Among the viruses that infect cowpea (Vigna unguiculata L. Walp.), Cowpea severe mosaic virus (CPSMV) and Cowpea aphid-borne mosaic virus (CABMV) are highlighted for their severity and widespread occurrence, respectively. Therefore, the aim of this study was to obtain and evaluate cowpea plants showing resistance to CPSMV and CABMV in order to develop new and essentially derived cultivars. Eight crosses were performed, followed by backcrosses, using the line TE 97-309G-9 and the cultivar Patativa as resistant parental donors, and the cultivars BR3-Tracuateua, BRS-Urubuquara, BRS-Novaera, BRS-Guariba and Pretinho as susceptible parents. Generations F2 and F2RC1 were challenged for resistance by mechanically inoculating CPSMV and CABMV isolates. In F2RC1 generations, besides resistance, other traits were evaluated: number of days to the beginning of flowering, pod length, number of seeds.pod-1, weight of 100 seeds, and yield of seeds.plant-1. All F2 and F2RC1 individuals were analyzed by the χ² test and fit to the expected frequency of 15 susceptible plants: 1 plant resistant to both viruses. The means of resistant F2RC1 plants, from each backcross, were compared with the mean of their respective recurrent parent by the t-test and means of backcrosses were compared by the Scott-Knott test. Genetic variability among backcrosses was detected for all traits. All backcrosses were considered promising for obtaining essentially derived cultivars resistant to CPSMV and CABMV, and the selected plants have characteristics that allow the selection of lines with highly productive grains of good commercial quality.
Vigna unguiculata; Comovirus; Potyvirus; genetic breeding
