Fine mapping of the RSC14Q locus for resistance to soybean mosaic virus in soybean

Soybean mosaic virus (SMV) disease is one of the most destructive soybean (Glycine max (L.) Merr.) diseases worldwide, causing yield losses and significant deterioration in seed quality. ‘Qihuang No.1’ has a wide resistance spectrum and is extensively used in breeding programs in China. The dominant SMV resistance gene RSC14Q from the cultivar Qihuang No.1 was previously mapped to a 4.2 cM region on soybean chromosome 13 (formerly linkage group (LG) F). Fine mapping of RSC14Q is essential for high efficiency of marker-assisted selection (MAS) and its map-based cloning. Residual heterozygous lines (RHLs) derived from a soybean recombinant inbred line (RIL) were used to fine map RSC14Q. The RILs were obtained from a cross between ‘Qihuang No.1’ (resistant) and ‘Nannong1138-2’ (susceptible). The genomic sequence in an approximately 6 cM interval between the markers Satt334 and Sct_033 flanking RSC14Q was used to develop five simple sequence repeats and two InDel markers. Linkage analysis between inoculation phenotype and genetic markers localized RSC14Q to the interval between Satt334 and MY750, with genetic distances of 0.6 and 0.5 cM, respectively, corresponding to a physical distance on the ‘Williams 82’ draft assembly (Glyma1.13) of 1.18 Mb. Based on the genes sequences in the RSC14Q locus region with predicted functions for resistance, one SNP marker, MY525, was developed between Satt334 and MY750. Thus, the genomic region containing the RSC14Q was further narrowed to a 616 kb interval.