Abstract Blue Light irradiation of etiolated pea seedling strongly reduces the capacity of a 120 kD plasma membrane- associated protein for subsequent in vitro phosphorylation by added ATP. Experiments are described that will a) provide a complete photobiological characterization of the light reaction; b) investigate the correlation of its photobiological properties with known physiological responses to blue light; c) characterize the phosphorylation change biochemically; and d) characterize the protein itself. The measureable changes in phosphorylation occur in seconds, and the PI will show that progress in these four areas will elucidate early steps in one or more signal-transduction chains from blue light photoperception to final physiological response. Plant growth is controlled by light, both the amount and kind of light it receives. Certain plant growth responses are regulated by high energy blue light. This research will examine the mechanism by which plants perceive light and transform that energy into plant functions.
