Peanut drought tolerance and yield enhanced by new Brazilian Bradyrhizobium strains

Abstract The objective of this work was to identify a new Bradyrhizobium strain from Arachis duranensis and to evaluate the effects of different bradyrhizobia strains on the performance of two peanut cultivars under conditions of full irrigation and water stress. The ESA 599, ESA 87, ESA 123, and SEMIA 6144 bacterial strains, as well as the BRS 421 OL and BRS 423 OL peanut cultivars, were evaluated. Strain ESA 599 was identified by the 16S rRNA gene sequence analysis and showed less than 96% of similarity to the closest type strain. Plant growth, nodulation, and gas exchanges were evaluated. Strain ESA 599 is phylogenetically distant from the known type strains, suggesting that it is a member of a new lineage from the Brazilian drylands. The ten-day withholding water period impairs the development of both BRS 421 OL and BRS 423 OL cultivars. The inoculation of ESA 123 and ESA 599 enhances plant growth and gas exchanges parameters, especially when there is no water deficit. The inoculation of ESA 123 and ESA 599 benefits differentially the peanut cultivars in the field, indicating a genotypic interaction between macroand microsymbionts.