Inheritance of Resistance to Soybean Mosaic Virus Strains SC4 and SC8 in Soybean

The objective of this study was to understand the genetic and allelomorphic relationships among different soybean (Glycine max L. Merr.) cultivars with resistance to Soybean mosaic virus (SMV). Twelve resistant (R) soybean cultivars were crossed with a susceptible (S) cultivar (Nannong 1138-2, NY30, NY185, 86-4, or 8101) to determine the inheritance of resistance to SMV strain SC4 or SC8, which were predominant in the Huang-Huai-Hai Rivers Region and Yangtze Valley in China. The R parents were also crossed with each other for allelic analysis of resistance genes from different sources. The results indicated that Ji LD42, Xudou 1, and Yuejin 4 and Qihuang 1, Zhongzuo 229, and NY58 carried a dominant resistance gene for SMV strains SC4 and SC8, respectively, whereas Kefeng 1, PI 96983, Jinda 74, Fendou 56, Dabaima, and Qihuang 22 carried single dominant resistance gene for both SC4 and SC8. The allelism test of the resistance genes to SC4 showed that the resistance genes between Dabaima and Fendou 56, Kefeng 1, and Qihuang 1, between Ji LD42 and Fendou 56, and between Jinda 74 and Zhongzuo 229 were not at the same loci. The study of resistance of F₂ plants and F_2:3 families to SC8 indicated that the single dominant resistance genes in Jinda 74 and Fendou 56 shared a common locus or two closely loci. The resistance genes between Qihuang 1 and Kefeng 1 and between Dabaima and Fendou 56 were not at the same locus for SC8. These results are useful to understand the genetic and allelomorphic relationships among various sources of resistance.