摘要Soybean mosaic virus (SMV) is one of the most devastating viral pathogens of soybean (Glycine max (L.) Merr). In total, 22 Chinese SMV strains (SC1–SC22) have been classified based on the responses of 10 soybean cultivars to these pathogens. However, although several SMV-resistance loci in soybean have been identified, no gene conferring SMV resistance in the resistant soybean cultivar (cv.) Kefeng No.1 has been cloned and verified. Here, using F2-derived F3 (F2:3) and recombinant inbred line (RIL) pop-ulations from a cross between Kefeng No.1 and susceptible soybean cv. Nannong 1138-2, we lo-calized the gene in Kefeng No.1 that mediated resistance to SMV-SC3 strain to a 90-kb interval on chromosome 2. To study the functions of candidate genes in this interval, we performed Bean pod mottle virus (BPMV)-induced gene si-lencing (VIGS). We identified a recombinant gene (which we named RSC3K) harboring an internal deletion of a genomic DNA fragment partially flanking the LOC100526921 and LOC100812666 reference genes as the SMV-SC3 resistance gene. By shuffling genes between infectious SMV DNA clones based on the avirulent isolate SC3 and virulent isolate 1129, we determined that the viral protein P3 is the avirulence determinant mediating SMV-SC3 resistance on Kefeng No.1. P3 interacts with RNase proteins encoded by RSC3K, LOC100526921, and LOC100812666. The recombinant RSC3K conveys much higher anti-SMV activity than LOC100526921 and LOC100812666, although those two genes also encode proteins that inhibit SMV accumulation, as revealed by gene silencing in a susceptible cultivar and by overexpression in Nicotiana benthamiana. These findings demon-strate that RSC3K mediates the resistance of Ke-feng No.1 to SMV-SC3 and that SMV resistance of soybean is determined by the antiviral activity of RNase proteins.