Different effects on Vigna unguiculata plants after the inoculation with strains from two Bradyrhizobium symbiovars

Abstract

The species Vigna unguiculata (cowpea) from the Tribe Phaseolae is indigenous to Africa and was introduced from this continent into some European countries. In a previous work, we analysed the core and symbiotic genes of several slow-growing rhizobial strains nodulating V. unguiculata in a soil from Extremadura. Most of them belong to the genus Bradyrhizobium group I on the basis of the 16S rRNA gene analysis with only one strain belonging to the group II. These two groups also correspond to two different symbiovars on the basis of the nodC gene analysis, genisteae and vignae, respectively. In the present work, we analysed the effect of the inoculation of strains VUPME29 and VUPME10 representative from symbiovars genisteae and vignae, respectively, on V. unguiculata yield and bioactive compounds production. The results showed that plants inoculated with the strain VUPME10 from symbiovar vignae have higher number of nodules per plant, dry shoot weight and N content than those inoculated with the strain VUPME29 from symbiovar genistearum. Also, differences were found in the concentration of some bioactive compounds in leaves of V. unguiculata inoculated with these two strains. This is the first study about the effect of inoculation with strains from different symbiovars in the yield and the bioactive profile of a legume.