Regulation of Chlorophyll Biogenesis by Phytochrome A.

The photosynthetic apparatus accomplishes two major functions in plants - solar energy conversion and protection of the plant from photodestruction. Its highly orchestrated formation includes coordinated biosynthesis of chlorophyll (Chl) and of its binding to matrix proteins. Light plays here the central role driving both metabolic and regulatory processes. The regulation is achieved via operation of sophisticated photoreceptor machinery with the phytochrome system as its main component. This review concentrates on Chl a biosynthesis and the role of phytochrome A (phyA) in this process. The mechanism of action of phyA and the specificity of its state in the plant has been described, in particular, the existence of two native types with different modes of action. This review touches upon the dependence of the effects of phyA on tissues and organs of the plant and its species, genetic modifications, and hormonal status.