Phylogenetic diversity of Mesorhizobium in chickpea

Crop domestication, in general, has reduced genetic diversity in cultivated gene pool of chickpea ( Cicer arietinum ) as compared with wild species ( C. reticulatum, C. bijugum ). To explore impact of domestication on symbiosis, 10 accessions of chickpeas, including 4 accessions of C. arietinum, and 3 accessions of each of C. reticulatum and C. bijugum species, were selected and DNAs were extracted from their nodules. To distinguish chickpea symbiont, preliminary sequences analysis was attempted with 9 genes (16S rRNA, atpD , dnaJ , glnA, gyrB, nifH , nifK, nodD and recA ) of which 3 genes ( gyrB , nifK and nodD ) were selected based on sufficient sequence diversity for further phylogenetic analysis. Phylogenetic analysis and sequence diversity for 3 genes demonstrated that sequences from C. reticulatum were more diverse. Nodule occupancy by dominant symbiont also indicated that C. reticulatum (60%) could have more various symbionts than cultivated chickpea (80%). The study demonstrated that wild chickpeas ( C. reticulatum ) could be used for selecting more diverse symbionts in the field conditions and it implies that chickpea domestication affected symbiosis negatively in addition to reducing genetic diversity.