Biochemical Mechanism of Regulation of Phytochrome Interacting Factor 1 by Light

University Of Texas At Austin, Austin TX

Investigators

Abstract

PI: Enamul Huq Proposal # 0822811 Title: Biochemical Mechanism of Regulation of Phytochrome Interacting Factor 1 by Light Growth and development are highly regulated by environmental light signals at all phases of a plant's life cycle. Plants have evolved several light receptors including the phytochrome (phy) family of photoreceptors to monitor the red and far-red light, the cryptochromes, the phototropins and the ZTL/FKF1 family of F-box proteins to monitor the UV-A and blue light, and an unidentified receptor to monitor the UV-B light. Although much has been learned on these photoreceptors, the primary biochemical mechanism by which they regulate plant growth and development is still unknown. In recent years, degradation of transcription factors both in the dark and light has been shown to play central roles in the light signaling pathways. In general, one class of light signaling factors are degraded in the dark. They include HY5, LAF1 and HFR1, most of which are positive regulators of photomorphogenesis. The second class factors are degraded in light. This class includes Phytochrome Interacting Factors(PIFs), most of which negatively regulate photomorphogenesis. Although, the mechanisms of dark-induced degradation are well investigated, the light-induced degradation of PIFs is less well understood. This project is focused on investigating the early events in the light-induced degradation of the bHLH transcription factor, PIF1, using biochemical, molecular and genetic approaches. PIF1 is rapidly degraded under both red and far-red light conditions. Light-induced proteolytic removal of PIF1 relieves the negative regulation by PIF1 and promote seed germination, chlorophyll biosynthesis and hypocotyl growth inhibition. Since PIF1 is a primary phytochrome-signaling partner, whose stability is regulated by phytochromes through direct physical interaction, the results from this project will provide fundamental information on the mechanism of phytochrome regulated developmental pathways. This study will have broad implications in several ways. First, understanding the biochemical mechanism of regulation of PIF1 in plants will provide fundamental knowledge and molecular tools applicable in agricultural biotechnology for enhanced crop and biomass production. Second, the results and the research tools will be distributed to the community through publications, conference presentations, and website postings directly from our laboratories. Third, this project will contribute to training the next generation scientists in modern functional genomics and molecular genetics, including undergraduate, graduate and postdoctoral students. This training will provide them with the unique opportunity to make significant contributions to the field of plant biology and biotechnology and will prepare them for future careers as independent researchers.