Download Photosynthesis, Physiology and Growth of Orchids

Photosynthetic Pathways in
Higher Plants
Photosynthesis, Physiology
and Growth of Orchids
C3: temperate, without CO2 concentrating mechanism
C4: tropical origin, with CO2 concentrating mechanism
國立嘉義大學
古森本
CAM: arid, with CO2 concentrating mechanism
Maurice S. B. Ku
National Chiayi University
Evolution and Diversity of Photosynthetic Mechanism
among Higher Plants
C4 (~3%)
(terrestrial, obligate)
?
Low CO2 , warm climate
C3
Evolution of Cyanobacterial, Algal and Terrestrial Plant CO2
Concentrating Mechanisms (CCMs)
Angiosperms
Embryophyta
Modified from Badger et al.
2002. FPB 29:61
C3-C4
C3
Decreasing CO2
(aquatic, ancestral)
O2 %
Chlorophyceae
Rhodophyta
20
Eukaryotic algae
Low CO2 , warm and dry climate
CAM
40
30
(aquatic or terrestrial, obligate)
Low CO2, aquatic environments
Multicellular photosynthesis
Land plants
Unicellular
photosynthesis
(~90%)
Gymnosperms
Pteridophytes
Bryophyta
RCO2
(past/present)
10 CARB III
(~5%)
(terrestrial, facultative or obligate)
model
O2 evolving photosynthesis
Cyanobacteria
0
Start of cyanobacterial Start of
and algal CCMs ?
terrestrial CCMs?
C3-CAM (aquatic, facultative)
HCO3-
pump (aquatic, facultative)
ARCHAEAN
3500
3000
PROTEROZOIC
2500 2000 1500 1000 600 500
Millions of Years Before Present
PHANEROZOIC
400
300 200
100
0
1
Opuntia
CAM Plants
Paphiopedilum
Rice: C3 plant
Temperate or subtropical origin
One photosynthetic cell
succulent,
Photosynthesis is not saturated by atm. CO2
levels, with high photorespiration
thick leaf,
central H2O
Maize: C4 plant
Tropical origin
storage cells,
Two photosynthetic cells (Kranz anatomy)
one photosynthetic mesophyll cell type,
Photosynthesis is saturated at atm. CO2
levels, with low photorespiration
fix CO2 in the night, few stomates
Leaf anatomy – C3, C4
C4 - Kranz anatomy
Mesophyll cells
Bundle sheath cells
Maize: Kranz
MC
C3 -
BSC
Mesophyll cells
(Surridge, 2002)
Rice: non-Kranz
MC
Undifferentiated
BSC
2
C4 plants are more efficient in utilizing low atm CO2
C4 plants have a higher photosynthetic capacity, especially under high
light and warm temperature conditions
Atm. CO2
Sage (2000)
Ku et al. (1999)
C4 plants have a higher nitrogen use efficiency
Maize
Higher photosynthetic rates lead to higher growth rates
Evans &
Caemmerer
(2000)
Sharkey et al. (2000)
Sorghum
Maize
Rice, Wheat
Bean
Castor bean
Sunflower
3
C4 and CAM plants have a higher water use
efficiency than C3
C3: 550-850
g H2O/g DM
C4: 250-350
g H2O/g DM
C3 pathway:
Photorespiration and CO2/O2 ratio
O2 - Oxygenase
Rubisco
CO2 - Carboxylase
Photorespiration – CO2 loss
CAM: 150-250 g H2O/g DM
C4: high photosynthetic rate, lower stomatal frequency
higher stomatal resistance to CO2 diffusion.
CAM: thick leaf, lowest stomatal frequency, open in the night when
temperature is low, fix CO2 in the night
The C4 Pathway in NADPNADP-ME Subtype
Borszczowia aralocaspica,
a C4 Species Without Kranz Anatomy (Freitag and Stichler 2000)
(Buchanan et al. 2000)
MC
PEPC
NADP-MDH
CA
CO2
CO2
PPDK
BSC
NADP-ME
CO2
Unstacked (PSI)
Unstacked (PSI)
Stacked (PSII)
C4: Carboxylation phase
Regeneration phase
C4: Decarboxylation phase
C3: Refixation of CO2
This succulent dicot species from Central
Asia has dimorphic chloroplasts located in
different positions within one single
chlorencyhma cell. Its mechanism for C4
photosynthesis remains to be elucidated.
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Distal region:
PEP carboxylase
CAM pathway
Pyruvate, Pi dikinase
Intracellular
compartmentation of the
C4 pathway in
Borszczowia
(Vozesenskaya, et al., 2001)
Rubisco
Proximal region:
C4-acid decarboxylation enzyme
Rubisco
The Four Phases in a Typical CAM
(Taiz and Zeigler, 2003)
Criteria to identify C3, C4, CAM Plants
Leaf anatomy or morphology
Night - PEPC
Day - Rubisco
Enzyme activity
CO2 gas exchange pattern
CO2 compensation point
14CO2
labeling
Discrimination again 13CO2 during
photosynthesis
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Good criteria for identification of
CAM Plants
CO2 Composition in Atmorsphere
98.892%
Succulence
1.108%
Night CO2 fixation
Night accumulation in acidity (malate)
Day decrease in acidity (malate)
Discrimination against
13CO2
Major Factors Related to
13CO2
Diffusion of CO2 in air (C3, C4, CAM) :
+ 4 per mil (discrimination)
Equailibrium of CO2 to
CAM) :
- 8 per mil (enrichment)
HCO3- (C4,
PEPC (C4, CAM) :
Rubisco (C3) :
+ 2 per mil
+ 34 per mil
Trace
1.116%
13CO2
12CO2
13CO2
14CO2
in PBD stone (standard)
Heavier isotopes rich in low elevation
Expected values for C3, C4 and CAM
C3: (+4) + (+34) + (-7) = +31
C4: (+4) + (+2) + (-7) + (+8) = +7
CAM: between C3 and C4 values
depending on the degree of CAM (C4)
Why Rubisco is not a factor for C4 ?
