Genetic and phenotypic diversity of rhizobia nodulating Chickpea (Cicer arietinum L.) in soils from southern and central Ethiopia

Forty-two chickpea-nodulating rhizobia were isolated from soil samples collected from diverse agro-ecological locations of Ethiopia, and characterized based on 76 phenotypic traits. Furthermore, 18 representative strains were selected and characterized using multilocus sequence analyses (MLSA) of core and symbiotic gene loci. Numerical analysis of the phenotypic characteristics grouped the 42 strains in to four distinct clusters. The analysis of the 16S rRNA gene of the 18 strains showed that they belong to the Mesorhizobium genus. Based on phylogenetic tree constructed from the combined genes sequences (recA, atpD, glnII, and gyrB), the test strains were distributed into four genospecies (designated as genospecies I â IV). Genospecies I, II, and III could be classified with M. ciceri, M. abyssinicae, and M. shonense, respectively while genospecies IV might represent an unnamed Mesorhizobium genospecies. Phylogenetic reconstruction based on the symbiosis-related (nifH and nodA) genes supported a single cluster together with previously described symbiont of chickpea (M. ciceri and M. mediterraneum). Overall, our results corroborate earlier findings that Ethiopian soils harbor phylogenetically diverse Mesorhizobium species, justifying further explorative studies. The observed differences in symbiotic effectiveness indicated the potential to select effective strains for use as inoculants and to improve the productivity of chickpea in the country.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author