) is a listed timber species and currently very low due to uncontrolled logging, poor natural
regeneration, and the lack of knowledge to produce plant and establish adequate systems plantation. Studies are required to increase the
survival and quality of plants carried field, and this study examines important factors for the proper establishment and early growth of red
cedar seedlings. We evaluated the effect of six treatments (TS) in growth rates (GR) and weight of C. odorata seedlings grown in nursery. A
completely randomized design with a factorial arrangement (2 x 3) was applied, TS consisted of a combination of the factors: percentage of
defoliation (0, 50 and 90) and inoculation of Glomus intraradices (with and without inoculation). The interaction of factors
defoliation/inoculation, showed no significant effects on variables. Only TS with inoculation and 90 defoliation, had the highest fresh weight
of root, but with a significant difference only with respect to TS without inoculation (ANOVA, Tukey, p = 0.0001). Moreover, inoculation had
a significant effect on the GR (height and diameter), as well as in weight (fresh and dry) of stems and leaves (ANOVA, Tukey p = 0.0001).
The red cedar seedlings inoculated with Glomus intraradices had higher GR and more weight, as well as better appearance respect to the
non-inoculated seedlings, regardless of the percentage of defoliation applied.
(a) Graduate Student, Colegio de Postgraduados, Campus Veracruz (b) INBIOTECA, Universidad Veracruzana (c) Colegio de Postgraduados,
Campus Veracruz (d) Colegio de Postgraduados, Montecillo
P16014 Mycorrhiza-induced resistance Sclerotinia sclerotiorum in Phaseolus vulgaris.
Mora-Romero, Guadalupe A-presenter [email protected](a)
Galindo-Flores, Hugo (a)
Felix-Gastelum, Ruben (b)
Lopez-Meyer,
Melina (a)
http://www.ciidirsinaloa.ipn.mx
Arbuscular mycorrhiza fungi (AMF) form a mutualistic association with the majority of higher plants. AMF can efficiently absorb and
transport mineral nutrients, such as phosphorous, from the soil to the host plant in exchange for carbohydrates from the plant. There are
evidences indicating that mycorrhization benefits plants under biotic and abiotic stresses. It has been shown that mycorrhization induces
resistance to root pathogens compared to non-mycorrhized ones. However, much less work has been done regarding mycorrhiza-induced
resistance to shoot pathogens. The aim of this work was to determine the effect of mycorrhization on the induction of resistance of common
bean (Phaselous vulgaris) to the shoot pathogen Sclerotinia sclerotiorum or white mold. Two putative resistant (A55 and Higuera) and one
susceptible (A114) common bean lines were tested. Plants were grown under greenhouse conditions and a detached-leaf assay was set up
to evaluate infection by Sclerotinia sclerotiorum. Our results indicate that putative resistant lines showed no induced additional resistance by
mycorrhization; whereas, putative susceptible line (A114) increased its resistance to this pathogen in colonized plants. These results may
indicate that mycorrhiza-induced resistance to Sclerotinia sclerotiorum is line dependent. Quantitative analysis of expression of genes
putatively involved in the mechanism of resistance induced by mycorrhization is being currently analyzed and will be presented in this work.
The authors thank support from the National Polytechnic Institute (SIP-20080080), COFAA-IPN. MRGA has a graduate fellowship by IPN and
complementary support by IPN-PIFI program.
(a) CIIDIR-IPN Unidad Sinaloa (b) Universidad de Occidente
P16015 Mycorrhiza-induced resistance to Xanthomonas campestris pv. vesicatoria in tomato.
Galindo-Flores, Hugo-presenter [email protected](a)
Mora-Romero, Arlene G. (a)
Felix-Gastelum, Ruben (b)
Lopez-Meyer,
Melina (a)
http://www.ciidirsinaloa.ipn.mx
Arbuscular mycorrhizal (AM) is a symbiotic interaction between a group of soil-borne fungi and more than 80% of terrestrial plants. This
association is mainly known by the nutrient exchange that occurs between the symbionts. AM fungi uptake and transfer mineral nutrients
from soil to the plant, which in return provides the fungus with organic carbon compounds. In addition to nutritional benefits, arbuscular
mycorrhiza symbiosis has proved to confer resistance to root pathogens, and more recently, evidences have emerged suggesting that this
resistance is also effective against shoot pathogens. We have performed experiments to test whether mycorrhized tomato plants, which are
maintained under low phosphate conditions showed an increased resistance to the bacterial pathogen Xanthomonas campestris pv.
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vesicatoria. Tomato plants colonized with the AM fungus Glomus intraradices showed approximately 60% less bacterial lesions than non-
colonized plants. A nutritional effect due to an increase in assimilated phosphate in AM-colonized plants can not explain the increased
resistance observed since non AM-colonized tomatoes supplemented with high phosphate showed the same susceptibility to X. campestris.
Experiments under greenhouse and growth chamber conditions have shown similar results. Quantitative analysis of expression of genes
putatively involved in the mechanism of resistance induced by mycorrhization is being currently analyzed and will be presented in this work.
The authors thank support from the National Polytechnic Institute (SIP-20080080), COFAA-IPN. GFH has a graduate fellowship from IPN
and complementary support by the IPN-PIFI program.
(a) CIIDIR-IPN Unidad Sinaloa (b) Universidad de Occidente
P16016 Characterization of Medicago mutants defective in rhizobial invasion during nodulation.
Dickstein, Rebecca-presenter [email protected](a)
Morris, Viktoriya (a)
Lee, Yi-Ching (a)
Pislariu, Catalina (a)
McKethan, Brandon
(a)
Gann , Janine H. (b)
Sherrier, D. Janine (b)
During symbiotic nitrogen-fixing root nodule development, rhizobia originally outside the plant enter the root by an invasion process,
through plant-derived infection threads that start in curled root hairs and end at newly divided plant cells in the root inner cortex. The
rhizobia are then deposited in the newly divided plant cells within nodule-specific intracellular compartmental symbiosomes through a
process that resembles endocytosis. The nip (numerous infections with phenolics) and sli (sluggish infection) Medicago truncatula mutants
are both defective in rhizobial invasion processes. Both mutants also show defects in lateral root development. The nip mutant contains
hypertrophic infection threads that only rarely release rhizobia, which do not differentiate further. nip shows an apparent defense-like
response and defense related transcripts accumulate in nodulated as well as un-nodulated root systems. In addition to nip, two other nip
alleles have been identified: the more severe allele, latd, by the Harris lab (MPMI 18: 512) and a less severe allele, nip-3, by the Journet lab
(MPMI, In press). To clone the NIP gene, a map-based approach is underway as a collaborative effort. NIP maps to the top of linkage group
1, between markers 146o17 and 23c16. A chromosome walk has defined the physical interval containing NIP. The other mutant, sli, has
different nodulation and lateral root phenotypes. In sli, infection threads reach nodule primordia, but only about 5 % of the nodules develop
past that point. Grafting experiments show that both nip and sli root phenotypes are root controlled. Supported by NSF IOB No.IOB0520728.
(a) University Of North Texas (b) University of Delaware
P16017 Volatile compounds from rhizobacteria that promote growth in Arabidopsis thaliana
Garcia-Juarez, Perla-presenter [email protected](a)
Valencia-Cantero, Eduardo (a)
Lopez-Bucio, Jose (a)
Altamirano-Hernandez,
Josue (a)
Macias-Rodriguez, Lourdes (a)
http://www.iiqb.umich.mx/
Rhizospheric bacteria have an important effect on soil fertility by improving nutrient availability. Also, they may enhance the growth and
development of plant roots and foliage. Recently, it has been found that volatile organic compounds (VOCs) produced by the Plant Growth
Promoting Rhizobacteria (PGPR) Bacillus megaterium (UMCV1, a maize rhizobacteria) promoted the growth and development of Arabidopsis
thaliana seedlings through auxin and ethylene independent pathways. The production of acetoin by B. megaterium suggested a growth
promotion effect mediated by VOCs. The objective of this work was to perform a screen to identify new PGPR isolated from the maize
rizhosphere and to characterize their VOCs, and find new classes of molecules with a plant growth promoting properties. For the analysis of
the promoting effect of PGPR divided petri dishes were used, which contained Murashige Skoog media added with 0.8% phytagar and 1.5%
sucrose. In the distal half, ten seeds of A. thaliana ecotype Col-0 were sown, and the potential PGPR isolates were inoculated at the
proximal half. Primary and lateral root development was recorded for seven consecutive days. At the end of the experiment, plant biomass
was measured. The analysis of VOCs was done by the SPME-GC-MS technique, and the effect of medium composition on VOCs was
analyzed by testing five different media. Our results identify new isolates that promote growth in A. thaliana seedlings, with significant
differences in the number and length of lateral roots, being higher in inoculated plants when compared to non-inoculated controls. The
profile of volatile compounds varies as a function of the bacterial growth phase and culture media used.
