Phytochrome

Phytochrome

Phytochrome is a photomorphogenically active pigment that modulates plant growth and development with respect to incident light intensity and wavelength distribution. It exists in two forms: an inactive, red-absorbing form (Pr),4 and an active far-red-absorbing form (Pfr). When either absorbs light, it is photoconverted to the other. Phytochrome is a dimeric, water-soluble, relatively labile chromoprotein with similar, if not identical, monomers of about 124 kDa each. It is also a relatively low abundance protein, even under the best of conditions. Genetic manipulation of phytochrome expression in plants leads to plants requiring less light and able to divert more energy to the production of fruits and seeds. For its physicochemical characterization, it has therefore been difficult to utilize techniques that require large quantitites of highly purified protein.