Phenotypic and genetic diversity of rhizobia isolated from nodules of the legume genera Astragalus, Lespedeza and Hedysarum in northwestern China

Twenty-nine rhizobial isolates from root nodules of the wild Legumes Astragalus, Lespedeza and Hedysarum growing in the northwestern region of China, were characterized by numerical taxonomy, RFLP and sequencing of PCR-amplified 16S rDNA genes, and cross-nodulation with selected Legume species. Based on the results from numerical taxonomy, the isolates could be divided into two main groups (Clusters 1 and 2) and some single isolates at 82% similarity. CLuster 1 contained six isolates from Astragalus, Lespedeza and Hedysarum spp. Cluster 2 consisted of nine isolates from Astragalus and Hedysarum species. The phytogenetic analysis based on 16S rRNA gene sequences showed that SH199, representing cluster 1, belonged to the Rhizobium-Agrobacterium group, and SH290B, representing cluster 2, was closely related to R. galegae and R. huautlense.