Characterization of broad-spectrum resistance to Soybean mosaic virus in soybean [Glycine max (L.) Merr.] cultivar "RN-9'

Soybean mosaic virus (SMV) can cause serious yield losses in soybean. Soybean cultivar RN-9' is resistant to 15 of 21 SMV strains. To well-characterize this invaluable broad-spectrum SMV-resistance, populations (F-1, F-2 and F-2:3) derived from resistant (R) x susceptible (S) and RxR crosses were tested for SMV-SC18 resistance. Genetic analysis revealed that SC18 resistance in RN-9' plus two elite SMV-resistant genotypes (Qihuang No.1' and Kefeng No.1') are controlled by independently single dominant genes. Linkage analysis showed that the resistance of RN-9' to SMV strains SC10, SC14, SC15 and SC18 is controlled by more than one gene(s). Moreover, Rsc10-r and Rsc18-r were both positioned between the two simple sequence repeats markers Satt286 and Satt277, while Rsc14-r was fine-mapped in 136.8-kb genomic region containing sixteen genes, flanked by BARCSOYSSR_06_0786 and BARCSOYSSR_06_0790 at genetic distances of 3.79 and 4.14cM, respectively. Allelic sequence comparison showed that Cytochrome P450-encoding genes (Glyma.06g176000 and Glyma.06g176100) likely confer the resistance to SC14 in RN-9'. Our results would facilitate the breeding of broad-spectrum and durable SMV resistance in soybeans.