A Valuable Gene in Suweon 97 Soybean for Resistance to Soybean Mosaic Virus

Abstract

‘Suweon 97’ (PI 483084) soybean [Glycine max (L.) Merr.] from Korea is resistant (R) to all strain groups (G1–G7 and G7A) of soybean mosaic virus (SMV) identified in the USA. The objectives of this study were to determine the number of loci conditioning SMV resistance and the relationships between the Suweon 97 gene and other genes for SMV resistance. Suweon 97 was crossed to susceptible (S) cultivars Essex and Lee 68 for the inheritance study. For the allelism test, Suweon 97 was crossed with SMV resistant cultivars possessing the Rsv1, Rsv3, and Rsv4 genes. The F2 data from R × S crosses showed a good fit to the monogenic ratio of 3[R+Necrotic(N)]:1S. The F2:3 progenies from the R × S crosses exhibited a ratio of 1R: 2 segregating: 1S, indicating that Suweon 97 has a single dominant gene for SMV resistance. The presence of N plants in R × S crosses suggests the Suweon 97 gene for SMV resistance is incompletely dominant. None of the F2 populations and F2:3 progenies from crosses of Suweon 97 with other resistant cultivars having Rsv1 alleles segregated for susceptibility to five SMV strains, suggesting that the Suweon 97 gene is an allele at the Rsv1 locus. Data from crosses with Rsv3 and Rsv4 cultivars exhibited good fit to dihybrid ratios. This digenic segregation verifies that the Suweon 97 gene resides at a locus other than Rsv3 and Rsv4. In contrast to other previously identified SMV resistance genes, none of which are resistant to all SMV strains, Suweon 97 is immune to all SMV strains in the USA, thus a valuable source of genetic resistance. The gene symbol Rsv1-h is proposed for the resistance gene in Suweon 97.