is a fast-growing rhizobial species that can establish a nitrogen-fixing symbiosis with a wide range of legume species including soybeans (). In soybeans, this interaction shows a high level of specificity such that particular strains nodulate only a limited set of plant genotypes. Here we report the identification of a dominant gene in soybeans that restricts nodulation with USDA193. Genetic mapping in an F2 population revealed co-segregation of the underlying locus with the previously cloned gene. The allele encodes a member of the Toll-interleukin receptor/nucleotide-binding site/leucine-rich repeat class of plant resistance proteins that restricts nodulation by strains USDA257 and USDA205, and an allelic variant of this gene also restricts nodulation by USDA122. By means of complementation tests and CRISPR/Cas9-mediated gene knockouts, we demonstrate that the allele also is responsible for resistance to nodulation by USDA193. Therefore, the allele likely provides broad-spectrum resistance to nodulation by many and strains in soybeans.
