The dark side of life:

Skotomorphogenesis

Cells and cell growthMembranes and cell walls Fertilization and

embryogenesis

Seed development and dormancy

Germination

Water transport

Water relations

Plant nutrition

Solute transport

Gene function

Skotomorphogenesis

Three learning goals:

- what is a skotomorphogenesisplant development without lightrequirements:

dark regulated developmenttranscription factors that react to darkness

- photoreceptors and their integration in developmenthow plants “see” light and what happens thenrequirements:

photoreceptor molecules that are sensitive at appropriate wavelengths

- integration of skotomorphogenesis and photomorphogenesisrequirements:

signal transduction apparatus that connects light and dark development

What is not regulated by light ???

And how is it regulated???

SKOTOMORPHOGENESIS

Photomorphogenesis Skotomorphogenesis

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

Light switch in the dark

Cotyledon expansion

Reduced hypocotylelongation

Open apical hook

closed apical hook Non-expanded

cotyledons

Etiolated hypocotyl

Is skotomorphogenesis achived via active repression of photomorphogenesis

How to perform genetic approaches todecifer light regulation in plants ???

How to perform genetic approaches todecifer light regulation in plants ???

Photomorphogenesisin dark grown seedlings

Skotomorphogenesis in light grown seedlings

Asking simple questions

Getting complicated answers !!

Shorthypocotyl

Expanded cotyledons

Open apical hook

Skotomorphogenesis in the light

Dark

Light

wild-type

cop/detmutants

COP and DET proteins inhibit photomorphogenesis

Regulation of skotomorphogenesis by GA

Germination in dark and light