Genetic Diversity of Soybean Nodulating Sinorhizobium Strains from Different Areas in P. R. China Based on Phenotypic and Genetic Markers

Genetic diversity of 30 fast- growing soybean nodulating rhizobial strains were compared on basis of phenotypic and genetic markers: (a) numerical taxonomy, (b) symbiotic performance with selected hosts, (c) RAPDs (Randomly Amplified Polymorphic DNAs), (d) REP (repetitive extragenic palindromic) and ERIC (enterobacterial repetitive intergenic consensus) -PCR fingerprinting, (e) RFLP (restriction fragment length polymorphism) of 16S amplified rDNA, (f) RFLP of 16S–23S rDNA amplified intergenic spacer region (ISR). Numerical taxonomy based on 83 phenotypic characteristics generated a dendrogram in which all the tested strains excepted strain ‘0010–1’ were place in two groups, I and II. Group I was found to be consisted of strains from Xinjiang Autonomous region while group II included 22 strains from other Provinces. Symbiotic performance with selected hosts showed that all the tested strains could nodulated Glycine soja, Glycine max CV. 1809, Aijiaozao, but failed to form nodules on Trifolium repens, Astragalus sinicus, or Medicago saliva. Strains ‘RT18 and RT7’ failed to nodulate Glycine max CV. Heinong 37, and strain ‘92X10’ failed to nodulate CV. Kennong 4. A dendrogram derived from RAPDs corresponded to that based on REP-ERIC PCR fingerprinting. All the tested strains were divided into two groups, I and II. Group I was composed of 7 strains collected in Xinjiang area while group II included 22 strains isolated from other places. Within group II, the strains were further divided into two subgroups, A and B, which clustered at a higher similarity level than do group’s I and II. RFLP analysis of amplified 16S rDNA region revealed 10 kinds combinations of restriction fragment representing 10 genotypes. Similar treatment of 16S–23S rDNA ISR also revealed 10 genotypes. The patterns of the strains from Xinjiang Autonomous Region differed from the other provinces or cities. Seventy-five percent of group II strains generated identical patterns while several strains showed strain specific patterns. The results obtained from different methods showed an identical conclusion that strains from Xinjiang Province were different from the strains collected in other Provinces. Xinjiang’ strains were confirmed to be a separate species under Sinorhizobium. The strains from Heinongjiang and Hubei Province consisted of a tightly homologous cluster separately, on the contrary, strains from Liaonin Province and Tianjin City distributed over two subgroups.