氮是植物体内含量最大的矿质营养元素，也是农业生产中限制作物生长发育的主要缺素.氮肥的大量施用导致了严重的坏境污染,因此研究植物氮吸收同化的分子机制，培育氮高效作物新品种对保护环境和保证农业的可持续发展具有重要意义。 本申请以一个番茄低氮敏感突变体lnsm1为材料，用图位克隆法分离其相关基因，并用生理和分子生物学方法系统地比较分析突变体与野生型在不同氮素供应条件下各种与氮吸收同化的生理指标和相关基因表达的变化，结合突变体和野生型叶组织细胞学观察结果，揭示LNSM1基因的生物学功能，为培育氮高效新品种提供理论依据和基因资源。

Nitrogen is a largest mineral nutrient in plant,and is also a nutrient mostly limiting crop growth and development in agricultural production.It becomes a serious environmental problem due to over-application of nitrogen fertilizer in agriculture. Therefore, studying the molecular mechanisms of nitrogen uptake and assimilation in plant is very important for protecting enviroment and sustaining development of agriculture. In this application, we use a low-nigtrogen sensitive mutant lnsm1 of tomato as research plant material, and isolate its corresponding gene using map-based gene cloning approach. Futher, the expression patterns of the genes related to nitrogen uptake and assimilation and the physilogical parameters related to nitrogen uptake and assimilation will be determined with physiological and molecular approaches, and they will be comparatively analyzed between lnsm1 mutant and its wild type under the conditons with different nitrogen supply. Finally, the changes of subcellular structures of leaf mesophyll cells of the mutant and wuld type will be investigated under eletronmicrospoces under different nitrigen supply. Taken all together, the bilogical functions of LNSM1 will be illustrated. The results will be useful for understanding the molecular mechanisms of nitrogen uptkae and assimilation in plants and for improvement of nitrogen use efficiency in crops.