花生是我国最重要的油料作物，对花生-花生根瘤菌共生体系的共进化关系和共生互作机制尚不清楚。在已系统研究了我国中部花生根瘤菌多样性的基础上，本研究拟采用多相分类的方法，对我国南部和北部重点花生种植区 (广东，广西和辽宁) 的花生根瘤菌进行系统发育研究，这有助于绘制我国花生根瘤菌种群分布及其与土壤因子关系地图，为科学利用花生根瘤菌提供理论依据，有助于为"我国是花生起源地之假说"提供间接证据，有助于丰富国际根瘤菌分类系统；采用基因组测序技术获得两株新结瘤基因型花生根瘤菌的基因组序列，弥补国际上尚无花生根瘤菌基因组序列报道的空缺，采用生物信息学方法重点分析共生基因序列的系统发育和进化；利用遗传学方法和共聚焦显微镜观察等技术，分析新结瘤基因花生根瘤菌在裂缝侵染和共生互作中的作用，阐明其在与花生的共生互作过程中的功能和机制。

Peanut (Arachis hypogaea L.) is one of the most important edible oil crops in China. Peanut-rhizobia symbiosis in peanut root is a model system for investigating the crack-entry infection way of mutual rhizobia, which mechanism is largly unkown. Using polyphatic taxonomy, we have previously analyzed the phylogeny of the rhizobia associated with peanuts grown in Huang-Huai-Hai Area in China. In the present study, more peanut rhizobia will be collected from other deverse ecoregions including Guangdong, Guangxi and Liaoning provinces and their phylogeny will be analyzed. These data are crucial to mapping the peanut rhizobial population distributions in relation to soil physical and chemical properties all over China and are helpful to apply adaptive rhizobial innoculants in peanut production, discover potential new taxa of rhizobia, and clarify whether peanut is originated in China. Furthermore, the genomes of two new peanut rhizobia will be sequenced to clarify their phylogeny and evolution. Their devergence in nod and nif genes will also be elucidated by comparing their nodulation and nitrogen-fixing genes sequences. Confocal microscopy and genetic techniques will be used to survey the role of the rhizobia with the new nod genes on root colonization, bacterial infection process, bacterial differentiation etc.so as to elicit their functions on the symbiotic interaction between peanut and the rhizobia.