1. The dark side of life: Skotomorphogenesis

2. Cells and cell growth Membranes and cell walls Fertilization and embryogenesis Seed development and dormancy Germination Water transport Water relations Plant nutrition Solute transport Gene function Skotomorphogenesis

3. Three learning goals : - what is a skotomorphogenesis plant development without light requirements: dark regulated development transcription factors that react to darkness - photoreceptors and their integration in development how plants “see” light and what happens then requirements: photoreceptor molecules that are sensitive at appropriate wavelengths - integration of skotomorphogenesis and photomorphogenesis requirements: signal transduction apparatus that connects light and dark development

4. What is not regulated by light ???

5. And how is it regulated???

6. SKOTOMORPHOGENESIS Photomorphogenesis Skotomorphogenesis

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

9. Light switch in the dark

10. Cotyledon expansion Reduced hypocotyl elongation Open apical hook

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

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

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

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

15. Skotomorphogenesis in the light

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

19. Regulation of skotomorphogenesis by GA

21. Germination in dark and light