Fine mapping and genetic analysis of resistance genes,Rsc18, against soybean mosaic virus

Soybean mosaic virus (SMV) affects seed quality and production of soybean (Glycine max (L.) Merr.) worldwide. SC18 is one of the dominant SMV strains in South China, and accession Zhonghuang 24 displayed resistance to SC18. The F₁, F₂ and 168 F₁₁ recombinant inbred lines (RILs) population derived from a hybridization between Zhonghuang 24 (resistant, R) and Huaxia 3 (susceptible, S) were used in this study. According to the segregation ratios of the F₂ generation (3R:1S) and the recombinant inbred lines (RILs) population (1R:1S), one dominant locus may regulate the resistance to SC18 in Zhonghuang 24. By using composite interval mapping (CIM), Rsc18 was mapped to a 415.357-kb region on chromosome 13. Three candidate genes, including one NBS-LRR type gene and two serine/threonine protein type genes, were identified according to the genetic annotations, which may be related to the resistance to SC18. The qRT-PCR demonstrated that these genes were up-regulated in the R genotype compared to the control. In conclusion, the findings of this research enhanced the understanding about the R genes at the Rsc18 locus. Moreover, our results will provide insights for designing molecular markers to improve marker-assisted selection and developing new varieties with resistance to SC18.