水稻叶片是进行光合作用的主要器官，叶片早衰不利于光合产物和营养物质从源到库的转运，严重影响水稻的产量。申请人前期研究发现，OsAGO2的下调表达会导致叶片早衰，而OsAGO2如何调控叶片衰老的分子机制尚不清楚。本项目通过细胞学、生理、代谢分析，揭示OsAGO2下调表达后叶片衰老的变化特征；用转录组和全基因组甲基化分析筛选OsAGO2直接调控的靶基因；分析OsAGO2的靶基因超表达和敲除株系叶片的衰老特征；进一步用遗传学方法验证OsAGO2和靶基因的互作关系，分析OsAGO2与靶基因的结合序列及结合序列区域的DNA甲基化变化，确定OsAGO2与靶基因的调控模式。通过上述研究阐明OsAGO2调控叶片早衰的机理。

Rice leaf is the main organ for photosynthesis. The leaf premature senescence is not conducive to the transportation of photosynthetic products and nutrients from source to sink tissue, which seriously affects rice yield. Our previous study found that the down-regulated expression of OsAGO2 would lead to premature leaf senescence, while the molecular mechanism of how OsAGO2 regulates leaf senescence is unclear. Through the cytological, physiological and metabonomics analysis, this project would reveal the change characteristics of leaf senescence after down-regulated expression of OsAGO2. The transcriptome and genome-wide methylation analysis were used to screen the target gene directly regulated by OsAGO2, and the senescence leaves characteristics of the over-expression and knock-out strains of the target gene of OsAGO2 were analyzed. The interaction between OsAGO2 and target gene was further verified by the genetic method, and the DNA methylation changes in the binding region sequence between OsAGO2 and target gene were analyzed to determine the regulation mode of OsAGO2 with the target gene. Through the above study, the mechanism of OsAGO2 regulating leaf premature senescence was elucidated.