Fine Mapping and Candidate Gene Discovery of the Soybean Mosaic Virus Resistance Gene, Rsv4

Abstract

Soybean mosaic virus (SMV) is a prevalent virus infecting soybean ( Glycine max L. Merr) worldwide. The incorporation of Rsv4 , conferring resistance to all currently known strains in the United States, can assist in creating durable virus resistance in soybean. Additionally, lines heterozygous at the Rsv4 locus often express a late susceptible phenotype, showing symptoms only in mid to late vegetative growth. In this study the whole‐genome shotgun sequence (WGS) of soybean was utilized for fine mapping and examining potential Rsv4 gene candidates in two populations. Six markers, designed from the WGS, were used to localize Rsv4 in the same, 1.3‐cM region in both mapping populations, a physical interval of less than 100 kb on chromosome 2. This region contained no sequences previously related to virus resistance, namely nucleotide binding site‐leucine rich repeat gene sequences or eukaryotic translation initiation factors. Instead, sequence analysis revealed several predicted transcription factors and unknown protein products. We conclude that Rsv4 likely belongs to a new class of resistance genes that interfere with viral infection and cell‐to‐cell movement, and delay vascular movement.