长期适应多种胁迫，“造就”了铁皮石斛独特的生态型和保健性。我们发现，铁皮石斛有极强的抗寡氮胁迫活性，固氮菌丰富，推测固氮菌和高效氮同化是其抗寡氮胁迫的重要策略。阐明该假说有助于揭示铁皮石斛胁迫-抗逆-品质的辩证关系。. 项目以高抗逆性铁皮石斛品系为材料。在确定适宜的寡氮胁迫水平后，基于宏基因组测序分析寡氮胁迫铁皮石斛的固氮菌种群结构、时空分布，分析铁皮石斛的固氮菌资源；基于宏转录组测序，研究铁皮石斛响应寡氮胁迫的差异表达基因，解析氮同化基因及其对寡氮胁迫的应激动态，探索铁皮石斛适应寡氮胁迫的分子机制，为铁皮石斛等濒危资源的有效保护和高效应用提供新思路。

Multiple stresses especially low nitrogen result in the excellent survivability and phamaceutical value of the rare Dendrobium officinale. In our previous experiments, we found that D. officinale grow well under low nitrogen and contained abundant nitrogen-fixer, nitrogen-fixers and nitrogen assimilation might be the ways for the plant to resist to the stress. To demonstrate this hypothesis will be conducive to reveal the ecological significance. .In this project, highly resistant D. officinale cultured with low nitrogen will be the main materils. After deciding the proper low nitrogen, the structure and variation of diatrophic bacteria will be investigated based on the methods of metagenome, which will help to uncover the diatrophic resources. Based on the means of meta transcriptome, the genes in response to low nitrogen will be analyzed, including those regulate nitrogen-fixers and synthesis of polysaccharide, so as to understand clearly the mechanism of the plant resistant to nitrogen stress. This project focuses on the mechanism of the plant in response to low nitrogen, which might provide a novel way to protect and utilize well the rare medicinal plants.