植物叶片衰老是叶片生长发育的最后阶段，是植物根据叶片生长发育状态、代谢产物、激素水平以及所处环境条件主动激发并严格调控的复杂过程。光在植物叶片衰老过程中具有重要调控作用，但其调控机制并不清晰。在前期研究中，我们发现拟南芥光信号途径中的重要转录因子FHY3能够显著抑制叶片衰老。在本项目中，我们将利用分子生物学、生物化学及遗传学等多种研究方法，深入解析光信号蛋白FHY3通过直接抑制WRKY28等多个叶片衰老相关基因的表达进而调控叶片衰老的分子机制，建立光信号-FHY3-WRKY28-ICS1/SID2-SA-叶片衰老的信号传递途径。进一步，通过深入研究光信号蛋白FHY3与乙烯信号蛋白EIN3对WRKY28等下游靶基因表达的协同调控机制，建立环境光信号与内源乙烯协同作用调控叶片衰老的分子网络。本研究不仅有助于揭示植物生长发育的基本规律，同时对于重要农作物的衰老调控和产量提高具有重要的借鉴意义。

Leaf senescence is the final stage of the leaf development, which is highly regulated by the internal development signals, plant hormones, metabolites and numerous environmental signals. During leaf senescence, the intracellular components are orderly degraded and the valuable nutrient components are remobilized, which have great impacts on the production and fitness of crop plants. Numerous senescence-associated genes, transcription factors, and the essential components of various hormone and stress signal pathways are involved in the regulation of leaf senescence. Light is one of the most important environmental factors that affect leaf senescence, while the molecular mechanism of how light signals regulate leaf senescence are not fully understood. Our preliminary study indicated that light signal protein FHY3 negatively regulate leaf senescence in Arabidopsis. In this study, we will investigate the molecular mechanism of light signal protein FHY3 in leaf senescence using a variety of methods involved in molecular biology, biochemistry and genetics. We will investigate the synergetic regulation mechanism of FHY3 and ethylene signal pathway transcription factor EIN3 in the transcription regulation of WRKY28, a positive transcription factor that affect the transcription of ICS1/SID2 and the biosynthesis of salicylic acid. Our research will reveal the molecular mechanism of light signal protein FHY3 in leaf senescence, and establish the molecular linkage between environmental light signals and internal ethylene mediated leaf senescence through WRKY transcription factors and salicylic acid. Furthermore, this study will also provide the useful information for the further investigation of leaf senescence in the crop plants.