花生根瘤菌群体遗传多样性和系统发育研究

Genetic Diversity and Phylogeny of Rhizobia Isolated from Peanut ( Arachis hypogaea)

利用 16SrRNARFLP、16SrRNA序列分析和 16S～ 2 3SIGSPCRRFLP技术对 4 3株花生根瘤菌和来自其他种属的 15个参比菌株进行了群体遗传多样性和系统分析。 16SrRNAPCRRFLP分析结果表明 ,所有供试花生根瘤菌均属于慢生根瘤菌属 ,在系统发育上与B .japonicum的亲缘关系最近 ,具有相同的 16SrRNARFLP基因型 ,而与B .elkanii相对较远。 16SrRNA序列分析结果表明 ,供试花生根瘤菌在系统发育上更接近于B .liaoningense ,序列间差异小于 1% ,而B .liaoningense在系统发育上与B .japonicum相距很近 ,其序列间差异小于 1%。 16S～ 2 3SrRNAIGSRFLP分析结果表明 ,尽管花生根瘤菌与B .japonicum和B .elkanii的亲缘关系很近 ,但在 71%的相似性水平上供试花生根瘤菌仍各自聚为一群 ,并可进一步分为A、B、C和D 4个亚群 ,该分群还明显反映了地理因素对群体遗传多样性和系统发育的影响。

Forty three rhizobium strains isolated from peanut ( Arachis hypogaea) and 15 reference strains from other genus and species were analyzed by the method of 16S rRNA RFLP? 16S rRNA sequencing and 16S～23S IGS PCR RFLP. The results of the 16S rRNA RFLP shown that 43 strains tested were all ascribed to the genus of Bradyrhizobium phylogenetically. Strains tested were adjacent to the B. japonicum and far from B. elkanii 16S rRNA genotype. The genotypes generated by the 4 restriction endonucleases, Mbo Ⅰ, Dde Ⅰ, Hae Ⅲ and Msp Ⅰ, were same as the representatives of B. japonicum . The dendrogram generated by 16S rRNA sequence and Neighbor joining method shown that peanut rhizobia clustered into the subcluster represented by B. japonicum and B. liaoningense , were more close to B. liaoningense genetically, and the sequence difference between them was less than 1%. High sequence similarity was also determined between B. liaoningense and B. japonicum . JZ1, representative strain of peanut rhizobia were systematically far from the B. elkanii , and the sequence divergence about 2%. The results from IGS RFLP analysis indicated that although they were phylogenetically close to B. japonicum and B. elkanii , peanut rhizobia forming an independent group at the similarity of 71% could be further divided into four subgroups, A, B, C and D. Subgroup A consisted of strains from different region, subgroup B was composed of strains from Wuchang, Qianjiang and Jingzhou, subgroup C was mainly composed of strains from Jingzhou and starins of subgroup D mainly from Neijiang. Reference strains from B. japonicum and B. elkanii were independently clustered intothe subgroup E at the similarity of 71%. The geographical factor effect on genetic diversity of rhizobia was found.