Which phytochrome is most highly expressed in a germinated s

Which phytochrome is most highly expressed in a germinated seed? What do you think this phytochrome controls? This phytochrome is light sensitive, what do you think this means?

Solution

15).

Phytochrome is a light sensitive pigment present in some of the bacteria, fungi and plants. Phytochrome A, phytochrome B and phytochrome E are found to be involved in the seed germination of Arabidopsis. Phytochrome A is mainly responsible for the very low fluence responses (VLFRs) triggered by irradiations of far-red light (ultraviolet and visible radiation). Phytochrome B regulates the R/FR (Red/Far red) effects of low fluence response. Phytochrome E either might be directly involved in the far red photoreception or might be necessary for the phyA mediated response.

These photoreceptor pigments are sensitive to red and far-red light region. The detection of light helps to sense the length of day light and nights, which is necessary for the regulation of flowering time and circadian rhythms. Phytochromes also play a key role in seed germination, seedling size, shape, chlorophyll synthesis, number of leaves, etc.