Phytochrome pigment.?

What is phytochrome pigment?

How does light affect germination?

Does it have to do with the absorption spectra

The extensive researches of scientists at the plant industry station at Beltsville,yale and Duke university and at several research institutes have culminated in the isolation of a blue or yellow green proteinaceous pigment, called phytochrome which is the primary receptor of the visible radiation. These are photosensitive photoreceptor found in almost all flowering plants.It was discovered by Borthwick et al (1952) and isolated by Butler et al (1959) from etiolated seedlings of maize.It exists in two interconvertible states, blue and yellow green,Pr and Pfr. Pfr is associated with cellmembrane while proccurs diffused in cytosol.It causes germination of seeds, inhibit flowering in SDP and in LDP plants.Pr absorbs light at 660nm and is changed to Pfr or P730. The latter absorbs light of 730nm and is changed back to Pr quickly.It is required in seed germination of some olants, bud dormancy, leaf abscisson,synthesis of gibberellins and etylene,prevention of photooxidation,photoperiodism and morphogenesis.Pfr is essential for seed germination.Pr is inactive form whil Pfr is active form.

ok, phytochrome far red (Pfr) reacts to red light and converts phytochrome red (Pr), it reacts to fr light, etc.

Phytochrome a red light photopigment that plays a major role in virtually all aspects of plant growth and development.