Legume lectins and nodulation by Rhizobium

Members of the legume lectin gene family were first identified as encoding carbohydrate-binding proteins from seed extracts, but the distribution and function of the proteins now appears to be much more widespread, During the development of the legume root nodule, lectins are present in at least three distinct locations, and putative functions have been described based on this distribution: at the surface of root hairs, lectins may promote the aggregation of rhizobia in the zone of the root that becomes infected; in the nodule primordium they may stimulate mitotic activity by towering the threshold of response to Rhizobium-derived nodulation factors; and in the central tissue of mature nitrogen-fixing nodules they may function as part of a transient nitrogen reserve. Here, we focus on how lectins might interact with carbohydrates, proteins, membranes and other molecules to influence plant cell morphogenesis and nodule development.