氮素(N)是植物最重要的大量营养元素之一，它对于植物的生长和发育及粮食的产量和品质具有重要的调控作用。因此研究植物氮营养利用及响应的分子机制具有重要的科学意义和实际应用价值。硝酸根是植物吸收利用丰度最高的氮源形式，除了作为氮素营养外，硝酸根还可以作为重要的信号分子来调控植物的生长和发育，但对于硝酸根信号如何调控植物地上茎叶生长的分子机制却知之甚少。我们前期结果显示硝酸根信号可以通过激活茎尖分生组织活性来促进植物茎尖生长，而该过程是营养信号核心感受元件——雷帕霉素靶蛋白（Target of Rapamycin, TOR）激酶依赖的，硝酸根可以快速激活TOR激酶，从而促进茎尖分生组织活性。所以本项目拟在此基础上进一步研究TOR感受硝酸根信号和硝酸根-TOR通路调控植物茎尖活性的分子机制，并建立硝酸根调控茎尖生长的完整信号通路，为改造高氮利用率及高品质作物奠定理论基础和提供潜在的分子操纵靶点。

Nitrogen(N) is one of the most important macronutrients that affects plant growth and development, and it is considered to be a major yield- and quality-limiting factor for many crops. Hence, the nitrogen use efficiency and molecular mechanisms of nitrogen signaling attracts intensive attention in plant biologists. Previously, it was reported that nitrate, as a major nitrogen source, has vital roles in regulating plant growth and development. However, it remains largely unknown on the molecular mechanisms of nitrate promotes plant shoot growth and development. Our preliminary data shown that nitrate signaling promotes shoot growth and development through activating the shoot apex cell division and the central nutrient sensing regulator Target of Rapamycin (TOR) is involving in this process. TOR kinase could be activated by nitrate rapidly, and then promote shoot apex activation. In this proposal, we will further explore the molecular mechanisms of TOR sensing nitrate signal and how nitrate-TOR regulates the activation of the shoot apexes. Our aim is to reveal the molecular mechanisms of nitrate-TOR controlling plant shoot growth and to provide potential molecular targets for breeding higher nitrogen use efficiency and quality crops.