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

ZUBER N.; FORNASERO L.; ERDOZAIN BAGOLÍN, SA; LOZANO M.J.; SANJUAN, J; DEL PAPA M. F.; LAGARES A

Biology

MDPI

Año: 2023

2079-7737

Desmanthus spp. are legumes with the ability to associate with diverse α-proteobacteria—amicrosymbiont—in order to establish nitrogen-fixing root nodules. A previous investigation fromour laboratory revealed that the main bacteria associated with Desmanthus paspalaceus in symbiosisin central Argentina (Province of Santa Fe) were quite diverse and belonged to the genera Rhizobiumand Mesorhizobium. To achieve a more extensive view of the local microsymbionts associatedwith Desmanthus 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-nodulemicrosymbionts belonged to the genus Sinorhizobium, with some sequenced genomes related toSinorhizobium mexicanum, Sinorhizobium chiapanecum, and Sinorhizobium psoraleae. An analysis ofnodA and nodC markers indicated that, in some of the isolates, horizontal gene transfer appeared tobe responsible for the lack of congruence between the phylogenies of the chromosome and of thesymbiotic region. These results revealed diverse evolutionary strategies for reaching the currentDesmanthus-microsymbiont diversity. What is remarkable beside their observed genetic diversityis 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 aerialdry-weight matter that some isolates generated in Desmanthus virgatus cv. Marc when compared tothe biomass generated by the commercial strain Sinorhizobium terangae CB3126, distinguish thecollected sinorhizobia as constituting valuable germplasm for evaluation in local fields to selectfor more efficient symbiotic pairs.