Identification and mapping of genetic locus conferring resistance to multiple plant viruses in soybean.

KEY MESSAGE: A reliable locus confers broad-spectrum resistance to multiple plant viruses in soybean under field conditions. Soybean mosaic disease (SMD) can be caused by a variety of viruses, most of which have been largely overlooked in breeding programs. Effective mitigation of the adverse of SMD might result from breeding cultivars with broad-spectrum resistance. However, reports on broad-spectrum resistance to multiple virus have been limited. To catalog viral community members behind SMD, virus samples were collected from symptomatic field plots, and pathogenicity of component strains was assessed. Preliminary ELISA and PCR detection revealed that 39.58% and 66.67% of samples contained two or more virus strains, respectively. Only three soybean accessions were completely asymptomatic, while 42% exhibited moderate or severe susceptibility, indicating that co-infection of multiple virus remains a significant threat in current soybean production systems. Further, a RIL population consisting of 150 F7:9 strains derived from two soybean genotypes with contrasting reactions to virus infection was constructed and explored for significant markers and resistance genes. QTL analysis returned a reliable locus, named GmRmv, on chromosome 13. Significance of GmRmv in imparting resistance to SMD was further confirmed in NIL lines and delimited into a 157-kb interval that contains 17 annotated genes. Among these genes, three, Glyma.13G190000, Glyma.13G190300 and Glyma.13G190400, each contained LRR domains, as well as significant variation in coding sequences between resistant and susceptible parents. Hence, these three genes are considered strong candidate genes for explaining GmRmv significance. In summary, this research opens a new avenue for formulating strategies to breed soybean varieties with broad-spectrum resistance to multiple virus associated with SMD.