A novel soybean malectin-like receptor kinase-encoding gene, GmMLRK1, provides resistance to soybean mosaic virus

Soybean mosaic virus (SMV) severely damages soybean [Glycine max (L.) Merr.] yield and seed quality. Moreover, the underlying genetic determinants of resistance to SMV remain largely unknown. Here, we performed a genome-wide association study (GWAS) of SMV resistance in a panel of 219 diverse soybean accessions across four environments and identified a new resistance-related gene, GmMLRK1, at the major resistance locus Rsv4 on chromosome 2. GmMLRK1 encodes a malectin-like receptor kinase (RK) that was induced earlier and to a greater degree in leaves of the SMV-resistant cultivar Kefeng No. 1 than in those of the susceptible cultivar Nannong 1138-2 after inoculation. We demonstrated that soybean plants overexpressing GmMLRK1 show broad-spectrum resistance to both strains SC7 and SC3 on the basis of reduced viral accumulation, increased reactive oxygen species production, and local cell death associated with the hypersensitive response. In contrast, GmMLRK1 knockout mutants were more susceptible to both pathotypes. Haplotype analysis revealed the presence of five haplotypes (H1-H5) within the soybean population, and only H1 provided SMV resistance, which was independent of its tightly linked SMV resistance gene RNase-H at the same locus. These results report a novel gene that adds new understanding of SMV resistance and can be used for breeding resistant soybean accessions.