The specific objective for the research is to identify sequence and structural features of the phytochrome A molecule involved in its regulatory action. During this period the focus on the use of overexpreession of mutagenized phytochrome A in trangenic Arabidopsis to identify functionally important residues. This focus will capitalize on the recently developed transgenic Arabidopsis system which provides an easily scorable hypocotyl length phenotype for loss of function in the mutagenized polypeptide. %%% The significance of this research is that it will help define the mechanism by which the regulatory master switch, phytochrome, controls plant gene expression in response to light.
