STEPS TOWARD DEFINING THE ROLE OF LECTINS IN NODULE DEVELOPMENT IN LEGUMES

A number of genes, of both the plant and the bacteria, are specificall y induced upon the interaction between rhizobia and plants during the onset of nodulation. However, many other genes such as those encoding lectin, a protein which has been hypothesized as being involved in hos t recognition by rhizobia, are not specifically induced in response ei ther to rhizobial inoculation or to Nod factor treatment. Exactly how lectin is involved in recognition between rhizobia and legume is still not well understood: To this end, we have isolated and characterized two alfalfa lectin genes from an alfalfa genomic library. Lectin mRNA- antisense alfalfa plants have been generated and the early stages of d evelopment of the transgenic plants have been studied. Differences wer e seen from the control plants with respect to the number of plants fo rmed per callus. We have also transferred the soybean lectin gene into alfalfa as well as into Lotus, and have examined the response of the transgenic plants to inoculation with Bradyrhizobium japonicum, the us ual symbiont for soybean. The combination of these approaches should b ring us to a closer understanding of the role of lectins in nodule dev elopment.