水稻叶片早衰与产量和品质密切相关，阐明叶片早衰的调控机制对水稻高产、优质十分重要。前期从钴-60辐射诱变籼型水稻恢复系“中恢8015” 得到叶片提前衰老突变体pls1，该突变体在分蘖盛期后叶绿素含量显著降低并提前抽穗；生理学指标测定发现突变体活性氧大量积累、光合速率显著降低。遗传分析表明该性状受隐性单基因控制；图位克隆发现pls1编码一个O-甲基转移酶OsMts1，功能互补pls1突变体能恢复正常表型，但其调控叶片衰老方面的功能和机制未知。本研究将综合遗传学、功能基因组学、植物生理学、生物化学和代谢组学等技术手段，重点研究OsMts1蛋白催化的关键底物分子；结合酵母双杂交及免疫共沉淀技术，筛选并鉴定OsMts1的互作蛋白及其可能的作用机制，旨在阐明该基因调控水稻叶片早衰的分子机制。研究结果可解析OsMts1基因在调控水稻叶片早衰和抽穗期的功能和分子机理，对改良杂交水稻早衰奠定理论基础。

Rice premature leaf senescence is one of the important factors that affect rice yield and quality. It is very important to reveal the leaf-senescence mechanisms to high yield and quality of rice. In this project, a rice mutant with premature leaf senescence (pls1) was obtained from indica-type restorer line ZH8015 via 60Co irradiation treatment. Although normal development in early seedlings, the pls1 mutant displayed earlier leaf senescence with accumulated more reactive oxygen species, less chlorophyll content and photosynthesis rate compared with the wild type after tillering stage. Genetic analysis suggested that the mutant was controlled by a single recessive gene. Fine mapping and position cloning found that the 10th gene fragment was deleted, which encode the O-methltransferase (OsMts1). Although different kinds of leaf senescence-associated genes have been characterized, but methyltransferase regulates leaf senescence were poorly understood in plants. Functional complementation of OsMts1 in pls1 mutant completely restored to wild type. In this project, the biological functions of OsMts1 regulating rice leaf senescence were comprehensively characterized by using genetics, functional genomics, plant physiology, biochemistry and metabolomics tools to identify the key substrate molecules. Besides, the interaction protein of OsMts1 were screened by yeast two-hybrid and confirmed by Co-IP. These results could reveal the function and molecular mechanism of OsMts1 gene that regulates leaf senescence and heading date, which laid the foundation of hybrid rice germplasm improvement.