6
Identification of C3, C4, CAM plants by 13C content
Anatomical, Physiological and Biochemical
Characteristics – C3, C4, CAM
Anatomical, Physiological and Biochemical
Characteristics – C3, C4, CAM
CAM in Aranda
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CAM activity in Encyclia tampensis
CAM in Arachnis
Aerial roots, not terrestrial
roots, perform CAM.
Very young leaf is not
capable of performing
CAM.
CAM in the roots of shootless
orchid Chilochista usneoides
CAM activity in Encyclia tampensis
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The genus Oncidium
Oncidium goldiana may be a weak CAM
– C3, weak and strong CAM
If leaf thickness >2.5 mm: CAM (weak and strong)
Strong CAM are mostly epiphates in warm regions
Mutiple origins of CAM in the genus
O. carthagenense – strong CAM ( no C3)
O. ampliatum – CAM (C3/CAM)
O. sphacelatum – weak CAM (more C3)
O. ornithorrhyncham – C3
(Cushman and Winter, 2008)
Effect of Drought on CAM in
Phalaenopsis
Effect of leaf
age on CAM in
Phalaenopsis
Mature leaves
display a higher
night fixation
(CAM).
Severe
drought
lowers its
CAM
activity.
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執行成果
Effect of contineous
light on CAM in
Phalaenopsis at
different
temperatures
It is an obligate CAM
with an optimal
o
temperature at 25 C.
Effect of Different
Day/Night
Temperatures on CAM
in Phalaenopsis
Optimum temerature
regime: 25/15-20oC.
Lower or higher
day/night temperatures
lowers CAM activity.
Low temperature favor
C3.
Effect of Developmental Stage
on CAM in Phalaenopsis
Initial Photosynthetic Products
in Bromeheadia finlaysonia and Arundina graminifolia
Flowering
promotes
CAM
activity.
10
Changes in Day/night Titratable
Acidity in Some Orchids
Thickleaved
orchids
tend to be
CAM and
vice versa.
Carbon Fixation in
Non-foliar Organs
of Some Orchids
Leaf thickness and
13C
content on some orchids
A good
correlation
exists
between leaf
thickness
(succulence)
and CAM in
orchids.
Carbon Fixation in Non-foliar Organs
of Some Orchids
In orchids, leaf,
stem, flower stalk,
pseudobulb and
aerial root are all
capable of fixing
atmospheric CO2 by
the same
photosynthetic mode.
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Effect of day
length on CAM
activity in
Effect of light
on CAM activity
in Phalaenopsis
Phalaenopsis
amabilis
amabilis
Long day promotes C3
photosynthesis.
400-500 μmol/m2/s
(20% of full sunlight)
appears to be optimum
for photosynthesis in
Palaneopsis.
Short day promotes CAM.
12-14 h of photoperiod
appears to be optimum for
photosynthesis in
Phalaenopsis.
(李哖, 2002)
(李哖, 2002)
Photosynthetic Response of Orchids to Light
Effect of Light
Intensity on
Photosynthesis in
Palaenopsis
amabilis
Fv/Fm = e transport efficiency via PSII
Too much light cause
photoinhibition.
Phalaenopsis is
adapted to low light
conditions, presumably
due to a low
photosynthetic
capacity.
(李哖, 2002)
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Effect of CO2 enrichment on
Photosynthesis and Growth of
Orchids
Effect of virus on CAM activity in
Epidendrum elongatum
1. CO2 enrichment suppresses photorespiration, enhances photosynthesis
and promotes growth of C3 plants due to increased CO2/O2 ratio.
Water use efficient is also increased.
2. Its effect on photosynthesis and growth of C4 plants is less significant,
but WSU is also increased.
3. Therefore, C3 orchids will benefit most from CO2 enrichment and weak
CAM with C3 photosynthesis will also benefit to some extent.
Inflorescence growth and size of Oncidium goldiana were increased by
elevated CO2 (1% and 10%).
Pleione bulbocodioides – likely a C3
(薛聰賢, 1995)
Phaleanopsis
formosum
– CAM
(薛聰賢, 1995)
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Phalaenopsis - CAM
Cattleya –
CAM
(薛聰賢, 1995)
Dendrobium - CAM
(薛聰賢, 1995)
Vanda and Ascocenda - CAM
(薛聰賢, 1995)
(薛聰賢, 1995)
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Oncidium ampliatum – Likely CAM
Paphiopedium paarishii - CAM
(薛聰賢, 1995)
(薛聰賢, 1995)
Cymbidium – C3, CAM
(薛聰賢, 1995)
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