(a) Instituto de Investigaciones Quimico Biologicas, Universidad Michoacana de San Nicolas de Hidalgo
P16018 Characterization of the Protease and Molecular Chaperone-Like Activities of Nodulin 41 from Phaseolus vulgaris
Olivares, Juan E-presenter [email protected](a)
Estrada, Georgina (a)
Guillen, Gabriel (a)
Diaz, Claudia (a)
Alvarado, Xochitl
(a)
Sanchez, Federico (a)
The leguminous plants can establish symbiotic associations with soil bacteria of the Rhizobiaceae family, which enables them to use
atmospheric dinitrogen and become independent of soil nitrogen. This complex association begins with an exchange of chemical signals
between both partners and culminates with the formation of new organs on the plant roots, termed root nodules, where the biological
nitrogen fixation takes place. The plant proteins that have specific or enhanced root nodule expression are termed nodulins, and have been
divided in early and late nodulins depending on the time of appearance during root nodule organogenesis and development. We have
purified a 41 kDa protein from Phaseolus vulgaris root nodules and determined, by immunoblot analysis, that it is expressed as a late
nodulin. A cDNA clone was isolated by PCR amplification based on amino acid sequencing and searching of homologous sequences in the
ESTs reported for Phaseolus vulgaris. Its deduced amino acid sequence showed homology with non classical aspartic proteases like nucellin,
CDR1 and CND41, which lack the plant-specific insert (PSI). Preliminary protease activity assays showed that nodulin 41 is able to degrade
casein at acid pH. Another striking feature of this protein is its ability to bind almost any denatured protein, resembling molecular
chaperones. We are now determining if indeed nodulin 41 possess chaperone-like activity and is able to prevent aggregation of denatured
proteins. The optimal pH for nodulin 41 proteolytic activity, as well as how it is affected by the aspartyl protease inhibitor pepstatin and
other compounds (ions, redox reagents, detergents, etc.) will be also determined. The role of this protease-chaperone protein in root
nodule development will be discussed.
(a) Instituto de Biotecnologia-UNAM
P16019 Genome-wide analysis of defensin-like genes in Arabidopsis and Medicago
VandenBosch, Kathryn A.-presenter [email protected](a)
Nallu, Sumitha (a)
Tesfaye, Mesfin (a)
Wang, Lin (a)
Botanga,
Christopher J. (a)
Gomez, S. Karen (b)
Harrison, Maria J. (b)
Glazebrook, Jane (a)
Katagiri, Fumiaki (a)
Silverstein, Kevin A.T.
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(a)
Plants use many defense strategies against pathogens and predators, including the activation of defensin genes to produce antimicrobial
proteins as a front-line safeguard strategy. Using bioinformatics approaches, we have recently shown that genes encoding small, cysteinerich defensin-like proteins (DEFLs) have been grossly under-predicted in plants. Typically, DEFLs number in the hundreds per genome, but
information on expression and function of most DEFL family members is lacking. We developed a custom Affymetrix chip to evaluate DEFL
expression in Arabidopsis thaliana and Medicago truncatula across a wide diversity of developmental stages and in interactions with
microbes. In both species, a small number of DEFLs are constitutively expressed in vegetative tissues or are induced by disease-causing
organisms in roots or leaves. In Arabidopsis, the largest number of DEFLs are expressed in reproductive tissues, while in Medicago the
largest number are induced during nodulation. Using various rhizobium mutants as inocula, we have found that Nod factor is not sufficient
for induction of DEFLs in nodules, and that nodule-specific DEFLs fall into several groups depending on their pattern of induction. We have
identified novel motifs common to the promoters of nodule DEFLs that are predicted to be cis elements directing organ-specific expression.
Results of the microarray experiments will be presented and integrated with MPSS, EST and other available chip data.
(a) University Of Minnesota (b) Boyce Thompson Institute
P16020 Significance of 5` UTR region in the expression of nodule-enhanced calmodulin and carbon and nitrogen
metabolism genes in symbiotic and non-symbiotic tissues of roots in common bean (Phaseolus vulgaris)
Reddy, Pallavolu M.-presenter [email protected](a)
Khandual, Sanghamitra (a)
Alvarado-Affantranger, Xochitl (b)
Silvente,
Sonia (a)
Blanco, Lourdes (a)
Fuentes, Sara (a)
Hernandez, Geiogina (a)
Sanchez, Federico (b)
Lara-Flores, Miguel (a)
In legumes, formation of nitrogen-fixing nodules is accompanied by the induction of a unique set of plant genes, which are termed
―nodulin‖ genes. Nodulin gene expression is regulated by several chemical, microbial and cellular cues. In order to delineate the role of 5`
untranslated region (UTR) region in tissue-specific expression of the nodule-enhanced calmodulin and carbon and nitrogen metabolism
genes, 5` flanking sequences (together with/without 5` UTR) of calmodulin (PvCam1, PvCam2), sucrose synthase (PvSS), PEP carboxylase
(PvPEPc), aspargine synthetase (PvAS) and aspertate aminotransferase (PvAAT2), and two forms of NADH-dependent glutamate synthase
(PvNADH-GOGAT1, PvNADH-GOGAT2) were isolated by genome walking. Sequence analysis revealed the presence of the nodulin-specific
motifs in all eight promoters. The promoter sequences of all aforesaid genes, with and without 5` UTR reflected in the mRNA transcripts,
were fused with enhanced green fluorescent-beta-glucuronidase fusion reporter gene (egfp-uidA), and analyzed for their tissue-specific
expression in symbiotic and non-symbiotic portions of the roots in P. vulgaris. Expression analysis of the promoters studied revealed that
deletion of 5` UTR from PvCam2, PvSS, PvAS, PvAAT and PvNADH-GOGAT1 promoters resulted in a drastic reduction of their expression in
symbiotic (nodule) as well as in non-symbiotic (root) tissues. A close examination of the sequences of 5` UTRs of all these genes revealed a
common feature of the presence of a CT-rich region at close proximity to transcription start site. Results pertaining to the delineation of the
regulatory (cis) elements in the 5` UTR of the promoters that enable enhanced expression of calmodulin, and carbon and nitrogen
metabolism genes will be discussed.
(a) Centro de Ciencias Genomicas - UNAM (b) Instituto de Biotechnologia - UNAM
P16021 Significance of 5` UTR region in the expression of nodule-enhanced calmodulin and carbon and nitrogen
metabolism genes in symbiotic and non-symbiotic tissues of roots in common bean (Phaseolus vulgaris)
Reddy, Pallavolu M-presenter [email protected](a)
Khandual, Sanghamitra (a)
Alvarado-Affantranger, Xochitl (b)
Silvente,
Sonia (a)
Blanco, Lourdes (a)
Fuentes, Sara (a)
Hernandez, Georgina (a)
Sanchez, Federico (b)
Lara-Flores, Miguel (a)
In legumes, formation of nitrogen-fixing nodules is accompanied by the induction of a unique set of plant genes, which are termed
―nodulin‖ genes. Nodulin gene expression is regulated by several chemical, microbial and cellular cues. In order to delineate the role of 5`
untranslated region (UTR) region in tissue-specific expression of the nodule-enhanced calmodulin and carbon and nitrogen metabolism
genes, 5` flanking sequences (together with/without 5` UTR) of calmodulin (PvCam1, PvCam2), sucrose synthase (PvSS), PEP carboxylase
(PvPEPc), aspargine synthetase (PvAS) and aspertate aminotransferase (PvAAT2), and two forms of NADH-dependent glutamate synthase
(PvNADH-GOGAT1, PvNADH-GOGAT2) were isolated by genome walking. Sequence analysis revealed the presence of the nodulin-specific
motifs in all eight promoters. The promoter sequences of all aforesaid genes, with and without 5` UTR reflected in the mRNA transcripts,
were fused with enhanced green fluorescent-β-glucuronidase fusion reporter gene (egfp-uidA), and analyzed for their tissue-specific
expression in symbiotic and non-symbiotic portions of the roots in P. vulgaris. Expression analysis of the promoters studied revealed that
deletion of 5` UTR from PvCam2, PvSS, PvAS, PvAAT and PvNADH-GOGAT1 promoters resulted in a drastic reduction of their expression in
symbiotic (nodule) as well as in non-symbiotic (root) tissues. A close examination of the sequences of 5` UTRs of all these genes revealed a
common feature of the presence of a CT-rich region at close proximity to transcription start site. Results pertaining to the delineation of the
regulatory (cis) elements in the 5` UTR of the promoters that enable enhanced expression of calmodulin, and carbon and nitrogen
metabolism genes will be discussed.
(a) Centro de Ciencias Genomicas - UNAM (b) Instituto de Biotechnologia - UNAM
P16022 Establishment of in vitro production system of the Gastrodia elata immature tubers followed by symbiotic seed
germination
Park, Eung-Jun-presenter [email protected](a)
Ahn, Jin Kwon (a)
Lee, Wi Young (a)
Kim, Seung Taek (a)
Gastrodia elata, which is an achlorophyllous orchid plant, must establish the symbiotic relationships with beneficial fungi, depending on its
developmental stages such as seed germination and vegetative growth. A major problem occurring in the field production system of
Gastrodia elata is the degeneration of tubers caused by successive asexual propagation. Keep this in mind, we first self-or cross-pollinated
over 7,000 flowers and germinated the seeds lacking endosperm on the medium containing hardwood leaves infected with Mycena spp.
