2. Brassinosteroid mutants show dwarf phenotypes

4. Brassinosteroid signal transduction goes through kinases

5. Phytochrome – the classical photoreceptor

6. Development (realization of a phenotype from a genotype) is controlled by  endogenous factors intercellular regulation  phytohormones  exogenous factors biotic factors abiotic factors

8. Photomorphogenesis Skotomorphogenesis (etiolation)

9. Light has an influence on seedling development Photomorphogenesis  inhibition of hypocotyl elongation  opening of apical hook  cotyledon expansion  chloroplast development DarkLight

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

11. Germination of lettuce seeds (photoreversibility) Reversible R/FR response system controlled by phytochrome germination

12. Pr Pfr Red light Far-red light inactive active Phytochrome dogma

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

14. blue lightred light

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

16. Strasburger, 2002 Structure of phytochrome proteins

17. Phytochrome responses vary with amount of light VLFR: 0.00001 µmol x m -2 LFR: 1-1000 µmol x m -2 Arabidopsis seed germination Lettuce seed germination Anthocyanin synthesis Inhibition of hypocotyl elong. Enlargement of cotyledons Apical hook opening HIR: >1000 µmol x m -2 x s -1

18. Phytochrome responses vary with amount of light Inhibition of hypocotyl elongation HIR: >1000 µmol x m -2 x s -1

19. Phytochrome responses vary with amount of light LFR: 1-1000 µmol x m -2 Lettuce seed germination

20. Strasburger, 2002 Phytochrome in seedlings

21. Strasburger, 2002 Shade avoidance reaction

22. Strasburger, 2002 Shade avoidance reaction

23. Strasburger, 2002 Shade avoidance reaction

24. Strasburger, 2002 Shade avoidance reaction

25. Strasburger, 2002 RFR PR inactive PFR active P FR active P R inactive sensor signal transduction Regulatory function

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

27. Gene activation through phytochrome Nuclear import DNA binding Gene activation

28. Pr Pfr Red light Far-red light Photoequilibrium: 660 nm 80% Pfr 730 nm 2-3% Pfr R/FR Sunlight:1.13 Dusk: 0.8/0.9 Shade of leaves:0.2 inactiveACTIVE !!!

29. Red light Far-red light Pr Pfr Two holoproteins (+chromophore) form a dimer Histidine kinase related Chromophore binding domain IIA IA IIB IB IA IIA IIBIB

30. N-terminal extension Hinge region PAS domain Histidine kinase related 1 Histidine kinase related 2 Chromophore binding domain The Phytochrome apoprotein (-chromophore) is a 125kD monomer Chromophore binding domains Two holoproteins (+chromophore) form a dimer IIA IA IIB IB