Blue light photoreception plays an important role in the regulation of higher plant development. Blue light photoreceptors mediate directional growth toward the light on the one hand (phototropism) and the extremely rapid inhibition of growth of stem elongation that is a part of the early de-etiolation response of emerging seedlings on the other. There is strong evidence that these two processes proceed through separate and independent signal transduction pathways. The goals of this research are: (1) to isolate, characterize, and obtain sequence information on a plasma membrane protein that is phosphorylated as a consequence of blue light irradiation, and that appears to be involved at an early stage in phototropism, and (2) to isolate, characterize, and obtain sequence information on a protein cross-reactive with several antibodies directed against animal intermediate filament proteins, a protein that may be involved in the rapid inhibition of growth. Arabidopsis thaliana mutants are available in both pathways, making Arabidopsis the organism of choice for these studies. It is expected that complete sequence information will be obtained on these two A. thaliana proteins involved respectively in two different blue light-induced signal transduction pathways. %%% Blue light is an important environmental signal in plant growth and development. It stimulates plants to grow toward light and regulates the elongation of young seedlings as they emerge from the soil. This research will take advantage of the power of molecular genetics to study the structure and role of two specific proteins involved in early stages of the response of plants to blue light. The results will be important contributions to our understanding of the molecular basis of plant responses to the environment.
