The bright side of life:

Photomorphogenesis

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

SkotomorphogenesisPhotomorphogenesis

Three learning goals:

- what is a photomorphogenesisplant development with lightrequirements:

light regulated developmenttranscription factors that respond to light signals

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

photoreceptor molecules that are sensitive at appropriate wavelengths

- photomorphogenesis during seedling developmentrequirements:

signal transduction apparatus that connects light responses and seedling development

What is not regulated by light ???

SKOTOMORPHOGENESIS

Photomorphogenesis Skotomorphogenesis

Sunflower seedling development in dark and light

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

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

Gene activation through photoreceptors and PIF proteins

Hemara

Photomorphogenesis via protein regulation (protein stability and turnover)

day

night