茶树CsGS1.1和CsDof5调控成熟叶贮藏氮素循环再利用的分子机制

茶园化学氮肥减施和茶叶品质调控是我国茶业发展的重大科技需求；而贮藏氮素循环再利用的关键调控因子挖掘与机制解析将有助于提高茶树氮素利用率，减少氮肥施用。基于申请人前期发现胞质型谷氨酰胺合成酶编码基因CsGS1.1和转录因子CsDof5在茶树成熟叶贮藏氮素循环再利用中的响应规律和潜在功能，本项目拟以前期筛选获得的三个氮素再利用率差异显著的茶树品种为材料，通过基因表达模式分析、抗体免疫染色细胞学定位、超量表达和突变体回复等手段系统解析CsGS1.1和CsDof5参与成熟叶贮藏氮素再利用的生物学功能；通过酵母单杂交、凝胶阻滞迁移等验证CsDof5是否与CsGS1.1启动子结合，进而调控贮藏氮素再利用；同时挖掘其他参与氮素再利用的CsGS1.1上游调控因子。项目实施将阐明茶树新梢发育过程成熟叶贮藏氮素循环再利用的分子机制，为提高茶树氮素利用率、实现化肥减施与提质增效、促进茶业绿色发展提供理论支撑。

The reduced application of N fertilizer in tea plantation and improvement of tea quality is an important scientific demand for tea production. Exploring the functional roles of genes regulating N remobilization will help to increase the N use efficiency of tea plant and reduce the application of N fertilizer. Previously, we found the potential roles of cytosolic glutamine synthetase gene CsGS1.1 and transcription factor CsDof5 in the remobilization of N from mature leaves to new shoots; and selected three tea cultivars which have significant different N remobilization efficiency by 15N tracing method. In this project, we will confirm the expression patterns of CsGS1.1 and CsDof5 both in mature leaves and new shoots during the sprouting of new shoots in these three tea cultivars. Cellular localization of CsGS1.1 and CsDof5, and over-expression and complementation in planta will suggest their functional roles. Then, yeast one hybrid assay (Y1H), electrophoretic mobility shift assay (EMSA), and ChIP-qPCR will be used to investigate the role of CsGS1.1 in N remobilization regulated by CsDof5 through its binding in CsGS1.1 promoter. Meanwhile, this project will also explore other potential upstream regulators of CsGS1.1 in N remobilization. The expected results from this project will unravel the molecular mechanism of CsGS1.1 and CsDof5 regulating the remobilization of storage nitrogen in mature leaves of tea plant. And also help to increase the N use efficiency in tea plant, reduce the application of fertilizer and improve the tea quality, promote the sustainable development of tea production.