Biochemical Mechanism of Regulation of Phytochrome Interacting Factor 1 by Light

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Light is a critical factor regulating plant growth and development. For example, red and far-red light regulate important processes like seed germination and greening. The phytochrome family of photoreceptors monitors the red (R)/far-red (FR) light and initiate these responses. This project will elucidate poorly understood biochemical mechanisms of phytochrome action. Degradation of critical regulatory proteins (transcription factors) both in the dark and light has been shown to play a central role in photomorphogenesis. In general, two classes of light signaling factors are regulated by degradation: Positive regulators of photomorphogenesis such as HY5, LAF1 and HFR1 are degraded in the dark and negative regulators called Phytochrome Interacting Factors (PIFs) are degraded in response to light. Although dark-induced degradation of positive regulators has been thoroughly investigated, light-induced degradation of PIFs is less well understood. This project will use biochemical, molecular and genetic approaches to elucidate early events in the light-induced degradation PIF1 under blue, red and far-red light conditions. Light-induced degradation of PIF1 relieves the negative regulation by PIF1 to promote seed germination and greening, and inhibit hypocotyl growth. The broader impacts of the project include fundamental advances, human resource development, and training. Since PIF1 is a primary phytochrome-signaling partner whose stability is regulated by phytochromes, the project will provide fundamental information on these important processes. Moreover, as transcription factors are critical regulators of all developmental processes, understanding the mechanism of PIF1 regulation will be enabling for agricultural biotechnology and biomass production. Project results and the research tools developed will be distributed through publications, conference presentations, and website postings as well as directly from the laboratory. This project will provide needed training for undergraduate, graduate and postdoctoral students in modern functional genomics and molecular genetics. Finally, aspects of the project will be actively integrated into undergraduate and graduate classroom teaching.