Phaseolus vulgaris is a non-selective host for nodulation

A systematic analysis of the symbiotic phenotype on Phaseolus vulgaris of tropical rhizobia isolated from a variety of leguminous plant species and of classified type strains from the genera Rhizobium, Sinorhizobium, Mesorhizobium, Bradyrhizobium and Azorhizobium was performed. Depending on the bean cultivar, between 80 and 90% of the tested rhizobia were able to nodulate. A minority of these nodules were also nitrogen-fixing. A detailed microscopic analysis of the induced nodules or nodular structures revealed that the interaction between these strains and P. vulgaris was arrested at different stages of the interaction. Our results show that P. vulgaris is able to perceive signals for nodulation from many rhizobia although most of the interactions are not effective.