Cytological observation revealed that the fungal hyphae covered a few layers of epidermal cells at the basal area while no trace of hyphae
was shown at the meristem tissues. Histochemical analysis also showed that starch grains in the epidermal cell layers were much smaller
than those in the endodermic cell layers, indicating that starch degradation in the epidermal cells have direct relationship with hyphae
infection of Mycena spp. Subsequently, the protocorms were inoculated with 26 fungal isolates, which belonged to seven Armillaria species.
Armillaria gallica was the best for in vitro growth of the protocorm; the protocorms became larger immature tubers (2 ~ 4 cm in length)
that can be directly used for the actual field production of Gastrodia elata tubers, within four months. In conclusion, this study established
the in vitro production system of Gastrodia elata immature tubers via symbiotic seed germination and subsequent protocorm growth. We
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PB 2008
therefore suggest that this system is an efficient way not only to avoid the tuber degeneration but also for the mass and rapid production of
the immature tubers.
(a) Korea Forest Research Institute
Session P17 – Cell Walls
P17001 The REDUCED RESIDUAL ARABINOSE gene family encodes putative arabinosyltransferases located in the Golgi
apparatus
Egelund, Jack-presenter [email protected](a)
Jensen, Niels Bjerg (b)
Pauly, Markus (c)
Willats, William (a)
Three putative arabinosyltransferases in Arabidopsis thaliana, designated REDUCED RESIDUAL ARABINOSE -1, -2 and -3 (RRA1, RRA2 and
RRA3), have been characterized. It has recently been demonstrated that insertional mutants in RRA1 and RRA2 have an approximately 20%
reduction in the arabinose content of the residual cell wall pellet after enzymatic removal of pectic and xyloglucan polysaccharides. This
preliminary data suggests that both these genes may encode arabinosyltransferases. The RRA genes are classified in CAZy GT-family-77
and are phylogenetically related to putative glycosyltranferases of Chlamydomonas reinhardtii. CAZy GT-family-77 currently contains only
four glycosyltransferases with confirmed biochemical activity - three (1,3)-α-D-xylosyltransferase from Arabidopsis thaliana and one (1,3)-αD-galactosyltransferase from Dictyostelium discoideum. In our current work we have investigated the sub-cellular localization of RRA1,
RRA2 and a homologous gene RRA3, using a YFP fusion protein approach. We present data showing that the RRA1, 2 and 3 fusion proteins
all display fluorescence in small vesicles similar to those of other Golgi-localized enzymes. The fluorescent structures were therefore
investigated further by treatment with Brefeldin A, a lipophilic fungal toxin known to block vesicular transport in the secretory pathway, and
vesiculation and disassembly of the Golgi apparatus. Finally we substantiate these findings using a Golgi marker protein. In conclusion, both
the Brefeldin A and the Golgi marker data are consistent with targeting to the Golgi apparatus, consistent with RRA gene products encoding
arabinosyltransferases involved in arabinosylation of cell wall glycans.
(a) Department of Molecular Biology, University of Copenhagen, Ole Maaloes Vej 5, 2200 Copenhagen, Denmark (b) Plant Biochemistry
Laboratory, Department of Plant Biology, Faculty of Life, University of Copenhagen, Denmark (c) MSU-DOE Plant Research Laboratory,
Michigan State University, East Lansing, MI 48824-1312, USA
P17002 A proteomic approach to identify and characterize the cellulose synthase complex and the proteins associated to
membrane microdomains in Poplar
Fugelstad, Johanna K. E.-presenter [email protected](a)
Malm, Erik (a)
Sundqvist, Gustav (a)
Nilsson, Robert (b)
Ohlsson, Anna
(a)
Wingsle, Gunnar (b)
Sundberg, Bjorn (b)
Bulone, Vincent (a)
http://www.biotech.kth.se/woodbiotechnology/
Cellulose is of great importance as a raw material for different industrial applications, such as pulp and paper and bioethanol production. It
is also the main structural and load-bearing component of plant cell walls. The mechanisms of cellulose synthesis are poorly understood,
which exerts a limitation in the possibilities of future exploitation of cellulose from plant biomass. Our objective is to better understand the
cellulose synthesis process in plants. In this work, cell suspension cultures of the sequenced Populus trichocarpa genotype Nisqually-1 have
been used to isolate detergent-resistant microdomains from the plasma membrane by two-phase partitioning and flotation in a linear
sucrose gradient. Individual proteins were identified using a proteomic approach based on SDS-PAGE and 2D-PAGE combined with
immunochemistry and mass spectrometry. In parallel, glucan synthase activities of the isolated microdomains were assayed by measuring
the incorporation of 14C-labelled glucose into ethanol-insoluble polysaccharides, and characterization of the corresponding in vitro products
was achieved. Preliminary results show that microdomains contain glucan synthase activities. Some proteins relevant to cellulose synthesis
have been identified. Work is ongoing to identify and determine the function of more candidates in the cellulose synthase complex and
other relevant proteins.
(a) KTH Biotechnology (b) Umea Plant Science Center
P17003 Stress relaxation in the walls of normal growing plant cells occurs by a Loss of Stability mechanism
Lintilhac, Philip M-presenter [email protected](a)
Wei, Chunfang (b)
http://www.uvm.edu/~plantbio/?Page=faculty.php&NAME=lintilhac
Traditionally, plant cell wall materials have been assumed to relax during turgor-driven growth by a mechanism which depends on viscoelastic or visco-plastic extension. This behavior can be demonstrated in vitro, by applying relatively sudden tensile loads to excised cell wall
fragments. Under these conditions the induced stresses in the wall can be shown to decay exponentially over time, a characteristic which
typically reflects visco-elastic behavior. However,under carefully controlled conditions which accurately reflect the very gradual loadings
seen during normal cell growth, the log-linear time dependency of stress relaxation is not seen. Rather, a gradual loading regime results in
a continuously decreasing slope of the force/extension curve, with failure occurring only at zero slope, a signature feature of Loss of
Stability behavior. This study reveals an entirely new model plant cell wall stress relaxation and leads to new interpretive possibilities for
understanding plant cell growth in general.
(a) The University Of Vermont (b) Guanxi National University
P17004 Genomics of cell wall biogenesis
Wilkins, Thea A-presenter [email protected](a)
Franklin, Scott R (a)
May, Gregory D (b)
Developing cotton fibers offer a unique single-celled model system for investigating the genetic mechanisms underlying biogenesis of plant
cell walls. Biogenesis of a dicot primary (PCW) and thick cellulosic secondary cell wall (SCW) is temporally regulated by developmental
switches that control dynamic re-modeling of the cotton fiber transcriptome. Coupling of Solexa next-generation sequencing technologies,
transcriptome and metabolic profiling, and comparative genomics is providing novel insight into the mechanisms that control cellulose
synthesis as a step towards the genetic enhancement of fiber and bioenergy crops. A significant number of the more than 1000 cotton
SCW-specific transcripts identified as candidate genes of interest are also mis-expressed in a fiber cellulose-deficient mutant. A subset of
these candidate genes, many of which encode genes of unknown function, are shared in common with the poplar and Arabidopsis
genomes, some of which have been shown to encode novel cell wall-related genes based on mutant analysis. Using this integrated genomic
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approach is rapidly advancing our understanding of the genetic mechanisms that control cell wall biogenesis, and paves the way for the
genetic enhancement of cellulose content and cotton fiber quality.
(a) Texas Tech University (b) National Center for Genome Resources
P17005 Transcriptional analysis of cell cycle putative pectin methylesterases in Arabidopsis thaliana suspension cultures
Qouta , Lolita (a)
Nimmo , Hugh (a)
Brett , Chris (a)
Baydoun , Elias -presenter [email protected](b)
Homogalacturonans (HGs) are linear polymers composed of 1--4-linked α-D-galacturonic acid (GalA) residues. They are known to be
abundant in areas critical for cell-cell adhesion like middle lamellae and tricellular junctions. HGs are typically deposited into the apoplasm in
a highly methyl esterified form and can be subsequently de-esterified by wall-based pectin methyl esterases (PMEs. Arabidopsis thaliana has
66 open reading frames that have been annotated as PMEs.Ten cell cycle related PMEs namely At4g02330, At1g02810, At2g26440,
At2g47550, At5g47500, At4g12390, At1g76160, At4g12420, At4g22010 and At4g25240, were annotated to be expressed at one or more
phases of the cell cycle of synchronized Arabidopsis thaliana suspension cultures. Sequence and phylogenetic analysis revealed that only
five of these genes could be PMEs. The genes At4g02330, At1g02810, At2g26440, and At2g47550 were thought to be of type II PMEs
which has a pre-pro-catalytic domains and At5g47500 is a type I PME that lack the pro-region. The amino acid sequence of At4g12390
showed similarities with the N-terminal pro-peptides of plant PME and invertase inhibitors. The expression of several PME genes was studied
in suspension cultures of Arabidopsis thaliana synchronised using aphidicolin. Semi-quantitative PCR experiments showed that the
expression of At5g47500 transcript was always detected during M phase of the cell cycle. The rest of the genes failed to show consistent
patterns of expression. Northern blots revealed that mRNA coding for At5g47500 decreases during S and G2 phases and accumulates during
the M phase of the cell cycle. Our results suggest that this PME isoform is involved in the modulations of cell walls as the cells are going
through division and cytokinesis.
