Resistance to cowpea mottle carmovirus in Vigna vexillata

Cowpea mottle carmovirus (CPMoV) causes grain yield losses of up to 75% in cowpea (Vigna unguiculata L.] Walp.). There is no resistance to this virus among cultivated cowpea lines, but a high level of resistance exists in Vigna vexillata, a wild Vigna species. Fifty‐four accessions of V. vexillata germplasm collection at IITA were tested for resistance to CPMoV. Seedlings were mechanically inoculated with the virus and susceptibility or resistance was assessed by visual scoring of disease symptoms and serological analysis using antigen‐coated plate enzyme‐linked immunosorbent assay (ACP‐ELISA). All but three V. vexillata lines belonging to the variety angustifolia were resistant to CPMoV. Crosses were made between two resistant V. vexillata lines and the three susceptible lines. Segregation patterns observed in the F₂ and the backcross populations of all the crosses showed that resistance to CPMoV in V. vexillata is controlled by a single dominant gene, and the level of resistance conferred by this gene in V. vexillata is very high.