Soybean preference for Bradyrhizobium japonicum for modulation: Binding to rhizobial cells of lectins isolated from seeds of soybeans with various Rj-genotypes

Caldwell and Vest (1968) planted soybeans (Glycine max L. Merr.) with various genotypes at Beltsville, USA, without inoculating them with Bradyrhizobium japonicum, and showed that soybeans preferred certain serotypes of rhizobial strains for nodulation. Recently, the authors have reported that soybeans carrying nodulation-conditioning genes preferred appropriate strains showing specific behavior for nodulation (Ishizuka et al. 1991). For instance, nodulation of soybean cv. Hardee which carries the nodulation-conditioning genes, Rj ₂and Rj ₃, does not occur with B. japonicum USDA122, USDA33, Is-1, etc. Nodulation of cv. Hill which carries the Rj ₄gene, does not occur with B. japonicum USDA61, Is-21, etc. while A62-2 which carries a recessive gene rj ₁, does not nodulate with almost any of the strains of B. japonicum. Therefore, the B. japonicum strains can be classified into three nodulation types based on the compatibility with these Rj-cultivars, that is, type A strains which effectively nodulated both Rj ₂Rj ₃-cultivars and Rj ₄-ones, type B strains which did not nodulate the Rj ₂Rj ₃-cultivars and type C strains which did not nodulate the Rj ₄-cultivars. When the nodulation types of the isolates from nodules of field-grown soybeans were examined, it was suggested that the Rj ₂Rj ₃-cultivars and Rj ₄-cultivars preferred the type C and type B strains, respectively (Ishizuka et al. 1991).