(a) University of Glasgow, Glasgow, United Kindom (b) American University of Beirut, Beirut, Lebanon
P17006 AU rich regions and DST sequences, highly conserved among plant SAUR genes, apparently regulate the stability of
Zinnia elegans peroxidase mRNAs
Ros Barcelo, Alfonso-presenter [email protected](a)
Gabaldon, Carlos (a)
Gomez Ros, Laura V. (a)
Lopez Serrano, Matias
(a)
Zapata, Jose M. (b)
Cuello, Juan (a)
The Zinnia elegans basic peroxidase (ZePrx), an auxin inducible protein, is putatively encoded by at least two mRNAs. Although virtually
nothing is known about the mechanism of mRNA degradation in plants, considerable evidence has been accumulating that indicates that
mRNA stability contributes to the control of the expression of many plant genes, and that the instability may be determined by AU rich
regions contained in the untranslated regions (UTRs), and by several sequences located downstream of transcriptional start sites (DST)
located either in 3‗UTRs or 5‗UTRs of the mRNAs. ZePrx mRNAs contain at least five destabilization (AU-rich) motifs of the type, UUUUUU,
AUUUUG, AAUUUU, UUUUGU and GUUUUG, located in the 5‗UTRs and the open reading frame (ORF). Besides, ZePrx mRNAs contain DSTs
analogous to the DSTs contained in the highly instable auxin-inducible small auxin-up RNAs (SAUR) of soybean. The presence of these
motifs apparently regulate the stability of ZePrx mRNAs. This work was supported by a grant from the MEC (BFU2006-11577/BFI)-FEDER.
(a) Universidad de Murcia (b) University of Alcala
P17007 Auxins/cytokinins and gibberellins/brassinosteroids have opposite effects in the hormonal regulation of the basic
peroxidase isoenzyme from Zinnia elegans
Lopez Nunez-Flores, Maria Josefa-presenter [email protected](a)
Gomez Ros, Laura (a)
Esteban Carrasco, Alberto (b)
Novo Uzal ,
Esther (c)
Gutierrez, Jorge (c)
Diaz, Jose (c)
Sottomayor, Mariana (d)
Cuello, Juan (a)
Ros Barcelo, Alfonso (a)
Xylem differentiation in plants is under strict hormonal regulation. Auxins and cytokinins, together with gibberellins and brassinosteroids,
appear to be the main hormones controlling vascular differentiation. In this report, we study the effect of these hormones on the basic
peroxidase isoenzyme from Zinnia elegans (ZePrx), an enzyme involved in lignin biosynthesis. Results showed that auxins and cytokinins
induce ZePrx, in a similar way to their capacity to induce secondary growth (metaxylem differentiation). On the other hand, exogenous
application of gibberellins and brassinosteroids reduces the levels of ZePrx, counteracting the positive effect of auxins and cytokinins. This
differential hormonal response is supported by the analysis of the ZePrx promoter, which contains cis-elements responsive to these
hormones. Possible cross-talks between these hormones, and their relations with xylem differentiation and lignification are discussed. This
work was supported by a grant from the MEC (BFU2006-11577/BFI)-FEDER. JG holds a fellowship (FPI) from the MCYT.
(a) University of Murcia (b) University of Alcala (c) University of La Coruna (d) University of Porto
P17008 Proteins differentially expressed in developning xylem of Eucalyptus grandis during tension wood formation
Salvato, Fernanda-presenter [email protected](a)
Camargo, Eduardo L.O. (a)
Boaretto, Luis F (a)
Bonatto, Jose M. C.
(a)
Andrade, Alexander (a)
Bragatto, Juliano (a)
Labate, Carlos A (a)
Stems and branches of angiosperms trees form tension wood (TW) when exposed to a gravitational stimulus. TW is characterized by
important ultrastructural changes like the deposition of a gelatinous cell wall layer (G layer) that consists of highly crystalline cellulose. Due
to its characteristics, tension wood is an attractive experimental system to study wood formation. Trees of 1.8 year-old E. grandis were bent
for 15 days to stimulate tension wood formation.With the aim of identifying the differentially expressed proteins in tension wood, proteins
were extracted from differentiating xylem in the upper side of the leaning stem. These proteins were separated by two-dimensional
polyacrylamide gel electrophoresis and identified by LC-MS/MS. The first dimension was done using IPG strips 4-7 pH gradient, and the
second dimension by homogeneous 12.5% PAGE. Triplicates of the gels were run and stained with Coomassie G-250 to detect the proteins.
Gels were scanned using a UTA-1100 scanner and Labscan V.5 software and image analysis were performed automaticallyusing Image
Master Elite v 3.0 software (GE Amershan Bioscience). The analisys of protein profile detected 1154 spots in tension wood and 776 spots in
normal wood. A comparison between normal and tension wood showed 233 proteins that displayed significant change in expression, 360
spots were only observed in tension and 96 spots only in normal wood.The differentiating proteins analyzed were excised from each gel and
after triptic digestion, MS analysis were conducted. Peptides mixtures were sequenced by on line chromatography using Cap-LC coupled to
a Q-TOF Ultima API mass spectrometer (Waters).
(a) Laboratorio Max Feffer de Genetica de Plantas - Escola Superior de Agricultura Luiz de Queiroz - Universidade de Sao Paulo
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PB 2008
P17009 Arabidopsis UDP-sugar pyrophosphorylase: evidence for two isoforms
Gronwald, John W.-presenter [email protected](a,b)
Miller, Susan S. (a)
Vance, Carroll P. (a,b)
Arabidopsis UDP-sugar pyrophosphorylase (AtUSP, EC 2.7.7.64) is a broad substrate pyrophosphorylase that exhibits activity with GlcA-1-P,
Gal-1-P and Glc-1-P. AtUSP, a single gene in Arabidopsis, is widely expressed in tissues. Although USP exhibits activity with GlcA-1-P, it is
not clear whether USP is the only pyrophosphorylase exhibiting this activity and hence the pyrophosphorylase that catalyzes the terminal
step of the myo-inositol oxidation pathway. A polyclonal antibody was generated to Arabidopsis recombinant USP and used in immunoblots
and immunoprecipitation assays to further characterize the enzyme. Immunoblots demonstrated the presence of two USP isoforms of
approximately 70 kDa (USP1) and 66 kDa (USP2) in crude extracts of Arabidopsis tissues. The 66 kDa isoform was not the result of
proteolytic cleavage of USP1 during extraction. Trypsin digestion of bands on SDS gels corresponding to the location of the two isoforms
followed by tandem mass spectrometry confirmed that USP peptides were present in both bands. Both USP isoforms were detected in the
cytosol as determined by immunoblots of cellular fractions obtained by differential centrifugation. However, USP1 was also detected in the
microsomal fraction. Immunoprecipitation assays demonstrated that AtUSP antibodies removed USP activity (pyrophosphorolysis reaction)
measured in floret extracts. These results indicate that USP is the only pyrophosphorylase that utilizes UDP-GlcA as a substrate and suggest
that it serves as the terminal enzyme of the myo-inositol oxidation pathway.
(a) Plant Science Research Unit, USDA-ARS (b) Department of Agronomy & Plant Genetics, University of Minnesota
P17010 Characterization of the functional domains of a glycoside hydrolase from family 17 highly expressed during wood
formation in hybrid aspen
Brown, Christian J.-L.-presenter [email protected](a)
Kallas, Asa (a)
Bulone, Vincent (a)
Teeri, Tuula T. (a)
http://www.biomime.org/
Carbohydrate-binding modules (CBM) are important functional domains in carbohydrate-active enzymes. The CBMs so far characterized are
primarily from bacteria or fungi,and information on CBMs from plant enzymes is limited. However,the majority of CBMs discovered in family
CBM43 (formerly X8) originate from plants. Bioinformatic analysis of 225 CBM43 sequences from plant and fungi shows that the CBMs in
this family occur as isolated proteins, or are linked to GPI anchors or to catalytic modules of glycoside hydrolases (GH) from families 5, 17
or 72. Furthermore, some of the GH17 catalytic modules were found to be associated to two copies of CBM43 in tandem, or to a GPI anchor
and a CBM43. Different relative levels of expression were observed in hybrid aspen tissues for genes encoding the different modular
arrangements, suggesting different roles during plant development. Transcript profiling in hybrid aspen ( Populus tremula x tremuloides)
revealed that a gene encoding a putative β-(1,3)- glucanase from family 17 is highly expressed during wood formation (Aspeborg et al.,
2005). The C-terminal domain of this protein is similar to a family 43 CBM. Different constructs have been made to express in E. coli the
putative catalytic domain and the corresponding CBM43. This presentation will describe the expression, purification and preliminary
characterization of these functional domains.
