Download Fungal Biology Lecture 4b (F09)

Lecture: Growth and Development, Part
B
Biology of Fungi
BIOL 4848/6948 - Fall 2009
Sexual Development
  Sexual
reproduction involves three
fundamental processes:
Fungal Growth and
Development
  Plasmogamy
- fusion of haploid cells
- fusion of haploid nuclei
  Meiosis - reduction division
  Karyogamy
  Two
fundamental points of sexual
reproduction
  Nature
  Serves
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Nature
of sexuality
  Homothallic
vs. heterothallic
  Governed by mating type genes (compatibility)
  Arrangement of mating types
  Bipolar
compatibility - governed by a single gene
locus where one of a non-allelic pair of genes
(idiomorph) exists
  Tetrpolar compatibility - two mating type gene pairs
of multiple idiomorphs
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
of sexuality
as a survival mechanism
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Mating
type and
hormonal control
  Chytridiomycota
  Allomyces
is a
homothallic fungus
that produces
separate male and
female gametangia
that release motile
gametes
Gametangia of Allomyces. Source: www.palaeos.com/
Fungi/Lists/Glossary/GlossaryG.html
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Mating
type and hormonal control
  Chytridiomycota
(cont.)
  Females
release a pheromone, serinin, that attracts
the male gametes
  Male gametes move along a concentration gradient
  Sirenin and carotenoid color produced in male
gametangia are produced from the same precursor,
indicating mating type gene controls development of
the sex organs
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
1
Lecture: Growth and Development, Part
B
Sexual Development (cont.)
  Oomycota
Sexual Development (cont.)
  Hormonal
control in Achlya
(cont.)
  Once triggered by
antheridiol, males release
oogoniols that induce
oogonia development
  Eventually, male branches
(antherida) fuse with
oogonia
  Homothallic
or heterothallic, but
in most cases produces a colony
with both male and female sex
organs (antheridia and oogonia)
  Mating type genes control
capatibility
  Hormonal control in Achlya
  Female produces antheridiol
causing the male to increase
production of cellulase which
induces hyphal branching to
increase
BIOL 4848/6948 (v. F09)
BIOL 4848/6948 - Fall 2009
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Zygomycota
  Homothallic
or heterothallic
mating type genes that govern conversion of βcarotene to a prohormone
  Prohormone is eventually converted by mating-type
specific gene to trisporic acid
  Trisporic acid volatilizes and causes hyphae of
opposite mating type to grow towards one another
and fuse to form a zygospore
  Two
Oogonium and antheridium of Achlya. Source:
www.palaeos.com/Fungi/Lists/Glossary/GlossaryG.html
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Trisporic acid hormonal system in mating within the Zygomycota.
Sources: www.palaeos.com/Fungi/Lists/Glossary/GlossaryG.html
and Deacon, 2006
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
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Lecture: Growth and Development, Part
B
BIOL 4848/6948 - Fall 2009
Sexual Development (cont.)
  Ascomycota
  Typically
two mating types a cells and α cells
characterized system is that of Saccharomyces
  Mating is controlled by the MAT gene locus of
flanked by two other loci, MATa and MATα
  A copy of one loci is made and inserted into MAT
gene locus - this is now the mating type of the cell
  This copy can switch out after each new bud cell is
produced
  Best
Mating type loci of Saccharomyces. Source: nitro.biosci.arizona.edu/courses/
EEB320-2005/Lecture13/lecture13.html
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Ascomycota
(cont.)
  MATα
are responsible for producing:
  Peptide hormones a-factor and α-factor
  Hormone receptors
  Cell surface agglutinins
  α cells constitutively release α-factor that is
recognized by a receptor on a cells
  a cells cease growth and arrest at G1 phase of the
cell cycle, then release a-factor
Diagram of life cycle of Saccharomyces. Source: nitro.biosci.arizona.edu/
courses/EEB320-2005/Lecture13/lecture13.html
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Ascomycota
(cont.)
  Different
mating types then form outgrowths
(“schmoo” cells) with strain specific agglutinins on
their surfaces
  Agglutinins cause cells to bind to one another, which
then leads to fusion (plasmogamy), followed by
karyogamy (diploid formation)
  Subsequent induction of meiosis produces four
ascospores
“Schmoo cell”, formation of zygotes via fusion of yeast cells,
and ascospores of Schizosaccharomyces. Sources:
www.biomade.nl/AmphipathicProteins.htm, www.jbc.org,
www.visualsunlimited.com/browse/vu227/vu227486.html and,
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
3
Lecture: Growth and Development, Part
B
BIOL 4848/6948 - Fall 2009
Diagram of life cycle of Saccharomyces. Source:
www.brooklyn.cuny.edu/bc/ahp/LAD/C9/C9_tetrads.html
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Sexual Development (cont.)
  Basidiomycota
  Most
are heterothallic having one or two mating type
loci (typically termed A and B) with mulitiple
idiomorphs at each locus (e.g., A1, A2, A3, etc.)
  Successful matings occur with different idiomorphs at
each locus (e.g., A1, B1 x A2, B2)
  Different pairings of idiomorphs have allowed a
dissection of the functions of the mating-type genes
  A locus - controls pairing and synchronous
division of nuclei and initiation of clamp formation
  B locus - controls septal dissolution, fusion of
clamp branches, and increased glucanase
activity
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Mating reactions between haploid isolates of Armillaria ostoyae (with bifactorial mating system): 1.
Incompatible mating (incompatibility factors A1B1 x A1B1). 2. hemicompatible I (incomp. factors A1B1
x A1B2). 3. hemicompatible II (incomp. factors A1B1 x A2B1). 4. compatible mating, resulting in diploid
mycelium (incomp. factors A1B1 x A2B2).Source: www.padil.gov.au/viewPest.aspx?id=518
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
Species identification with the aid of mating test. 1. A. ostoyae haploid (lower) x A. borealis
haploid (intersterile – no reaction). 2. A. ostoyae diploid (lower) x A. borealis haploid (intersterile –
no reaction). 3. A. ostoyae haploid x A. ostoyae haploid (compatible – rapid diploidisation). 4. A.
ostoyae diploid (lower) x A. ostoyae haploid (intersterile – slow diploidisation of the haploid
tester) .Source: www.padil.gov.au/viewPest.aspx?id=518
BIOL 4848/6948 (v. F09)
Copyright © 2009 Chester R. Cooper, Jr.
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