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 su sceptible tropical maize inbred, Hi34, and 110 recombinant inbred lines (RI Ls) were produced by single seed descent without selection. The RILs were g enotyped with 116 restriction fragment length polymorphisms (RFLPs) and 4 s imple sequence repeats (SSRs). The same population was also evaluated for r esistance 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 umc 167 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 th e phenotypic variance.