(a) Swedish Center for Biomimetic Fiber Engineering, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
P17011 Investigating cell wall gene functions through analysis of Mu transposon knockout alleles
Hunter, Charles T-presenter [email protected](a)
Restrepo, Christian R (a)
Ibekwe, Emeka (a)
McCarty, Don R (a)
Koch, Karen R
(a)
The Cellulose Synthase-Like (CSL) genes represent about 70% of the Cellulose Synthase Superfamily. They are hypothesized to encode
enzymes that synthesize the backbones of the various hemicelluloses found in plant cell walls. This role has been demonstrated for a
number of the CSL gene families, including the CSLA (mannan synthase) and CSLF (mixed-linked glucan synthase) families. Hemicelluloses
are thought to function primarily by cross-linking and stabilizing cellulose microfibrils, thereby regulating cell wall growth and expansion.
Therefore, these polysaccharides represent candidates for influencing cell wall recalcitrance to physical, chemical, and enzymatic
breakdown, a process necessary for conversion of lignocellulosic material into ethanol. Maize genetics has long employed the natural
abundance of transposable elements for gene identification and characterization. In this project, reverse genetics utilizing the UniformMu
maize population (www.uniformmu.org) has been employed to identify Mu transpson insertions in specific cell-wall related genes. Maize
represents an excellent model system for investigating cell-wall dynamics for biomass and ethanol production. The grass species share the
unique Type II cell wall, which contains different polysaccharides, organization, and regulation than the cell walls of most other plants.
Here, a number of Mu transposon-induced knockout mutations of individual CSL genes are analyzed. Specifically, insertions in various CSLA
and CSLD family members are examined for phenotypic changes in plant architecture and growth caused by Mu-induced mutations. Cell
wall compositional analysis of these mutants is currently underway.
(a) University of Florida
P17012 Fluorescent staining of pollen tube cell walls by Propidium Iodide
Winship, Lawrence J-presenter [email protected](a)
McKenna, Sylvester T. (b)
Lubeck, Eric S (a)
Hepler, Peter K (c)
http://www.hampshire.edu
Propidium Iodide (PI, 30 μM) applied to living lily and tobacco pollen tubes caused fluorescence along the entire tube wall with a particularly
strong signal at the growing tip. PI in the medium had no effect on growth rate over several hours. PI bound rapidly in lily (minutes for full
intensity) and more slowly (tens of minutes) in tobacco. In lily and tobacco pollen tubes oscillating in growth rate, fluorescence at the tube
tip oscillated with the same period as growth and was phase shifted ahead of the growth maximum. In lily pollen tubes with obviously
thickened cell walls PI fluorescence was highest where the wall was thickest (DIC). The fluorescence image precisely overlapped the image
of the cell wall. PI does not appear to be covalently bound since fluorescence rapidly decreased when PI was washed out. Calcium affects
the intensity of the PI signal. When [Ca++] was shifted upwards PI signal intensity in the wall rapidly decreased. Full intensity was
recovered by returning the [Ca++] to a lower level. When the cells were actively growing, PI fluorescence at the tip was intense and the
effect of calcium large. Cells which were growth-inhibited by increased mannitol in the medium showed a continuing increase in PI signal
that was also very calcium sensitive. In contrast, the cell walls of plasmolyzed pollen tubes stained less intensely at the tip. The positively
charged tertiary nitrogen of PI may be competing with calcium for binding to pectin. At the tip, where pectin polymers are rapidly
demethylated, PI access to carboxyl groups of newly-deposited homogalacturan may be greater before the formation of calcium bridges. PI
may be an excellent marker for the process of wall formation as well as for the final amount of wall pectin in pollen tubes.
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(a) School of Natural Science, Hampshire College (b) Department of Biology, Long Island University (c) Department of Biology and the Plant
Biology Graduate Program, University of Massachusetts
P17013 Identification and Characterization of Maize Cell Wall Biosynthetic Genes containing Mu-inserts
O'Brien, Brent-presenter [email protected](a)
Avigne, Wayne T (a)
settles, A Mark (a)
Hannah, Larkin C (a)
McCarty, Donald R
(a)
Koch, Karen E (a)
Vermerris, Wilfred (a)
The maize cell wall is a composite of numerous carbohydrate-based compounds. Understanding genes that control how these components
are synthesized and integrated will be invaluable to our efforts to better utilize maize for grain, fiber, and renewable energy. Here, we
characterize knockout mutations in three cellulose synthases (CESA7, CESA8, and a previously undescribed paralog of CESA7) and a
cellulose synthase-like gene (CSL-E ). The cellulose synthases being investigated have been shown to be expressed at relatively high levels
in tissues undergoing the transition from primary to secondary cell wall biosynthesis (Appenzeller et al., 2004). The CSL mutant, csl-E, may
be deficient in glucan synthase activity, however the specific function of this gene has not been described. These mutants were generated
in the transposon-mutagenic Uniform Mu population, thus providing a means for new mutations to be identified, localized to a specific gene,
and studied in a uniform, inbred background. The CESA and CSL mutants are being tested for phenotypic associations with knockout genes
under field conditions. Developmental and morphological characterization is continuing at the whole-plant and cellular levels. In addition,
tissue specific gene expression analyses are being conducted for each of these genes throughout development. We have also identified and
tested several other mutants harboring a Mu-insertion in potential cell-wall biosynthetic genes, however these have not been associated
with visible phenotypes thus far. These genes include; a polygalacturonase, a β-galactosidase, a glucose-4-6-dehydratase, and an
arabinogalactan protein.
(a) University of Florida
Session P18 – Cytoskeleton Structure & Dynamics
P18001 Myosin XI is required for Golgi assembly and tip growth
Vidali, Luis (a)
Kerdavid, Erin (a)
Gisbergen, Peter van (a)
Fay, Scotty (a)
Bezanilla, Magdalena-presenter
[email protected](a)
Physcomitrella patens has two myosin XI genes, both of which are expressed in protonemal tissue. To investigate the role of myosin XI
during protonemal cell growth, we used RNAi to silence both myosin XI isoforms simultaneously by generating an inverted repeat RNAi
construct that incorporates ~300 bp from each gene. Transformation of the myosinXI-RNAi construct into moss protoplasts and subsequent
plant regeneration results in dwarf plants composed of small rounded cells, which phenocopy plants that have been treated with the actin
depolymerizing drug, latrunculin B. The myosinXI-RNAi plants only survive for about one week after transformation. Thus, we have shown
that myosin XI is essential for plant viability and tip growth. To begin to address how myosin XI functions in tip growth, we analyzed the
localization of the Golgi in myosin XI silenced plants by transforming the myosinXI-RNAi construct into a stable moss line that expresses YFP
targeted to the Golgi. In these plants, we observed diminished YFP fluorescence. Confocal imaging shows that this reduction is due to a
marked decrease in size and number of Golgi bodies, suggesting that myosin XI may play a role in maintenance and assembly of the Golgi
apparatus. Additionally proper localization of the Golgi is required for tip growth in moss as shown by imaging of Golgi in growing
protonemal cells. The Golgi is localized to the apex of the cell and upon treatment with latrunculin B the Golgi is immediately dispersed
away from the tip and growth stops concurrently. Thus, we propose that myosin XI contributes to tip growth by localization and
maintenance of the Golgi near the apex of the cell.
(a) University of Massachusetts - Amherst
P18002 Class II formins are essential for actin organization and tip growth
Vidali, Luis-presenter [email protected](a)
Gisbergen, Peter van (a)
Augustine, Robert C (a)
Bezanilla, Magdalena (a)
Formins are nucleators of actin polymerization, shown to be essential for actin-mediated processes in animals and fungi. Plants have two
distinct families of formins. We have analyzed the function of formins in the moss Physcomitrella patens using a loss of function analysis.
Moss has eight formin genes, six belong to class I and two belong to class II. We generated RNAi constructs that silence all six class I, both
class II, and all eight formin genes. RNAi of all class I formins produces small plants. However, the plants are normal in morphology. In
contrast, RNAi of the two members of class II formins leads to a dramatic loss of tip growth. Plants are dwarfed and composed of a cluster
of spherical cells. These data suggest that while class I formins may be required for optimal growth, class II formins are required for
establishing polarity, demonstrating for the first time the essential role of class II formins in plant cell tip growth. Additionally, we show that
the two class II formin genes are functionally redundant, since we are able to rescue tip growth by expressing a single class II formin gene
and specific silencing of either gene alone has no detectable phenotype. Loss of all eight formin genes is lethal; few plants are recovered
and many show signs of cell death. Moss protonemal cells contain axially aligned F-actin and a striking structure composed of cortically
associated F-actin bundles that form a fringe near the tip of the cell. Loss of class I formins does not affect this organization. However, loss
of class II formins dramatically alters the F-actin organization, resulting in loss of the fringe. We propose that the critical role of class II
formins in polarization is to properly assemble and maintain the subapical cortical F-actin fringe.
