2. Germination of lettuce seeds (photoreversibility)
Reversible R/FR response system controlled by phytochrome (1952)
Taiz-Zeiger 2010

4. Phytochrome: from synthesis to action
red light
germination,
flower
Induction……
synthesis
far red light

5. Phytochrome: homodimeric chromoprotein:
apoprotein and phytochromobilin (open chained tetrapyrrol) as chromophor form holoprotein
Arabidopsis: 5 phytochrome proteins (phyA - phy E),
differ in their apoproteins

6. Bacterial and plant phytochrome structure and function
Taiz-Zeiger 2010

7. PHYA-GFP and PHYB-GFP fusion proteins migrate into the nucleus
Dark Red
PHYA-GFP
PHYB-GFP
Dark Red

8. Phytochrome and GA action mediate light and dark responses
Taiz-Zeiger 2010

9. Light - dark regulation of COP1 activity
HFR1: long hypocotyl in Far-red
LAF1: long after far-red light
SPA1: phytochrome A suppressor
COP1: constitutive photomorphogenesis
HY5: long hypocotyl5
Taiz-Zeiger 2010

11. Life on earth depends on light derived from the sun
PP01021.jpg
Life on earth depends on light derived from the sun

12. Photosynthesis PS1 PS2 Light is required to help water reduce NADP+
Light energizes jumps in energy potential
to get electrons run through an
electron transfer chain
NADPH
PP0103.jpg
PS1
700 nm
ATP
PS2
680nm
H2O
2H+ + 1/2O2

13. Engelmann experiment What is an action spectrum??
And what is an absorption spectrum??
PP0116B.jpg
Engelmann experiment

14. Action spectrum vs. absorption spectrum
PP1804.jpg

15. Directionality of blue light induced bending
(Action spectrum)
PP1804.jpg

16. Directionality of blue light induced bending
PP1804.jpg

17. Kinetics of blue light effects
Hypocotyl
elongation
Membrane
depolarization
PP1804.jpg
Gene induction
Hypocotyl
elongation

19. Stomata opening regulated by blue light

20. Stomata opening regulated by blue light
Protoplasts
dark
Protoplasts
blue light

21. How are light regulation and metabolism interconnected
Zeaxanthin cycle in guard cells

23. Dark and light form of carotenoid protein in stomata opening

25. Measuring irradiation:
chloroplast movements (Lemna) depending
on light intensity
Dunkelheit Schwachlicht Starklicht

26. Blue light induced bending of coleoptiles
PP1804.jpg

27. phot1 (phototropin1)
wild-type
blue light
PP1804.jpg
phot1 mutant

28. PHOT genes in Arabidopsis
LOV-domains change redox status in proteins through (Light, Oxygen, Voltage)
 LOV-domains are flavin binding sites (FMN)

29. Phototropism chloroplast stomata movement opening

30. cryptochrome, together with phytochromes
deetiolation of seedlings
photoperiodic induced morphoses (e.g. flower induction)
circadian rhythms

31. cry1 : inhibition of hypocotyl elongation is insensitiv against blue light
dark
blue
red
WT cry1 phyB
WT cry1 phyB
WT cry1 phyB

32. cry1 : analysis of cry1 mutants and over-producers
dark
blue
WT cry1 phyB
WT cry1 phyB

33. CRY1 shows similarity to prokaryotic DNA photolyases
70%
30%
70%
bacterial
photolyase
Chromophor 1:
Chromophor 2:
MTHF (pterin)
8-HDF (deazaflavin)
FADH-

34. Adduct formation in FMN in PHOT1