Diversity, Genomics and Symbiotic Characteristics of Sinorhizobia That Nodulate spp. in Northwest Argentina.

spp. are legumes with the ability to associate with diverse α-proteobacteria-a microsymbiont-in order to establish nitrogen-fixing root nodules. A previous investigation from our laboratory revealed that the main bacteria associated with in symbiosis in central Argentina (Province of Santa Fe) were quite diverse and belonged to the genera and . To achieve a more extensive view of the local microsymbionts associated with spp., we sampled three different sites in Jujuy and Salta, in northwest Argentina. Matrix-assisted Laser-Desorption-Ionization Time-of-Flight mass spectrometry (MALDI-TOF) typing, 16S-rDNA analysis, and genome sequencing demonstrated that the dominant root-nodule microsymbionts belonged to the genus , with some sequenced genomes related to , , and . An analysis of and markers indicated that, in some of the isolates, horizontal gene transfer appeared to be responsible for the lack of congruence between the phylogenies of the chromosome and of the symbiotic region. These results revealed diverse evolutionary strategies for reaching the current -microsymbiont diversity. What is remarkable beside their observed genetic diversity is that the tolerance profiles of these isolates to abiotic stresses (temperature, salt concentration, pH) were quite coincident with the separation of the sinorhizobia according to place of origin, suggesting possible ecoedaphic adaptations. This observation, together with the higher aerial dry-weight matter that some isolates generated in cv. Marc when compared to the biomass generated by the commercial strain CB3126, distinguish the collected sinorhizobia as constituting valuable germplasm for evaluation in local fields to select for more efficient symbiotic pairs.