Phaseolus vulgaris recognizes Azorhizobium caulinodans nod factors with a variety of chemical substituents

Phaseolus vulgaris is a promiscuous host plant that can be nodulated by man y different rhizobia representing a wide spectrum of Nod factors. In this s tudy, we introduced the Rhizobium tropici CFN299 Nod factor sulfation genes nodHPQ into Azorhizobium caulinodans. The A. caulinodans transconjugants p roduce Nod factors that are mostly if not all sulfated and often with an ar abinosyl residue as the reducing end glycosylation, Using A. caulinodans mu tant strains, affected in reducing end decorations, and their respective tr ansconjugants in a bean nodulation assay, we demonstrated that bean nodule induction efficiency, in decreasing order, is modulated by the Nod factor r educing end decorations fucose, arabinose or sulfate, and hydrogen.