An exoB mutant of Rhizobium sp. is effective in indeterminate nodules of Hedysarum coronarium

Genetic and enzymatic characterization of the exoB mutant of Rhizobium sp reveals that, like other exoB mutants, Cal10 cannot produce UDP-glucose 4'-epimerase. The residual exopolysaccharide (EPS), obtained from Cal10 mutant, is a neutral beta glucan and the galactose forms a part of acidic EPS fraction. ExoB mutant induces effective nodules on sulla, a legume that develops indeterminate types of nodule. EPS is not required for successful nodulation in this symbiotic relationship.