Regulation of Gene Expression by Phytochrome

Abstract

Abstract

This review deals with the mechanism of Phytochrome action in regulating the expression of other genes. The PhyA and PhyB genes have the overlapping roles or there must be another Phytochrome species which are involved in the Phytochrome induction of CAB expression in these etiolated seedlings when they are exposed to red light. Double mutation of PhyA and PhyB potentially lowered the level of CAB mRNA in etiolated seedlings of Arabidopsis plant when they were induced by a red light pulse. This study suggested that these two genes Phy A and Phy B could be redundant to each other and therefore, other Phytochrome genes like Phy C, Phy D and Phy E could have mediated the expression of CAB in the etiolated seedlings of mutants. It is also clear that the supra-cellular signals could potential control the intracellular rhythmic patterns in a circadian system which is found in most of the plant cells. The processes such as photo-morphogenesis and nuclear gene expression are mediated either directly by this Phytochrome A/B-PIF3 complex or indirectly by modulating the repressor complex systems such as COP, DET, FUS, HY5, etc. The location details about the gene products involved in the transduction mutants for the Phy A and Phy B pathways is not yet studied.

Keywords: Phy A, PhyB, CAB, CUF1, PIF3.