Phylogeny Of Rhizobia Isolated From Vigna Plants Of China

Cowpea rhizobia, peanut rhizobia and mung bean rhizobia all belong to "Vigna" rhizobia phylogenetically. However the phylogeny of these rhizobia was poorly understood. In this work, the phylogeny of 35 rhizobial strains isolated from peanut, cowpea and mung bean in different geographical regions of China were investigated through phynotype test and phylogenic analysis on the sequences of 16S rRNA, 16S-23S rDNA IGS, atpD and glnII genes.Phynotype studies showed that all the rhizobia tested and reference strains were clustered into three groups (I, II, III) at the similarity level of 79%. Group I contained rhizobia isolated from Anhui, Hubei, Henan, Hebei, Heilongjiang, Guangxi, Shandong, Jiangsu and reference strain B. yuanmingense. Group II contained rhizobia isolated from Xinjiang, Sichuan, Hubei, Henan, Anhui, Hebei and reference strain B. liaoningense. Group III contained rhizobia isolated from Hebei, Guangxi, Hubei and reference strains B. japonicum and B. elkanii. Phynotype studies indicated that all the rhizobia tested showed abundant biodiversity, and their phylogenetical classification was closely associated with original soil sources.Phylogenetical analysis based on the sequences of operon revealed that all strains tested belonged to Bradyrhizobium at the level of genera. Most of rhizobia tested were closely related to B. yuanmingense and B. liaoningense.Further more, phylogenetical analysis was carried out on the two selected house-keeping genes, atpD and glnII. It demonstrated that all strains tested belonged to Bradyrhizobium at the genera level as well. Most of rhizobia tested were closely related to B. yuanmingense and B. liaoningense.In a summary, all the "Vigna" rhizobia tested belonged to Bradyrhizobium at the genera level, and they could mainly be classified into two groups, B. yuanmingense and B. liaoningense, at the level of species. The phylogenetical classification of some rhizobia tested was not consistent with in different method, which implied there was gene transferration within the species of the same genera.