光是影响植物生长发育的重要环境信号。光形态建成过程中的光信号接受、传导以及上游的重要转录因子目前已有较多了解。然而，光信号通路下游事件包括光信号的重要靶标基因以及这些基因如何响应光信号而调节生长发育，了解非常有限。本课题组在前期工作中，发现拟南芥糖基转移酶基因UGT76X的突变对生长发育表型有重要影响，该基因的表达受光信号和生长素调节，突变体和过表达体内生长素糖酯的积累量出现了相反变化。这些结果暗示该基因是光信号的靶标基因并且可能通过生长素参与了光形态建成。本课题计划在此基础上，通过遗传学、生化与分子生物学等手段，进一步研究糖基转移酶基因UGT76X与光信号通路的关系，分析该酶的作用底物，明确该基因参与光调节生长的作用机制。目的是发现糖基化修饰在光形态建成中的重要性，提出光信号途径下游通过糖基化修饰调节植物生长的新机制。该研究对于理解植物光形态建成的分子事件及其作用机制具有重要理论意义。

Light is a key environmental cue controlling plant growth and development. For photomorphogenesis of plants, the reception, transduction and upstream transcription factors of light signaling have been extensively studied. However, the downstream events of light signaling pathway, including target genes and their action modes in regulating plant development, are largely unknown. Our previous work indicated that the Arabidopsis glycosyltransferase gene UGT76X has crucial effect on growth phenotypes. In addition, UGT76X gene was transcriptionally regulated by light signal and auxin, and its mutants and overexpressors gave an opposite change in auxin glucoside level. These results suggest that UGT76X may be a target gene of light signaling and it possibly functions in photomorphogenesis by modulating auxin. Based on these findings, this research project was proposed to study the relationship between UGT76X gene and the light signaling pathway, discover the in vivo substrate of UGT76X enzyme, and analyze the action mode of UGT76X gene involved in the photomorphogenesis through integrated biochemical, molecular and genetic approaches. The research aim is to make clear how important the UGT76X is for the control of photomorphogenesis and get new insight into the mechanism of glycosylation process regulating photomorphogenesis downstream light signaling pathway. Thus, this research would have great scientific significance for understanding the molecular regulation events of downstream light signaling pathway in plants.