Mapping of quantitative trait loci conferring resistance to maize streak virus

Maize streak virus (MSV) causes a major disease of maize in Africa. TZi17, a tropical maize inbred with general resistance to MSV, was crossed to a susceptible tropical maize inbred, Hi34, and 110 recombinant inbred lines (RILs) were produced by single seed descent without selection. The RILs were genotyped with 116 restriction fragment length polymorphisms (RFLPs) and 4 simple sequence repeats (SSRs). The same population was also evaluated for resistance to MSV under natural infection in winter 1992 and winter 1993 at IITA, Nigeria. RFLP markers were shown to be linked to a major quantitative trait locus (QTL) on chromosome 1 conferring resistance to MSV through the composite interval mapping. The interval between RFLP marker asg30 and umc167 explained about 29.6% of the phenotypic variance with a peak LOD score of 6.0. A minor QTL for resistance to MSV was also identified and mapped on chromosome 9, with a peak LOD score of 3.0 that explained about 5.9% of the phenotypic variance.