(a) University of Massachusetts - Amherst
P18003 Protein Kinase-Protein Phosphatase Interplay Modulates Microtubule Organization in Arabidopsis Cells
Yemets, Alla I. (a)
Sheremet, Yarina O. (a)
Visenberg, Kris (b)
Van Orden , Jürgen (b)
Verbelen, Jean-Pierre (b)
Blume,
Yaroslav B.-presenter [email protected](a)
To elucidate the functional role of tubulin phosphorylation, a reversible posttranslational modification of serine/threonine (Ser/Thr) and
tyrosine (Tyr) residues, for plant microtubule (MTs) reorganization the effects of different inhibitors of Ser/Thr (olomoucine, staurosporine,
H7 and W7) protein kinases (PKs) and tyrosine kinases (TKs) (genistein, herbimycin A and tyrphostin AG18) as well as inhibitors of Ser/Thr
(okadaic acid) and Tyr (sodium orthovanadate) protein phosphatases (PPs) were examined on Arabidopsis thaliana root cells expressing
GFP-MBD. Seedling treatment with Ser/Thr PKs inhibitors reduced elongation of primary roots and altered their morphology. Treatment with
olomoucine, H7 and W7 resulted in re-orientation of cortical MTs from transverse to longitudinal in epidermal and cortex cells of root
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PB 2008
elongation and differentiation zones. However, treatment with okadaic acid stabilized, re-oriented or even disorganized MTs in epidermal
and cortex cells of same root zones. Also, okadaic acid affected root hair morphology; namely, root hairs swelling and branching, as a result
of abnormal MTs orientation. Inhibitors of Tyr-PKs disoriented and disrupted MTs in epidermis and cortex cells of elongation and
differentiation root zones, led to alteration of root hairs growth and development. Changes in MT orientation from transverse to longitudinal
in epidermal and cortex cells of elongation and differentiation zones, and intensive root hair growth were observed after treatment with
orthovanadate. Significant effects of different inhibitors of PKs and PPs on MT organization leading to altered root growth and development
can be interpreted in the terms of tubulin phosphorylation/dephosphorylation involvement into these processes.
(a) Institute of Cell Biology and Genetic Engineering (b) University of Antwerpen
P18004 Nitric Oxide Signaling via Microtubules in Arabidopsis thaliana Cells
Yemets, Alla I.-presenter [email protected](a)
Krasylenko , Yuliya A. (a)
Sheremet,, Yarina O. (a)
Blume, Yaroslav B. (a)
Most of diverse functions of nitric oxide (NO), a diffusible second messenger, attributed in plants (from cell growth and developmental
processes to pathogen defense, stress tolerance and programmed cell death) can be based on signaling via microtubules (MTs). The effects
of NO-donor sodium nitroprusside (SNP) on MT organization in Arabidopsis thaliana root cells as a possible target for α-tubulin
nitrotyrosination were elucidated. Seedlings of A. thaliana expressing GFP-MBD were treated with SNP (10-500 mkM) during 4-48 h. Primary
root growth was stimulated during first 24 h after SNP treatment, while its treatment during 48-72 h decreased significantly root length.
These effects of SNP corresponded with its influence on root morphology. After 24 h of SNP (250 and 500 mkM) treatment the zone of root
hair formation (maturation zone) was considerably enlarged. SNP treatment during 48 h led to significant reduction of cell growth in
elongation zone, whereas significant stimulation of cellular differentiation resulted in new root hair formation. Simultaneously, significant
effects of SNP on MT organization in different root cells were observed. Elongation zone epidermal cells were most sensitive to SNP, where
MT orientation was considerable disturbed. 24 h treatment with 250 mkM SNP changed MT orientation from transverse to oblique or even
longitudinal in elongation zone epidermal cells. Ttreatment with SNP (500 mkM) during 4 h led to MT randomization, whereas 24 h
treatment resulted in change of MT orientation from transverse to longitudinal in these cells. Because SNP disrupted cortical MT orientation
in a time- and dose-dependent manner we suppose that SNP causes new root hair formation through cortical MT reorganization based on
tubulin nitrotyrosination.
(a) Institute of Cell Biology and Genetic Engineering
P18005 Comparative study of the actin-associated functions of the plant LIM family members
Papuga, Jessica-presenter [email protected](a)
Hoffmann, Celine (a)
Moreau, Flora (a)
Monika, Dieterle
(a)
Clement , Thomas (a)
Stephane, Tholl (a)
Andre, Steinmetz (a)
Actin binding proteins (ABPs) are major regulators of the actin cytoskeleton organization and dynamics that possess the ability to interact
directly with actin molecules. The ABP subset of cross-linkers triggers the formation of two important high-order actin structures: networks
(orthogonal arrays of actin filaments) and bundles (parallel arrays of closely packed actin filaments). In plant cells bundles are required for
organelle and vesicle movement as well as for trans-cytoplasmic strand stabilization. In addition, they may also play important roles during
cell elongation and morphogenesis. To date, three main actin bundling protein families have been identified in plants: the fimbrins, villins
and formins. Our recent data show that LIM proteins form an additional bundling protein family. Indeed, we found that the tobacco
NtWLIM1 protein has the capacity to bind directly to actin filaments, to stabilize them and induce the formation of actin bundles both in
vitro and in plant cells (Thomas et al., 2006 Plant Cell 18: 2194-2206; Thomas et al., 2007 JBC 282: 33599-33608). Importantly, plant
genomes code for several LIM proteins, raising the question as to whether all the members of the family display the same actin regulatory
functions. To address this issue we are conducting a comparative study that includes the six Arabidopsis LIM proteins. The actin-binding and
-bundling activities of recombinant LIM proteins have been assessed and compared using high- and low-speed co-sedimentation assays
respectively. Confocal microscopy analyses of transgenic Arabidopsis lines over-expressing GFP-fused LIM proteins are also presented.
Together these data provide a better comprehension of the biological roles of the plant LIM protein family.
(a) CRP-Sante
Session P19 - Organelle Biology
P19001 Chloroplast localization of methylerythritol 4-phosphate pathway enzymes and regulation of mitochondrial genes
in ispD and ispE albino mutants in Arabidopsis
Hsieh, Ming-Hsiun-presenter [email protected](a)
Chang, Chiung-Yun (a)
Hsu, Shi-Jui (a)
Chen, Ju-Jiun (a)
Plant isoprenoids are derived from two independent pathways, the cytosolic mevalonate pathway and the plastid methylerythritol 4phosphate (MEP) pathway. We used green fluorescent fusion protein assays to demonstrate that the Arabidopsis MEP pathway enzymes are
localized to the chloroplast. We have also characterized three Arabidopsis albino mutants, ispD-1, ispD-2 and ispE-1, which have T-DNA
insertions in the IspD and IspE genes of the MEP pathway. Levels of photosynthetic pigments are almost undetectable in these albino
mutants. Instead of thylakoids, the ispD and ispE mutant chloroplasts are filled with large vesicles. Impairments in chloroplast development
and functions may signal changes in the expression of nuclear, chloroplast and mitochondrial genes. We used northern blot analysis to
examine the expression of photosynthetic and respiratory genes in the ispD and ispE albino mutants. Steady-state mRNA levels of nucleusand chloroplast-encoded photosynthetic genes are significantly decreased in the albino mutants. In contrast, transcript levels of nuclear and
mitochondrial genes encoding subunits of the mitochondrial electron transport chain are increased or not affected in these mutants.
Genomic Southern blot analysis revealed that the DNA amounts of mitochondrial genes are not enhanced in the ispD and ispE albino
mutants. These results support the notion that the functional state of chloroplasts may affect the expression of nuclear and mitochondrial
genes. The up-regulation of mitochondrial genes in the albino mutants is not caused by changes of mitochondrial DNA copy number in
Arabidopsis.
(a) Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
P19002 Suppressors of the var2 variegation mutant of Arabidopsis provide access to regulatory networks that govern
chloroplast biogenesis
177
Rodermel, Steven-presenter [email protected](a)
Yu, Fei (a)
Liu, Xiayan (a)
Xu, Yang (a)
Undifferentiated proplastids in the apical meristem are converted into photosynthetically-competent chloroplasts early in leaf development.
We are using Arabidopsis var2 variegation mutants as a tool to gain entrance into the mechanisms that regulate chloroplast development.
