作为叶片发育的最后阶段，叶片衰老在植物的生长发育过程中起着重要的作用。由于叶片衰老会引起光合作用和碳同化能力的下降，因而它是作物产量的限制因素之一。在之前的研究中，申请人分离和鉴定一个定位于细胞质膜的半乳糖转运蛋白OsSWEET5，并初步分析了它在调控水稻叶片衰老进程中的作用，但OsSWEET5调控叶片衰老的详细机制并未阐明。本项目拟在各种激素、不同浓度的半乳糖和暗处理条件下，检测OsSWEET5转基因植株中各种激素与各种糖含量的变化，分析各种激素和糖代谢、转运相关基因表达量的变化，并结合OsSWEET5的表达模式和转运活性，以及通过酵母双杂交和BiFC试验检测OsSWEET5的互作蛋白，来阐明OsSWEET5如何调控水稻叶片衰老进程，为进一步揭示水稻叶片衰老机制奠定基础。

As the final stage of leaf development, leaf senescence plays important roles in the process of growth and development of plants. Because leaf senescence can cause the decline of photosynthesis and reduction of carbon assimilation, which makes it a limiting factor for crop yield. In our previous study, a plasma membrane protein involved in galactose transport named OsSWEET5 was isolated and identified, and the role of it in regulating leaf senescence was preliminary analyzed. However, the detailed regulation mechanism of OsSWEET5 in regulating leaf senescence remain to be elucidated. We will investigate the changes of plant hormones and sugar levels, and examine the transcriptional changes of the genes involved in plant hormones and sugar metabolism and transport in OsSWEET5 transgenic plants at various plant hormones treatments, or galactose and dark-induced senescence conditions; analysis the expression pattern and transport activity of OsSWEET5, screen and verify the OsSWEET5-interacting proteins through yeast two-hybrid and BiFC assay, to expound how OsSWEET5 modulates the regulation of leaf senescence in rice. These results will provide us the basic information to further reveal the mechanisms of leaf senescence in rice.