Diversity And Phylogeny Of Rhizobia Isolated From Alhagi In The Northwestern Desert Of China

The rhizobial taxonomy and methods used for polyphasic taxonomy were reviewed. Fourty five isolates from nodules of Alhagi. pseudalhagi Desv. in Northwest of China, which are important pioneer plants used as Chinese traditional medicines, were analyzed by phenotypic and genetic analysis such as numerical taxonomy, 16S rDNA PCR-RFLP, IGS PCR-RFLP and phylogenic study (the total sequences analysis of 16S rDNA) .1200 isolates were purified and restored, which were investgated and collected from more than 200 sampling position in 73 counties of Gansu province. These isolates from nodule of 75 species of leguminous plant in 32 genera will made a contribution to amplifing the number of rhizobia resource in the center of Northwest of China. Further, 1200 isolates will be the base of studying on exploring and applying to agricultural production.The physiological and chemical characteristics of all isolates were tested and the results indicated all strains could grow in culture medium of pH9.0 and in the concentration of 50ug/ml phosphomycin, especially, CCNWOX04-1 could grow well in pH5 - pH12, which was one of 9 strains isolated from Alaer, Xinjiang province. Only CCNWOX04-1, CCNWXJ11-2 and CCNWXJ40-1 could grow at 40℃. All unknown rhizobia have special traits which different from other rhizobia have in one place, which could be proved through using some material as sole carbon and nitrogen, and could be proved by which strain could grow in antibiotic. One strain could grow on 1.4mmol/L Zn2+plate and on 600mg /L phenol plate.All the test isolates were divided into 5 groups at the level of 85% by numerical taxonomy. The groupⅠwas fast-growing clusters,which were clustered with reference strains of Rhizobium. The groupⅡ,Ⅲ,Ⅳmay be a new group because in this cluster there were no reference strains included. The group 5 clustered with type strains of M.tianshanesnse at the level of 88%.Thirteen genotypes of fourty-five isolates were obtained in analysis of 16S rDNA PCR-RFLP. There were 3 genetic groups at 89% similarity level. Most isolates were clustered according to different region. Twenty four genotypes were obtained in analysis of IGS rDNA PCR-RFLP. There were 3 genetic groups at 82% similarity level. Twenty five genotypes were obtained in analysis of 23S rDNA PCR-RFLP. There were 3 genetic groups at 87% similarity...