These mutants contain green- and white-sectored leaves due to the action of a nuclear recessive gene; all the tissues of the mutant have a
uniform (mutant) genetic constitution, but only the white sectors have a mutant phenotype. VAR2 codes for an FtsH metalloprotease that is
anchored in the thylakoid membrane as part of a larger AtFtsH complex. It mediates turnover of the D1 protein of PSII and thus plays a
central role in photoprotection. VAR2 has also been implicated in a number of other chloroplast processes, but little is understood about the
molecular details. To better understand the function of VAR2 and the mechanism of var2 variegation, we have carried out second-site
suppressor screens of var2 using EMS and activation tagging mutagenesis. Over 100 loss-of-function and gain-of-function suppressor lines
with non-variegated phenotypes have been isolated. The suppressor genes in five of these lines have been cloned and characterized. These
genes code for known components of the chloroplast, as well as several novel proteins with previously unknown functions. The latter
include a protein that associates with PSI and is essential for growth and development. To describe the interactions between VAR2 and its
suppressors we have constructed a Genetic Interactions Network. This network provides insight into mechanisms of var2 variegation and
chloroplast biogenesis. In our presentation we will describe the cloning results and our genetic network.
(a) Iowa State University
P19003 Defining the plant peroxisome and modeling its function
smith, steven M.-presenter [email protected](a,b)
bussell, John D. (a,b)
Zhou, Wenxu (a,b)
Millar, Harvey (a,c)
Small,
Ian D. (a,c)
Castleden, Ian (a,c)
Che, Ping (a,b)
Eubel, Holger (a)
Meyer, Etienne H. (a)
O'Toole, Nick
(a,c)
Pracharoenwattana, Itsara (a,b)
Taylor, Nicolas (a)
Wiszniewski, Andrew (a,b)
http://www.plantenergy.uwa.edu.au
Predictions of peroxisomal proteins based on putative PTS sequences have identified between two and three hundred proteins (Reumann et
al, Plant Physiol. 136:2587-608, 2004). Proteome analysis of isolated Arabidopsis leaf peroxisomes has identified 78 proteins (Reumann et
al, Plant Cell 19:3170-93, 2007). We have purified organelles from Arabidopsis cell cultures and defined a set of over 100 peroxisomal
proteins extending the total number identified to approximately 130. Confirmation of the peroxisomal location of some of these proteins is
being established using GFP fusions. Many of these proteins are recognized peroxisomal proteins with established functions, while others
are of unknown function. To investigate protein functions and examine their possible relationships we have interrogated functional genomics
data and are systematically isolating mutants for phenotypic analysis. These studies provide us with an inventory of component parts with
which we are building a model of peroxisome function. The model is being refined and extended through continued addition of new
information and testing using reverse genetics and phenotypic analysis. The aim is to build a complete in silico model of the peroxisome
which will allow us to undertake rational design of key functions such as those involved in energy metabolism, oxidative stress and plant
development.
(a) ARC Centre of Excellence in Plant Energy Biology, University of Western Australia (b) Centre of Excellence for Plant Metabolomics,
University of Western Australia (c) Centre of Excellence in Computational Systems Biology, University of Western Australia
P19004 Characterization of Arabidopsis peroxins acting in matrix protein import
Martinez, Naxhiely-presenter [email protected](a)
Woodward, Andrew (a)
Bartel, Bonnie (a)
Peroxisomes are single membrane-bound organelles that function to compartmentalize certain metabolic reactions critical to human and
plant development. We are studying peroxisomal processes in the model plant Arabidopsis thaliana, with a focus on the import of matrix
proteins from the cytoplasm into the organelle matrix. This import depends on more than a dozen peroxin (PEX) proteins, with PEX5 and
PEX7 serving as receptors that shuttle proteins bearing a peroxisome targeting sequence (PTS) into the organelle. PEX5 is the PTS1
receptor, PEX7 is the PTS2 receptor, and in both plants and mammals, PEX7 depends upon PEX5 binding to deliver PTS2 cargo into the
peroxisome. We are elucidating the functions of Arabidopsis PEX7 in peroxisomal matrix protein import. We are characterizing pex7 mutants
isolated through forward and reverse genetic screens in physiological and biochemical assays. To determine whether the pex7 mutations
disrupt PEX7-cargo binding, PEX7-PEX5 interactions, or PEX7 stability, we have examined localization of various peroxisomally targeted GFP
derivatives and endogenous peroxisomal enzymes in the pex7 mutants. We are characterizing the interactions between mutant and wildtype PEX7 and PEX5 derivatives using the yeast two-hybrid assay, overexpression studies, and double mutant analyses. In humans,
deficiencies in PEX7 and other peroxins underlie the peroxisomal biogenesis disorders, which are frequently lethal in early infancy.
Successful completion of these experiments will advance our understanding of peroxisome biogenesis and metabolism in a genetically
distinct model system, which will allow the continued refinement of our understanding of these essential organelles.
(a) Rice University
P19005 Physiological cost of illegitimate mitochondrial DNA recombination in higher plants
Arrieta-Montiel, Maria-presenter [email protected](a)
Sandhu, Ajay (a)
Shedge, Vikas (a)
Xu, Ying-Zhi (a)
Mohammed,
Saleem (a)
Christensen, Alan (a)
Mackenzie, Sally (a)
Plant growth and development require coordinated expression of genes located in the nucleus, chloroplast and mitochondria. The
maintenance of mitochondrial genome stability relies on the nuclear genome, which encodes majority of mitochondrial proteins. In plants, 3
nuclear genes, Msh1, RecA3 and Osb1 have been shown to participate in recombination surveillance and the suppression of illegitimate
recombination in mitochondria. Disruption of these loci in Arabidopsis results in reproducible rearrangement of the mitochondrial genome.
Transgenic suppression of Msh1 by RNAi in crop plants (tobacco, tomato, soybean and pearl millet) produces mitochondrial genome
alteration and the associated phenotype of cytoplasmic male sterility. Interestingly, leaf variegation and stunted plant growth phenotypes
were also observed consistently in the 4 plant species. These phenotypes showed maternal inheritance, and a comprehensive analysis of
the derived mitochondrial genomes using 23 mitochondrial gene probes revealed distinct mitochondrial genome alterations associated with
each phenotype in tomato. Our observations suggest that mitochondrial genome rearrangement in response to depletion of Msh1 is
followed by a process of cytoplasmic sorting to produce distinct cytotypes. Mitochondrial genome alterations were also accompanied by
dramatic changes in mitochondrial gene expression. To date, opportunities to investigate mitochondrial genetics in higher plants, and to
understand the role of mitochondrial gene expression in plant growth and development, have been limited and artificial. Here we describe a
natural consequence of nuclear gene modulation to produce a host of mitochondrial variants providing insight into the mitochondrial
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PB 2008
intersection of several important cellular pathways.
(a) University of Nebraska - Lincoln
P19006 Bioinformatic and functional screens for new Arabidopsis peroxins
Poggio, Elizabeth A-presenter [email protected](a)
Bartel, Bonnie (a)
Peroxisomes carry out diverse functions in plants, including fatty acid β-oxidation, hydrogen peroxide decomposition, hormone metabolism,
and certain steps in photorespiration. These single membrane bound organelles contain no DNA, and so all peroxisomal matrix proteins
must be imported post-translationally. The proteins responsible for matrix protein import are known as peroxins. Peroxins in yeast have
been identified through genetic screens and human homologs for many of these are the genes defective in peroxisome biogenesis
disorders. Although many proteins have been identified that play a role in matrix protein import, the process is still incompletely understood,
and not all proteins involved in matrix protein import in yeast and mammals have identified Arabidopsis homologs. For example, the peroxin
that tethers PEX6 to the peroxisome membrane, Pex15p in yeast and PEX26 in humans, is not apparent in the Arabidopsis genome. We
hypothesize that components of the receptor recycling machinery that are conserved between yeast and mammals also have homologs in
Arabidopsis. We are combining bioinformatic and functional yeast expression approaches to identify PEX15/26 candidates in Arabidopsis,
and will characterize the roles of these candidates in peroxisomal function.
(a) Rice University
P19007 Diverse impacts of PPR knockout mutations on Arabidopsis embryo morphology, cell organization, and plastid
development.
Vernon, Daniel M.-presenter [email protected](a,b)
Davis, Nick A (a)
Forsthoefel, Nancy R (a)
Pentatricopeptide Repeat proteins (PPRs) constitute one of the largest superfamilies in plants, with more than 440 identified in Arabidopsis.
