Molecular diversity of a native mesorhizobial population of nodulating chickpea (Cicer arietinum L.) in Indian soils

Abstract

Chickpea plants with nodules were collected from 32 different farmers' fields of eight districts of Haryana state. In total, 137 mesorhizobial isolations were made from these nodules and authenticated. Finally, 50 mesorhizobia were selected based on nodulation test, growth characteristics, and site of sampling. The molecular diversity of the mesorhizobial population was assessed by PCR-amplified ERIC profiles as well as RFLP of 16S rDNA. Considerable molecular diversity in Haryana soils was observed. Chickpea rhizobia were grouped into six different clusters at the 70% similarity level by both methodologies, but clustering of the strains was different. Considering that each cluster represented a mesorhizobial genotype, Haryana soils showed a high richness index (0.46), and RFLP analysis showed that the mesorhizobial genotype (MG) I was present in 38% of nodules, followed by MG III which was detected in 34% of the nodules. The distribution of different MG in Haryana soils showed that all six types of rhizobia were never present in any of the districts; however, a maximum of five types were present in the Bhiwani district. Rhizobial genotype III was invariably present in all the nodule samples tested.