SNP marker-based genetic mapping of rust resistance gene in the vegetable cowpea landrace ZN016

Cowpea rust, caused by Uromyces vignae, is one of the most destructive foliar diseases in cowpea [V. unguiculata. (L.) Walp]. Deployment of rust-resistant cultivars is the most environment-friendly and effective way to curb this disease. For this purpose, a fundamental step is to map the rust resistance genes in elite germplasm lines. In the current study, one major and two minor QTLs conferring rust resistance were detected in a 119-line recombinant inbred line (RIL) population derived from a cross between the rust resistant line “ZN016” and a susceptible cultivar “Zhijiang 282”, using the state-ofthe-art cowpea iSelect Consortium Array.The major QTL, designated as Ruv1, was mapped to a 12.48 cM interval between the SNP markers 2_01772 and 2_03292 on LG09, which explained 34.8% of the phenotypic variation. The minor QTLs, designated as Ruv2 and Ruv3, were mapped to a 7.01 cM interval on LG7 and a 6.19 cM interval on LG8, which accounted for 13.4% and 11.9% of the phenotypic variation, respectively. This study demonstrates the usefulness of the Consortium SNP Array on complex trait mapping and solidifies the basis for marker-assisted breeding of new cowpea varieties with improved rust resistance.