1. Life on earth depends on light derived from the sun

2. Photosynthesis Light is required to help water reduce NADP+ PS2 680nm PS1 700 nm ATP NADPH Light energizes jumps in energy potential to get electrons run through an electron transfer chain H2OH2O2H + + 1/2O 2

3. Engelmann experiment What is an action spectrum?? And what is an absorption spectrum??

4. Action spectrum vs. absorption spectrum

5. Directionality of blue light induced bending (Action spectrum)

6. Directionality of blue light induced bending

7. Kinetics of blue light effects Membrane depolarization Hypocotyl elongation Hypocotyl elongation Gene induction

8. Stomata opening regulated by blue light

9. Protoplasts dark Protoplasts blue light

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

11. Blue light induced bending of coleoptiles

12. phot1 (phototropin1) blue light wild-type phot1 mutant

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

14. Phototropism chloroplast stomata movement opening

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

16. darkbluered WT cry1 phyB cry1 : inhibition of hypocotyl elongation is insensitiv against blue light

17. darkblue WT cry1 phyB cry1 : analysis of cry1 mutants and over-producers

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

20. SKOTOMORPHOGENESIS Photomorphogenesis Skotomorphogenesis

21. SKOTOMORPHOGENESIS Skotomorphogenesis Light has an influence on seedling development Photomorphogenesis Skotomorphogenesis  Hypocotyl: long short  Apical hook: closed open  Cotyledons: closed expanded  Chloroplasts: proplastids fully developed  Photosynthesis: no yes

22. Cotyledon expansion Reduced hypocotyl elongation Open apical hook

23. closed apical hook Non-expanded cotyledons Etiolated hypocotyl Is skotomorphogenesis achived via active repression of photomorphogenesis

24. How to perform genetic approaches to decifer light regulation in plants ???

25. How to perform genetic approaches to decifer light regulation in plants ??? Photomorphogenesis in dark grown seedlings Skotomorphogenesis in light grown seedlings Asking simple questions

26. Getting complicated answers !! Short hypocotyl Expanded cotyledons Open apical hook

27. Skotomorphogenesis in the light

28. Functions of cop/det gene products COP1phytochrome chromophore biosynthesis DET1phytochrome B COP9phytochrome A DET2brassinosteroid biosynthesis

29. Dark Light wild-type cop/det mutants COP and DET proteins inhibit photomorphogenesis

30. Strasburger, 2002 Shade avoidance reaction