An RNase H-Like gene complements resistance to Bean common mosaic necrosis virus in Phaseolus vulgaris.

Bean common mosaic virus and Bean common mosaic necrosis virus (BCMNV) are related positive-sense RNA potyviruses that limit the production of common bean (Phaseolus vulgaris L.) worldwide. Potyviruses infect other legume species, such as Glycine max, which can serve as a source of orthologous resistance genes. The bc-1 on chromosome Pv03 in P. vulgaris and Rsv4 on Gm02 in G. max are syntenic gene regions that confer resistance to Potyviruses. Receptor-like kinases underlie both gene regions, and a linked RNase H-Like protein, which enhances potyvirus resistance, was recently associated with Rsv4. We sought to determine if RNase H-Like encoding genes are similarly located in the bc-1 region and enhance resistance to BCMNV. Synteny analysis between P. vulgaris and G. max revealed RNase H-Like genes near the bc-1 locus. Positional cloning among reference genomes and select genotypes, along with linkage mapping in recombinant inbred line and F populations, identified the RNase H-Like 1 gene, which enhanced resistance to BCMNV NL-3 strain when combined with I, bc-1, and bc-u or with bc-1 and bc-u genes by reducing systemic spread of susceptible symptoms in non-inoculated leaves. A single nucleotide polymorphism marker, G03_4166082, was developed to track the resistant and susceptible alleles for RNase H-Like 1 in breeding programs. Overall, this study advances the understanding of the complex mechanisms underlying BCMNV resistance in common bean.