| Abstract |
Light regulates various plant developmental processes including seed germination, seedling development, shade avoidance, and flowering. In angiosperm, three different photoreceptor systems consisting of phototropin, cryptochrome, and phytochrome perceive the light information and covey the information to modulate various responses. My research is focused around how phytochromes convey the light information to these various responses. In this project, I investigated the function of PIF3, a phytochrome interacting bHLH transcription factor, in relation with other components. Out of this research, I found that phytochromes activate the degradation of PIF3 through 26S proteasome. This result was significant in two ways. First, it showed that phtyochromes inhibit the function of its interacting transcription factor to modulate the light responses. Second, it showed that the role of phytochrome is closely related with the regulation of protein stability. From the research, I also found that PIL5, another phytohcrome-interacting bHLH transcription factor, is a key negative regulator of light-induced seed germination. Regulation of seed germination has been known since early 19th century, but only limited number of molecular components involved in this process have been identified. My discovery of PIL5 as a key negative component will be recorded as a breakthrough in seed germination research.
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