Quantitative trait loci for resistance to maize streak virus disease in maize genotypes used in hybrid development

Maize streak virus disease is an important disease of maize in Kenya. In this study, we mapped and characterized quantitative trait loci affecting resistance to maize streak virus in maize populations of S4 families from the cross of one resistant MAL13 and one susceptible MAL9 recombinant inbred lines. Resistance was evaluated in replicated field trials under artificial inoculation while selecting using microsatellite markers. The method of composite interval mapping was employed for QTL detection with a linkage map based on 13 polymorphic microsatellite markers. Phenotypic variances for maize streak virus resistance were highly significant in the population, where the three families were selected. The three families expressed acceptable levels of resistance (1.0 - 1.5) with virus pressure. The three QTLs were for umc2228 with LOD score of 27.7 and explained 93% of the variance, umc2229 with LOD of 13 and explained 78.9% of the variance, and bnlg1832 with LOD of 18.7 and explained 71.3% of the variance. A total of 95% of the lines in the three families were found to be resistant to maize streak virus disease.