1. Processes affected by CO2
1) Pathways that consume CO2
2) pathways that release CO2
3) transpiration & stomatal number

2. Processes affected by [Sugar]
Photosynthesis
Sugars
Energy
Biosynthesis
Storage
Structure
Osmotic regulation
Signaling molecules

3. Processes affected by [Sugar]

4. AtHXK1-Dependent Gene Expression
WT vs. gin2
Sucrose metabolism
Starch biosynthesis
Respiration
Photosynthesis
Photorespiration
Fatty acid synthesis &
mobilization
HXK1/GIN2
Flavonoid synthesis
Cell wall synthesis
Nitrogen metabolism
Defense
ROS scavenging / Detoxification Antioxidant protection
Cytokinin signaling Auxin signaling
Light signaling Ca2+ signaling
Upregulated in gin2
Downregulated in gin2

5. 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)

6. 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

7. 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

8. Processes affected by [Sugar]
Photosynthesis
Sugar turns down light & dark rxns
Affects starch accumulation

9. Processes affected by [Sugar]
Photosynthesis
Sugar turns down light & dark rxns
Affects starch accumulation

10. Processes affected by [Sugar]
Photosynthesis
Sugar turns down light & dark rxns
Affects starch accumulation & degradation

11. Processes affected by [Sugar]
Photosynthesis
And sucrose transport

12. 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

13. 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

14. 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

15. Processes affected by [Sugar]
Photosynthesis
Sugar turns down light & dark rxns
Inhibits growth

16. Processes affected by [Sugar]
Photosynthesis
Sugar turns down
light & dark rxns
Inhibits growth
Induces senescence

17. Plants and Temperature
Affects enzymes

18. Plants and Temperature
Affects enzymes: too slow if cold, denature if too hot

19. Plants and Temperature
Affects enzymes: too slow if cold, denature if too hot
Rubisco activase is very T sensitive; way to limit PR?

20. Plants and Temperature
Affects enzymes
Affects membranes
fluidity

21. Plants and Temperature
Affects enzymes
Affects membranes
Fluidity: must be correct
Too stiff, may leak if too cold

22. Plants and Temperature
Affects enzymes
Affects membranes
Fluidity: must be correct
Too stiff, may leak if too cold
Denature if too warm

23. 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

24. Plants and Temperature
PSII sets Topt & upper limit for C4 plants
Topt for C3 also depends on photorespiration -> varies with pCO2

25. 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

26. 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

27. Plants and Temperature
Heat dissipation
Long wave-length radiation
Sensible heat loss
Conduction &
convection to cool air
Evaporation

28. Transition to Flowering
Can be affected by T
FLC blocks flowering in fall; after 20 days near 0˚C plants make COLDAIR ncRNA
FKF1 b

29. 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

30. 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

31. 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
high T
by inducing FT
mRNA
(ind of daylength)

32. Transition to Flowering
Can be affected by T
PIF4 activates high T by inducing FT mRNA (ind of daylength)
Plants vary widely in how high T influences flowering

34. Growth regulators
Auxins
Cytokinins
Gibberellins
Abscisic acid
Ethylene
Brassinosteroids
All are small
organics: made in
one part, affect
another part

35. 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!

36. Auxin
First studied by Darwins!
Showed that a "transmissible influence" made at tips caused bending lower down

37. Auxin
First studied by Darwins!
Showed that a "transmissible influence" made at tips caused bending lower down
No tip, no curve!

38. 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

39. 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

40. 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

41. 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

42. 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

43. 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]

44. 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