2017 ASHS Annual Conference

Cowpea [Vigna unguiculata (L.) Walp.] (2n=2x=22) is a leguminous crop providing cheap protein for human consumption, growing world-wide. Salinity is one of the major threat to cowpea production, particularly in semi-arid regions of Africa. Salinity significantly affects seed germination and decreases pod and seed yield in cowpea. However, little has been done to provide farmers with salt-tolerant cowpea cultivars. The objectives of this research are to (1) to evaluate cowpea salt tolerance at germination stage, (2) to evaluate cowpea salt tolerance at seedling stage, and (3) to conduct genome-wide association study for cowpea salt tolerance at germination and seedling stages and to identify SNP markers associated with salt tolerance in cowpea. A total of 151 cowpea genotypes at germination stage and 203 cowpea genotypes at seedling stage were evaluated in this research. Association analysis was performed in 116 genotypes at germination stage and 155 genotypes at seedling stage. The results indicated that: (i) a large variability in salt tolerance was found among the tested cowpea genotypes at both germination and seedling stages; (ii) three SNPs, Scaffold87490_622, Scaffold87490_630, and C35017374_128 were highly associated with salt tolerance at germination stage; (iii) seven SNPs, Scaffold93827_270, Scaffold68489_600, Scaffold87490_633, Scaffold87490_640, Scaffold82042_3387, C35069468_1916, and Scaffold93942_1089 were found to be associated with salt tolerance at seedling stage; and (iv) PI582422, 09-529, PI293584, and PI582570 were highly salt tolerant at germination stage and PI293570, PI582812, PI582856, PI180014, PI257463, 09-175, 09-529, PI666260, I582402, and PI582340 were highly salt tolerant at seedling stage. This research will have practical applications in cowpea breeding and genetics. The salt tolerant lines could be used as parents in breeding programs and the SNP markers could be used as tools in cowpea molecular breeding through marker-assisted selection.