Genetic Diversity of Chickpea-nodulating Mesorhizobium Species Native to Irania Soils

Using rhizobial inoculants in legumes cropping including chickpeas has attracted attentions because of economic advantages, decreasing chemical fertilizers utilization, and environmental health issues. Iran has 10 years of experience on production and utilization of these inoculants. For production of any rhizobial inoculant, it is vital to have a collection from effective and well-known strains of rhizobia. The aim of the current study was to characterize the isolates of chickpea rhizobia (collected by Soil and Water Research Institute from different parts of Iran) and to evaluate their genetic diversity. Bacterial isolates were purified on YMA plates and were subjected to microscopic, morphological, and plant infection analyses. Out of 120 isolates, 82 were able to nodulate the host plants and were considered as nod⁺ isolates. Identification of the isolates was carried out using biochemical test including utilization of carbohydrates, amino acids, and ability for growth in different cultural conditions. Results of the biochemical tests were used for clustering of isolates. Results showed that, the isolates could be divided into six groups, of which the majority belonged to M. ciceri. Six representatives were selected from each cluster and their 16 rRNA sequence was determined. Results of the study revealed that isolates C-22, C-35, C-35A, C-97 and C-105 belong to M. ciceri and the isolate SWRI-9 was M .mediterraneum.