Effect of Cowpea Mottle Virus on Cowpea (Vigna Unguiculata (L.) Walp.) Yield Losses in Burkina Faso

Cowpea production is constrained by several viral diseases all over the world. In Burkina Faso, eight cowpea-infecting viruses were identified using metagenomics-based approaches, including cowpea mottle virus (CPMoV). While this virus, as yet restricted to the Sudan zone, could emerge at the country scale, we aimed in this study to determine the impact of CPMoV on the cowpea yield and to identify resistant cowpea cultivars. Nine cultivars provided by the INERA-CREAF (Institut de l'Environnement et de Recherches Agricoles) breeding program were screened by mechanical inoculation in the field during two years of the trial using split-splot design. Disease incidence, symptom severity, pods and grain yield losses were assessed. Disease incidence was extremely variable and ranged from 4.17 to 100 %. In addition, three groups of cowpea resistance against CPMoV were defined based on symptom severity, including resistant cultivars (Tiligre and Yiis-yande), susceptible cultivars (Gorom local and Moussa local) and fairly susceptible cultivars constituted by the rest of the cowpea cultivars. Aside from the resistant cultivars, the virus reduced pods and grain yields considerably. Gorom local and Moussa local were the most affected with a reduction of 42.04-76.92 % in pods number and 47.31-79.67 % in grain weight. We also report that CPMoV was not seed-transmitted by the nine cultivars. This is the first report of cowpea yield losses caused by CPMoV in Burkina Faso and the first identification of cowpea resistant cultivars against this virus. The identified resistant genotypes should be popularized and used in breeding programs to develop cowpea resistant varieties in Burkina Faso