Phylogenetic And Genetic Diversity Of Rhizobia Isolated From Glycine Soja In Several Regions Of Northwestern China

In order to investigate the diversity and phylogeny of sixty-two rhizobial strains isolated from root nodules of Glycine soja in gansu province and shaanxi province of China, 16S rDNA PCR-RFLP, BOX-PCR,nodulation genes(nodA PCR-RFLP, nifH PCR-RFLP), 16S rDNA and recA sequences analyses were used in this study.Sixty-two rhizobial strains were indived into six groups based on 16S rDNA PCR-RFLP, which located in three branches (Sinorhizobium, Rhizobium, Agrobacterium ) of the phylogenetic tree of 16S rDNA sequenes. GroupⅠ(AAAA) included forty-four tested strains, about 70% of all the tested strains, distributed in four sampling points, and it belongs to Sinorhizobium.The BOX-PCR fingerprint analysis of Sixty-two strains was indicated into three BOX groups at the level of 49% similarity and six BOX groups at the level of 83% similarity. The strains in six groups were similar to the result of 16S rDNA sequences analysis. However, BOX-PCR homology is litter than 16S rDNA sequence.Bases on sequence of recA and 16S rDNA, two phylogenetic tree were consistency,. except that the homology of typed strains with reference strains in recA sequences phylogenetic tree were less than in 16S rDNA sequence phylogenetic tree. 16S rDNA can provide reliable phylogenetic information but the genetic relationships of the genus may be disrupted genetic recombination between species.nodA results suggest that, in different species of Glycine soja has a relatively conservative of Rhizobium. The tested strains CCNWSX1016, CCNWSX1108, CCNWSX1182 and E. Fredii and E.xinjiangense distributed in same branch . The similatry of All tested strains of the nodA gene in Sinorhizobium branch on the phylogenetic tree were 100%, 98.66%.nifH results show that Glycine soja has a relatively conservative Rhizobium symbiosis genes. Sequence analysis showed that nifH genes in Sinorhizobium branch on the phylogenetic tree. The similatary between nifH sequences of CCNWSX1108 and CCNWSX1182 was 99.58% and the two strains the most closely related to S. Kummerowiae phylogenetically with a sequence similarity of 86.32%; CCNWSX1016 was the most closely related to S. fredii with a sequence similarity of 99.14%.In summary, the results show that the northwestern parts of the genetic diversity of Glycine soja rhizobia are more abundant, but it is mainly Sinorhizobium. The study for the rich diversity of wild soybean rhizobia resources, determine the status of the system provides the basis for classification, strong resistance for the breeding of drought and nitrogen-fixing rhizobia and efficient basis.Took above-mentioned into consideration, our study showed that abundantly genetic diversity exhibited on rhizobia retreived from Glycine soja across diverse region of northwest in China, and that Sinorhizobium was the dominant genera. In addition, for the complement of the richness of diversity in rhizobial resources, the determination of rhizobial phylogenetic tatus, and the seed selection of efficently nitogen-fixing rhizobia with highly resistance and drought tolerance associated with Glycine soja, this paper has profoundly provided a valueble reference and has substantially established a solid basis.