Soybean mosaic virus (SMV) is one of the major viral pathogens affecting soybean crops worldwide.  Three SMV resistance genes, R_SC4, R_SC8, and R_SC14Q , have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively.  Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China.  In this study, crosses were made between Qihuang 1×Kefeng 1 and Dabaima×Nannong 1138-2.  Ten simple sequence repeat (SSR) markers linked to three resistance loci (R_SC4, R_SC8, and R_SC14Q ) were used to assist pyramided breeding.  Pyramided families containing three resistance loci (R_SC4, R_SC8, and R_SC14Q ) were evaluated by inoculating them with 21 SMV strains from China.  Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing R_SC4, R_SC8, and R_SC14Q .  A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV.  Five F₇ homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection.  The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.  

Soybean mosaic virus (SMV) disease is one of the most destructive viral diseases in soybean (Glycine max (L.) Merr.). SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2:3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines (nILs) derived from residual heterozygous lines (RhLs) of Qihuang 1×nannong 1138-2 were separatively used in the fine mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene (designated RSC3Q) controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat (SSR) markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found flanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that five genes (Glyma13g25730, 25750, 25950, 25970 and 26000) were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection (MaS) in resistance breeding to SMV.