MOLECULAR MAPPING OF A MAJOR GENE CONFERRING RESISTANCE TO MAIZE MOSAIC-VIRUS

The objective of this study was to determine the genetic basis of resi stance to maize mosaic virus (MMV). Molecular markers were used to map resistance loci to MMV in a set of 91 maize (Zea mays L.) recombinant inbred lines (RILs), derived from the cross between Hi31 (a B68 conve rsion resistant to MMV) and Ki14 (a Thai inbred susceptible to MMV). T he RILs were evaluated for MMV resistance in disease nurseries in Hawa ii in the winter of 1993 and the summer of 1994. Twenty-eight highly s usceptible RILs were chosen for gene mapping using the pooled-sampling approach. Initial evidence from the pooled DNA indicated that restric tion fragment length polymorphism (RFLP) probes on chromosome 3 near t he centromere were biased to the susceptible parent allele. Analysis o f 91 RILs at 103 RFLP loci confirmed the presence of a major MMV resis tance gene on chromosome 3. The resistant allele at this locus, previo usly named Mv1, is present in the resistant parent Hi31 and traces bac k to the Argentine parent used in conferring common rust resistance to B68. We conclude that resistance to MMV in B68 and Caribbean hints in volves a major gene mv1 on chromosome 3 located between RFLP markers u mc102 and php20508.