While some PPRs are known to take part in post-transcriptional steps of mitochondrial and plastid gene expression, little is known about the
broader biological contexts of PPR gene function. We previously identified a subset of Arabidopsis PPR genes, EMB-PPRs, that are essential
for normal embryogenesis and morphological development. To better understand PPR functions in early development, we investigated the
impacts of knockout mutations in two EMB-PPR genes, here designated as EMB-PPR2 and EMB-PPR3. The embryonic functions of these
genes were confirmed with second alleles, and RT-PCR confirmed that both mutations were full knockouts. Mutant embryos had dramatic
morphological defects, including stunted cotyledons and enlarged shoot apices. Histological analysis revealed abnormal cell shape and
organization in mutant cotyledons; defects were more severe in emb-ppr2. TEM of cotyledons indicated that proplastid development and
thylakoid formation were arrested to a different degree in each mutant, establishing plastid function for both EMB-PPR2 and 3. Reduced
expression of photosynthesis-related genes was demonstrated by RT-PCR. Taken together, these results reveal that EMB-PPR2 and EMBPPR3 are critical at different stages of embryonic plastid development and that these genes have distinct impacts on embryo morphology, as
well as cotyledon cell and tissue organization. These mutants underscore the importance of plastids in embryogenesis and provide a system
for further investigation of plastid maturation and PPR gene functions in early plant development. Supported by NSF award 0616166
(a) Biology Department, Whitman College (b) Program in Biochemistry, Biophysics & Molecular Biology, Whitman College
P19008 Mechanism of conversion from heterotrophy to autotrophy in Euglena
Osafune, Tetsuaki -presenter [email protected](a)
Lyman, Harvard (b)
Euglena grown to stationary phase in the dark without aeration accumulated lipids. When these high lipid cells are transferred to an
inorganic medium and aerated, lipids were rapidly metabolized and the respiratory rate declined concomitant with the decline in cellular lipid
content. Prolamellar bodies, propyrenoids and prothylakoids developed within the proplastid of dark aerated cells and the cells developed an
increased capacity for chlorophyll synthesis manifested upon subsequent exposure to light. Lipid content did not decline in cells exposed to
nitrogen and chlorophyll synthesis ability did not increase. The addition of an organic carbon source to cells at the start of aeration did not
prevent lipid degradation. Organic carbon source addition and inhibitors of RNA and protein synthesis did however inhibit the development
of an increased capacity for chlorophyll synthesis. These results suggest that oxygen triggers light independent proplastid development with
the oxidative metabolism of lipids providing the carbon and energy for the synthesis of nucleic acids and proteins required for proplastid
development in the dark.
(a) Dept Life Science, Nittai University, Yokohama, 227-0033 Japan (b) Department of Biochemistry & Cell Biology, Stony Brook University,
Stony Brook, NY 11794-5215
P19009 Mitochondrial DNA recombination in Arabidopsis thaliana
Nielsen, Brent L-presenter [email protected](a)
Cupp, John D (a)
Hunt, Travis (a)
Liu, Bin (a)
Plant mitochondrial genomes are large with complex structure, and analysis suggests the DNA (mtDNA) consists of linear and multiply
branched molecules, and may replicate by a recombination-dependent mechanism. We have previously identified a nuclear gene in
Arabidopsis thaliana that encodes a mitochondrial-targeted homologue of bacterial RecA. Our hypothesis is that this RecA protein may be
involved in replication and/or DNA repair. To test this we have obtained T-DNA insertion and single base mutant (TILLING) seed lines for
the mtrecA gene. Homozygous insertion or mutation lines show reduced growth rates and premature flowering. Growth is further affected
in the mutant lines upon exposure to the DNA damaging chemical methylmethane sulfonate (MMS). Quantitative real-time PCR reveals a
reduction in mtDNA levels in the mutant lines. Analysis of plants by transmission electron microscopy reveals altered mitochondrial
morphology in the mutants. Current studies are being conducted to analyze expression levels for mtrecA using reverse-transcriptase PCR
and western blots with antibodies against unique regions of the RecA protein in wild-type and mutant plants, and after exposure to MMS.
We have also identified a mitochondrial-targeted DNA primase/helicase gene in Arabidopsis homologous to the phage T7 Twinkle protein,
which in other organisms is involved in proper maintenance of mtDNA. Mutations in this gene have been obtained and the lines are being
examined as for mtRecA. Some mutant lines show severe growth abnormalities. Our results suggest that these proteins are necessary for
proper plant growth and response to DNA damage. This research is supported by a grant from the NIH and by the BYU Mentoring
Environment Grants program.
(a) Brigham Young University
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P19010 Photo-oxidative stress and chloroplast DNA mutation
Sears, Barbara B-presenter [email protected](a)
Nguyen, Ngoc (a)
Enell, Matthew (a)
Blaine, Allison (a)
Dawson-Baglien, Ethan
(a)
Mayle, Ryan (a)
Using Chlamydomonas reinhardtii as an experimental organism, a genetic assay has been developed to detect damage to chloroplast DNA.
Point mutations that result in spectinomycin resistance are located at predicted sites on the cpDNA, and can be categorized as transversions
or transitions by DNA sequencing. Wild-type cells grown under continuous, moderately-high light (400 uE) experience a higher mutation
rate than do cells grown under low light conditions. The former also produce more transversion mutations, which typify damage caused by
reactive oxygen. To address the theory that the frequency and types of cpDNA mutation will reflect levels of photo-oxidative stress, we have
tested several strains of Chlamydomonas that are altered in their light-sensitivity for a correspondence in the susceptibility of their cpDNA to
mutation. The Niyogi npq1 lor1 strain, which is deficient in specific antioxidants (zeaxanthin and lutein) and in non-photochemical
quenching, was found to have an elevated mutation rate. Contrary to our expectations, the very high light resistant (VHLR) strains of Britta
Foerster showed an exceptionally high frequency of cpDNA mutation. In contrast, no change in rates of cpDNA mutation were observed for
cells treated with the superoxide-producing chemical, methyl viologen, nor the singlet oxygen-generating Rose Bengal at sublethal
concentrations. These observations indicate that the cpDNA and the photosynthetic apparatus are differentially susceptible to damage from
reactive oxygen.
(a) Michigan State University
P19011 Comparative analysis of post-transcriptional and translational regulation of mitochondrial atp6-orf79 by fertility
restorer genes in LD-type and BT-type cytoplasmic male sterility of rice
Itabashi, Etsuko-presenter [email protected](a)
Toriyama, Kinya (a)
Cytoplasmic male sterility (CMS) is a maternally inherited trait that results in the inability to produce fertile pollen and is often associated
with an usual orf found in mitochondrial genomes. LD-CMS of rice possesses the cytoplasm of Lead Rice and its fertility is recovered by
nuclear restorer gene, either Rf1 or Rf2. BT-CMS has the cytoplasm of Chinsurah Boro II and its fertility is fully recovered by Rf1 and
partially recovered by Rf2. It has been reported that post-transcriptional processing of BT-CMS-associated genes B-atp6-orf79 and
suppression of accumulation of ORF79 occurred in the presence of Rf1. In this study, we compared the structure and post-transcriptional
and translational regulation of the atp6 genes between LD-CMS and BT-CMS in relation to the effect of Rf1 or Rf2. We found that LD-type
cytoplasm contained novel genes highly homologous to B-atp6-orf79, which we designated as L-atp6-L-orf79. Northern blot analysis and
Western blot analysis showed that the function of Rf2 is different from that of Rf1 and L-ORF79 is not the cause of LD-CMS.
(a) Tohoku University
P19012 Induction of cytoplasmic male sterility using Msh1-RNAi suppression in monocots
Feng, Xuehui-presenter [email protected](a)
Sato , Shirley (a)
Dweikat, Ismail (b)
Sandhu, Ajay (a)
Clemente, Tom
(a)
Mackenzie, Sally (a)
Msh1 gene is involved in maintaining mitochondrial genome stability in higher plants. RNAi-mediated knockdown of Msh1 expression results
in mitochondrial genome rearrangements and induction of various plant phenotypes in dicots. To test the possibility of inducing novel
mitochondrial genotypes in monocots, Msh1-RNAi suppression constructs were stably introduced into fertile lines of pearl millet (Pennisetum
americanum) and sorghum (Sorghum bicolor). Rearranged mitochondrial genome configurations and evidence of substoichiometric shifting
were observed in both species. Some of the emerging mitochondrial DNA patterns resemble those already present in natural CMS lines.
Msh1-RNAi suppression blocked pollen development and caused male sterility in both species. The induced trait was heritable and nonreversible upon segregation of the transgene in millet (not tested yet in sorghum). These experiments provide further evidence that
modulation of Msh1 can serve as an approach to induce novel CMS forms in crops. In addition, other phenotypes such as stunted growth,
variegated leaves and indeterminate vegetative growth were observed in some progeny. This mitochondrial mutation system is valuable for
studying mitochondrial-nuclear interactions and their regulation in plant growth and development.
(a) Center for Plant Science Innovation, UNL (b) Agronomy & Horticulture, UNL
P19013 Novel signaling pathways that coordinate chloroplast protein import and the expression of nuclear-encoded
chloroplast proteins
Kakizaki, Tomohiro-presenter [email protected](a)
Matsumura, Hideo (b)
Nakayama, Katsuhiro (c)
Terauchi, Ryohei (b)
Inaba,
Takehito (c)
http://www.iwate-u.ac.jp/coe/inabag/
The cooperative gene expression in the two organelles, the nucleus and chloroplasts, is indispensable for construction of the photosynthetic
machinery in chloroplasts of higher plants. At present the chloroplast genome encodes fewer than 100 ORFs in Arabidopsis, and most of the
genes encoded by the bacterial ancestor have been transferred to the host nuclear genome. Therefore, to maintain the function of
chloroplasts, it is important f to control the expression of nuclear-encoded chloroplast proteins strictly in response to the metabolic state of
chloroplasts. However the molecular mechanisms underlying this inter-organelle signaling remains to be char