Study On Diversity Of Slow-growing Rhizobia Isolated From Arachis Hypogaea

Studies on diversity and phylogeny of slow-growing rhizobia isolated from Arachishypogaea in China was determined by analysis of phynotype, 16S rDNA PCR-RFLP, 16SrRNA gene sequence, 16S-23S rDNA ITS PCR-RFLP.Results of phenotype test shown that all 55 rhizobia tested and 6 reference strainswere clustered into two groups(â… ,â…¡) at the similarity of 69%. Groupâ… could be dividedinto subgroupâ… A,â… B andâ… C. Subgroupâ… A contained rhizobia isolated from Chongqing,Xiangfan and Taian. Subgroupâ… B contained rhizobia isolated from Xiangfan and Taian.Subgroupâ… C contained rhizobia isolated from Xiangfan. Groupâ…¡also could be dividedinto subgroupâ…¡A,â…¡B andâ…¡C. Subgroupâ…¡A contained rhizobia isolated fromChongqing, Xiangfan and Yancheng. Subgroupâ…¡B contained rhizobia isolated fromXuchang and Chongqing. Subgroupâ…¡C contained 6 reference strains B.japonicumUSDA110, USDA6, USDA122 and B. elkanii USDA76, USDA46 andUSDA86.Results of 16S rDNA PCR-RFLP analysis and 16S rRNA gene sequence revealedthat all strains tested could be clustered into three groups at the similarity of 63%. Groupâ… contained 5 slow-growing rhizobia including TA5, they were relatively far from B.japonicum and B. elkanii phylogenetically. Groupâ…¡consisted of 3 reference strains ofB.japonicum USDA110, USDA6 and USDA122. Groupâ…¢could be divided into twosubgroup. Subgroupâ… contained 42 slow-growing rhizobia including TA2. Subgroupâ…¡contained 8 slow-growing rhizobia isolated from Yancheng and the reference strains of B.elkanii USDA76, USDA46 and USDA86.Results of 16S-23S rDNA ITS PCR-RFLP shown that strains tested could be dividedinto two groups at the similarity of 61%. Groupâ… contained 5 slow-growing rhizobiaincluding TA5. Groupâ…¡contained 6 reference strains B. japonicum USDA110, USDA6,USDA122 and B. elkanii USDA76, USDA46 and USDA86. Groupâ…¢could be dividedinto two subgroup. Subgroupâ… contained 42 slow-growing rhizobia including TA2 whichcould be subdivided into six groups at the similarity of 0.939. Subgroupâ…¡contained 8slow-growing rhizobia isolated from Yancheng. At the similarity of 0.791, YC10 wasseparated from other 7 slow-growing rhizobia. Compared with 16S rDNA PCR-RFLP,ITS RFLP assay shown higher resolution.