MutMap-Based Cloning of a Soybean Mosaic Virus Resistance Gene

Soybean is rich in protein and oil and serves as the most important legume crop globally. Soybean mosaic virus (SMV) is a severe threat to soybean production worldwide. MutMap, a gene-mapping technology based on map-based cloning and whole-genome resequencing, is utilized to clone key regulatory genes for agronomic traits in plants. However, no relevant studies have reported the cloning of genes resistant to SMV. We used an M3 mutant population derived from ethyl methanesulfonate mutagenesis of Williams 82, and conducted field inoculation experiments involving the SMV-SC3 strain. After field validation, two lines with high resistance to SMV were finally identified. Using MutMap, we initially screened candidate genes for SMV resistance and found that the G-to-A transitions of one candidate resistance gene, Glyma.13G194900, were at base positions 122 and 166. These transitions resulted in the substitution of glycine with glutamic acid (GGA→GAA) and valine with aspartic acid (GTT→GAT), respectively. Transgenic functional validation in soybean showed that the mutant allele of Glyma.13G194900 (designated Glyma.13G194900^M) substantially enhanced resistance to SMV-SC3, in contrast to the wild-type allele, which did not enhance resistance. Our results demonstrate that MutMap can rapidly identify SMV resistance-related genes to provide a genetic resource that accelerates the breeding of new SMV-resistant soybean.