我国南北大豆产区慢生大豆根瘤菌的遗传多样性和系统发育研究

利用16S rRNA基因RFLP、16S rRNA基因序列分析以及16S-23S rRNA IGS PCR RFLP技术对分离自我国南北大豆产区的慢生大豆根瘤菌进行了群体遗传多样性和系统发育研究。16S rRNA基因PCR RFLP分析以及16S rRNA基因序列分析结果表明:所有供试慢生大豆根瘤菌可分为B.japonicum和B.elkanii两个类群,其中属于B.japonicum的为优势种群,占供试菌株的91%,属于B.elkanii的仅占9%,多样性水平较低。16S-23S rRNA IGS PCRRFLP研究结果表明:属于B.japonicum的慢生根瘤菌具有较丰富的遗传多样性,在69%的相似性水平上可分为群Ⅰ和群Ⅱ两大类群。群I的菌株以分离自黑龙江和河北等北部区域的菌株为代表,群Ⅱ的菌株以分离自广西和江苏等南部地域的菌株为代表,反映出明显的地域特征。两群菌株在系统发育上均与USDA6、USDA110和USDA122等B.japonicum的模式或代表菌株有差异。

Genetic diversity and phylogeny of soybean bradyrhizobia isolated from south and north region of China

Studies on genetic diversity and phylogeny of soybean bradyrhizobia isolated from south and north region of China were investigated through 16S rRNA gene PCR RFLP, 16S rRNA gene sequencing and 16S-23S rRNA IGS PCR RFLP assays. Results of 16S rRNA gene PCR RFLP and 16S rRNA gene sequencing analysis reveal that strains tested are ascribed into Bradyrhizobium japonicum and B. elkanii species. B. japonicum is the dominant species and accounts for 91% of strains tested, but B. elkanii just up to 9%, which shows poor genetic diversity. Results of 16S-23S rRNA IGS PCR RFLP assays reveal that strains belonged to B. japonicum can be divided into Group I and Group HIIat the 69 similarity. Group I consists of strains from northern China, and Group 1I consists of strains from southern China, which demonstrates geographical effect on genetic diversity of bradyrhzobia. Results of 16S-23S rRNA IGS PCR RFLP further reflects that strains of Group I and Group II are phylogenetically different with type or representative strains USDA6, USDA110 and USDA122 of B. japonicum.