Rhizobia are used extensively in agricultural and agroforestry systems for increasing the ability of legumes to fix N2. Knowledge of the classification, genetic characterization and biodiversity of the native rhizobia population is necessary for the selection of inoculant strains. In this work the genetic diversity of 48 rhizobia isolated from root nodules of alfalfa, cultivated in different regions of Iran, was studied by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified intergenic region (IGS) and 16srRNA gene. Analysis of the intergenic region between 16S and 23S rDNAs (IGS) showed a considerable diversity within these microsybionts. At the similarity of 70%, these rhizobia were clustered in to 4 groups:I, II, III and IV. Two genera,Sinorhizobium and Agrobacterium were identified among the isolates by PCR-RFLP of 16srRNA gene.
