1. Ch. 2 Photosynthesis (Ps) and Light

2. C4 Photosynthesis 3 patterns:
C3 Ps
C4 Ps
CAM Ps
Minimize FFF (fatal flaws of fotosynthesis)
C4 photosynthesis

3. C4 leaf anatomy
Kranz anatomy (“wreath:” German):

4. C4 pathway
Mesophyll fix CO2 New enzyme (PEP carboxylase)

5. C4 pathway
PEP carboxylase:
Why called
C4 Ps?

6. C4 pathway BSC: Reaction reversed…. CO2 to Pyruvate to C shuttle!!
Calvin
Cycle
(Rubisco)
C shuttle!!

7. C4 pathway
C fixation & Ps

8. C4 pathway
Advantages?
FFF?

9. Fatal Flaws of Fotosynthesis!

10. C4 advantages Benefits: 1) PEP Carboxylase fix C
Photorespiration: A FFF!

11. C4 advantages
Benefits:
2) CO2 concentrated bundle sheath

12. C4 advantages
A FFF!
Benefits:
3) Less H20 loss.
Stoma C4
Good sucker?

13. C4 advantages Benefits: 4) Decrease Rubisco:
High NUE (nitrogen use efficiency):
Now:
CAM

14. CAM photosynthesis CAM: Crassulaceae: Acid: Leaves Diamorpha smallii

15. Leaf anatomy
Succulent

16. Leaf anatomy
Mesophyll
Cells large:
Vascular bundle sheath

17. CAM pathway
Separates C fixation & Ps
Separation in space: C4

18. CAM pathway
Night:
Stomata open
CO2 fixed:
Malic acid

19. CAM pathway
Acid stored
Leaf pH
Acid drop in
skateboarding

20. CAM pathway
Day
Stomata
Reaction
Ps: Calvin Cycle

21. CAM pathway
Separates C fixation and Ps
Night
Day

22. CAM advantages
1) PEP carboxylase fixes C:
photorespiration

23. CAM advantages
2) Stomata open night. Less water loss!

24. CAM advantages
3) Stomata closed day.

25. CAM variation Dependence on CAM varies Some: CAM & succulence
Aeonium arboreum
Fig. 2.14
More succulence,
More CAM

26. CAM variation Carbon cycling:
Ex, Welwitschia mirabilis (Namib desert S. Africa)
Gymnosperm: 2 leaves!
Some plants
may be 1,000 yr old

27. Comparing C3, C4, CAM plants
Taxa: most plants
C4 plants:
Exs:
Some grasses: Sugar cane (Saccharum spp.)

28. Amaizing Facts*
Corn or maize (Zea mays)
*another corny
Boyd joke.....

29. Comparing C3, C4, CAM plants
Dicots:
Kudzu (Pueraria montana)

30. Comparing C3, C4, CAM plants
Typical C4 plant habitat:
In temperate areas:
winter/spring
summer

31. Comparing C3, C4, CAM plants
% grass flora C4 in N. America
Fig. 2.18

32. Comparing C3, C4, CAM plants
Exs: many cacti (saguaro, cholla)
Saguaro “arms”

33. Comparing C3, C4, CAM plants
Exs: Agave species
Economic use??

34. Comparing C3, C4, CAM plants
Exs: some Crassulaceae (Diamorpha smallii)

35. CAM and Epiphytes
Epiphytes:
Abundant tropical rain forests

36. CAM and Epiphytes Alabama Spanish moss (Tillandsia usneoides)
CAM plant:

37. Comparing C3, C4, CAM plants
Exs: many
(esp. epiphytic ones)

38. Comparing C3, C4, CAM plants

39. Comparing C3, C4, CAM plants
Trait C3 C4 CAM
Max. Ps rate
Fig. 2.12

40. Comparing C3, C4, CAM plants
Trait C3 C4 CAM
Max. growth rate
(optimal conditions)

41. Comparing C3, C4, CAM plants
Trait C3 C4 CAM
Optimum Ps temperature
Fig. 2.11