Transcript No Slide Title

Processes affected by CO2
1) Pathways that consume CO2
2) pathways that release CO2
3) transpiration & stomatal number
Processes affected by [Sugar]
Energy
Biosynthesis
Storage
Structure
Osmotic regulation
Signaling molecules
Processes affected by [Sugar]
AtHXK1-Dependent Gene Expression
Photosynthesis
Photorespiration
WT vs. gin2
Fatty acid synthesis &
mobilization
Nitrogen metabolism
HXK1/GIN2
Sucrose metabolism
Starch biosynthesis
Respiration
Flavonoid synthesis
Cell wall synthesis
Defense
ROS scavenging / Detoxification
Antioxidant protection
Cytokinin signaling
Light signaling
Auxin signaling
Ca2+ signaling
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects partitioning inside cells
• 1 in 6 G3P becomes (CH2O)n
• either becomes starch in
cp (to store in cell)
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects partitioning inside cells
• 1 in 6 G3P becomes (CH2O)n
• either becomes starch in
cp (to store in cell)
• or is converted to
DHAP & exported
to cytoplasm to
make sucrose
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects partitioning inside cells
• 1 in 6 G3P becomes (CH2O)n
• either becomes starch in
cp (to store in cell)
• or is converted to
DHAP & exported
to cytoplasm to
make sucrose
•Pi/triosePO4 antiporter
only trades triosePO4 for Pi:
mechanism to regulate PS
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects starch accumulation
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects starch accumulation
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Affects starch accumulation & degradation
Processes affected by [Sugar]
Photosynthesis
• And sucrose transport
Processes affected by [Sugar]
Photosynthesis
• And sucrose transport
“Sink strength” determines where sucrose goes
Rate depends on “phloem loading” by sucrose
Transporters and other unidentified factors
Phloem Unloading
Source cells control overall supply: decide allocation to
sucrose vs starch
But: are sensitive to sinks, PS goes up if sinks get stronger
Sucrose represses PS genes
Phloem Unloading
Source cells control overall supply: decide allocation to
sucrose vs starch
But: are sensitive to sinks, PS goes up if sinks get stronger
Sucrose represses PS genes
Rest of plant doesn’t need it
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down light & dark rxns
• Inhibits growth
Processes affected by [Sugar]
Photosynthesis
• Sugar turns down
light & dark rxns
Inhibits growth
Induces senescence
Plants and Temperature
Affects enzymes
Plants and Temperature
Affects enzymes: too slow if cold, denature if too hot
Plants and Temperature
Affects enzymes: too slow if cold, denature if too hot
• Rubisco activase is very T sensitive; way to limit PR?
Plants and Temperature
Affects enzymes
Affects membranes
• fluidity
Plants and Temperature
Affects enzymes
Affects membranes
• Fluidity: must be correct
• Too stiff, may leak if too cold
Plants and Temperature
Affects enzymes
Affects membranes
• Fluidity: must be correct
• Too stiff, may leak if too cold
• Denature if too warm
Plants and Temperature
Affects enzymes
Affects membranes
• Fluidity: must be correct
• Too stiff, may leak if too cold
• Denature if too warm
• PSII denatures first!
• Lipids & proteins denature
Plants and Temperature
• PSII sets Topt & upper limit for C4 plants
• Topt for C3 also depends on photorespiration -> varies
with pCO2
Plants and Temperature
• PSII sets Topt & upper limit for C4 plants
• Topt for C3 also depends on photorespiration -> varies
with pCO2
• Have respiration compensation point
Plants and Temperature
• PSII sets Topt & upper limit for C4 plants
• Topt for C3 also depends on photorespiration
• Limiting factor varies at lower T depending on which
enzymes fall behind -> rubisco usually limits C3
Plants and Temperature
Heat dissipation
• Long wave-length radiation
• Sensible heat loss
• Conduction &
convection to cool air
• Evaporation
Transition to Flowering
Can be affected by T
• FLC blocks flowering in fall; after 20 days near 0˚C
plants make COLDAIR ncRNA
FLC blocks flowering in fall; after 20 days near 0˚C plants
make COLDAIR ncRNA: Targets Polycomb Repressor
Complex 2 to
FLC locus &
makes
H3K27me3 ->
silences gene
Transition to Flowering
Can be affected by T
• FLC blocks flowering in fall; after 20 days near 0˚C
plants make COLDAIR ncRNA ->PRC2 silences FLC
• Can then flower
next spring
Transition to Flowering
Can be affected by T
• FLC blocks flowering in fall; after 20 days near 0˚C
plants make COLDAIR ncRNA ->PRC2 silences FLC
• Can then flower next spring
• PIF4 activates
flowering @ high T
by inducing FT
mRNA
(ind of daylength)
Transition to Flowering
Can be affected by T
• PIF4 activates flowering @ high T by inducing FT
mRNA (ind of daylength)
• Plants vary widely in how high T influences flowering
Growth regulators
1.Auxins
2.Cytokinins
3.Gibberellins
4.Abscisic acid
5.Ethylene
6.Brassinosteroids
All are small
organics: made in
one part, affect
another part
Growth regulators
All are small organics: made in one part, affect another part
Treating a plant tissue with a hormone is like putting a dime in a
vending machine. It depends on the machine, not the dime!
Auxin
First studied by Darwins!
Showed that a
"transmissible influence"
made at tips caused bending
lower down
Auxin
First studied by Darwins!
Showed that a
"transmissible influence"
made at tips caused bending
lower down
No tip, no curve!
Auxin
First studied by Darwins!
Showed that a "transmissible influence" made at tips caused
bending lower down
No tip, no curve!
1913:Boysen-Jensen showed that diffused through agar blocks but
not through mica
Auxin
1913:Boysen-Jensen showed that diffused through agar blocks but
not through mica
1919: Paal showed that if tip was replaced asymmetrically, plant
grew asymmetrically even in dark
Auxin
1913:Boysen-Jensen showed that diffused through agar blocks but
not through mica
1919: Paal showed that if tip was replaced asymmetrically, plant
grew asymmetrically even in dark
Uneven amounts of "transmissible influence" makes bend
Auxin
1919: Paal showed that if tip was replaced
asymmetrically, plant grew asymmetrically even in
dark
Uneven amounts of "transmissible influence" makes
bend
1926: Went showed that a chemical that diffused
from tips into blocks caused growth
Auxin
1919: Paal showed that if tip was replaced
asymmetrically, plant grew asymmetrically even in
dark
Uneven amounts of "transmissible influence" makes
bend
1926: Went showed that a chemical that diffused
from tips into blocks caused growth
If placed asymmetrically get bending due to
asymmetrical growth
Auxin
1919: Paal showed that if tip was replaced
asymmetrically, plant grew asymmetrically even in
dark
Uneven amounts of "transmissible influence" makes
bend
1926: Went showed that a chemical that diffused
from tips into blocks caused growth
If placed asymmetrically get bending due to
asymmetrical growth
Amount of bending depends on [auxin]
Auxin
1919: Paal showed that if tip was replaced
asymmetrically, plant grew asymmetrically even in
dark
Uneven amounts of "transmissible influence" makes
bend
1926: Went showed that a chemical that diffused
from tips into blocks caused growth
If placed asymmetrically get bending due to
asymmetrical growth
Amount of bending depends on [auxin]
1934: Indole-3-Acetic acid (IAA) from the urine of
pregnant women was shown to cause bending