Genetic diversity of rhizobia isolated from Caragana intermedia in Maowusu sandland, north of China

Aims: Thirty-three rhizobial strains isolated from nodules of Caragana intermedia in Maowusu sandland were examined for their genetic diversity and putative phylogenetic position. Methods and Results: Isolates from Caragana intermedia were classified into 12 genotypes by 16S rDNA polymerase chain reaction-restriction fragment length polymorphism (RFLP), which showed no distinct relationships with those of the reference strains. The genotypes of rhizobia were not related to geographical location. Thr 16S rDNA sequence of representative strain GH2001 from dominant genotype 2 shared high homologuey with some Rhizobium species: Rh. giardinii (96.4%), Rh. huautlense (95.3%), Rh. galegae (95.7%), Rh. yanglingense (95.2%), Rh. mongolense (95.6%), Rh. radiobacter (99%) and Rh. rubi (98.3%). Conclusions: A high degree of genetic diversity existed among rhizobia nodulating Caragana intermedia in Maowusu sandland. Most of the new isolates might belong to Rhizobium . Significance and Impact of the Study: The results suggest that the rich diversity of rhizobia might have contributed to the adaptation of the arid region. These strains could be valuable at the economic and ecosystem level.