Twenty two Bradyrhizobium peanut strains isolated from the root nodules of peanut growing at four different sites in
Sichuan province,southwest China,were characterized by intrinsic antibiotic resistance (IAR),randomly amplified polymorphic DNAs(RAPDs)and 16S 23S rDNA
PCR RFLP to investigate the
genomic diversity.The results of IAR revealed highly phenotypic diversity among the strains.Seven groups were formed.The strains isolated from the same site appeared different reaction to the antibiotic.All of them were resistant to Neo,Str,Ery,Km,Ap and Spe,and most of them were sensitive to Nal.RAPDs experiments were conducted by using 4 primers including primers 5,14,16 and 17.All tested strains were distinct according to amplified results which could be used to identify strains isolated from different sites.The results of UPGMA clustering of strains based on RAPDs patterns divided the strains into six groups.A pair of PHR and P23S R01 primers was used to amplify the 16S 23S rDNA genes of the strains tested.All the strains produced a band of 2 0kb except three(spr4 1,spr4 2,spr4 4)which were 2 1kb.The amplified products were digested with three 4 base cutting restriction endonucleases.Two to five restriction patterns were obtained with each enzyme.Six genotypes were identified.