A single dominant gene in McCall soybean prevents effective nodulation with Rhizobium fredii USDA257

Summary Rhizobium fredii USDA257 will effectively nodulate Asiatic and unimproved soybean cultivars, such as Peking, but most of the highly selected North American cultivars, such as McCall, produce at most rudimentary, ineffective nodules. In R. fredii USDA 257, a locus containing 6 open reading frames is responsible for this cultivar specific incompatibility. To examine the genetic control of incompatability on the part of the host, the soybean cultivars Peking and McCall were crossed to produce five F₁ progeny. These plants and their selfed progeny were tested for nodulation with USDA257. Resistance to nodulation was found to be conditioned by a single dominant gene. These results indicate that, in soybean, strain specific resistance to nodulation can result from gene(s)-for-gene interactions.