Studies On The Genetic Diversity And Stress Resistance Of Rhizobia Isolated From Robinia Pseudoacacia In Different Provenance

57 strains rhizobia isolated from Robinia pseudoacacia L in 19 different provenance grown in Baoding,Gaoyi and Shahe,they were analyzed using 16S rRNA PCR-RFLP polymorphism and the sequence analysis of 16S rRNA gene for genetic diversity and phylogenic study.30 Robinia pseudoacacia rhizobia were tested by stress resistance indexes,and selected some strains had strong resistance.57 tested strains and 6 reference strains were generated 39 genetic map patterns using 16S rRNA PCR-RFLP polymorphism.Some strains had the same genetic map,and most strains isolated from the same region.The results indicated that Robinia pseudoacacia rhizobia affected by the environment to show differences in regional distribution.Cluster analysis showed that there existed a high degree of genetic diversity for the Robinia pseudoacacia rhizobia.Most strains separated by region,and had not the tendency to cluster for Robinia pseudoacacia provenance.Genetic diversity influenced by the geographical environment.Correlation analysis showed that there was no significant correlation between genetic distance and geographic distanc among provenances.Sequencing analysis of 16S rRNA revealed the representative strain GY-2 shared 99.6% sequence Similarity with S.morelense LMG20571,and belonged to Sinorhizobium in the phylogenetic classification status.Further proved the symbiotic nitrogen fixation of Robinia pseudoacacia and rhizobia with the difference of regional geographical environment.30 Robinia pseudoacacia rhizobia were tested by stress resistance indexes,the results showed that Robinia pseudoacacia rhizobia had wider rang of adaption for growth environment.7 strains can grow in YMA medium with 50 g/L NaCl,and had strong salt resistance.25 strains can grow in YMA medium with pH 12.0,and had strong alkali resistance.20 strains can grow in YMA medium with 37℃,and had a certain degree of heat resistance.43.3% strains had resistance to Ampicillin with 50μg/ml.12 strains have strong resistance were selected,they can grow in YMA medium with 40 g/L NaCl and pH 12.0.These strains can be inoculated with Robinia pseudoacacia which growed in saline land to promote growth.