IMPROVED RESISTANCE TO MAIZE-DWARF MOSAIC-VIRUS BY SELECTION UNDER GREENHOUSE CONDITIONS

Maize dwarf mosaic, caused by maize dwarf mosaic virus (MDMV), is the most widespread virus disease of maize (Zea mays L.) in the USA. The o bjectives of this study were to determine the effectiveness of selecti ng for resistance to MDMV under greenhouse conditions and to determine if the resistant selections had a gene, presumably Mdm1, for resistan ce to MDMV that was linked to the endosperm color locus, YI, on Chromo some 6. One resistant selection was developed from each of six differe nt races of corn crossed with a susceptible hybrid, and two additional resistant selections were obtained out of a synthetic developed in Mi ssissippi. AIL selections were resistant in field trials in Mississipp i. All except one had a higher Level of resistance than the field resi stant checks in greenhouse tests in Ohio. Three selections had infecti on levels similar to the highly resistant check inbred, Pa405. Except one, all resistant selections had a gene for resistance linked to the endosperm color locus on Chromosome 6. Apparently, the Mdm1 gene is co mmon in many resistant lines, but the data on one line, Mp92:448, sugg est resistance is possible without this gene.