Fine mapping and analyses of R ( SC8 ) resistance candidate genes to soybean mosaic virus in soybean.

Soybean mosaic virus (SMV) in soybean [Glycine max (L.) Merr.] is a destructive foliar disease in soybean-producing countries worldwide. In this study, F(2), F(2:3), and F(7:11) recombinant inbred lines populations derived from Kefeng No.1 × Nannong 1138-2 were used to study inheritance and linkage mapping of the SMV strain SC8 resistance gene in Kefeng No.1. Results indicated that a single dominant gene (designated R(SC8)) controls resistance, which is located on chromosome 2 (MLG D1b). A mixed segregating population was developed by selfing two heterozygous plants (RHL153-1 and RHL153-2) at four markers adjacent to the locus and used in fine mapping R(SC8). In addition, two genomic-simple sequence repeats (SSR) markers BARCSOYSSR_02_0610 and BARCSOYSSR_02_0616 were identified that flank the two sides of R(SC8). Sequence analysis of the soybean genome indicated that the interval between the two genomic-SSR markers is 200 kb. QRT-PCR analysis of the candidate genes determined that five genes (Glyma02g13310, 13320, 13400, 13460, and 13470) are likely involved in soybean SMV resistance. These results will have utility in cloning, transferring, and pyramiding of the R(SC8) through marker-assisted selection in soybean breeding programs.