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 objectives of this study were to determine the effectiveness of selecting for resistance to MDMV under greenhouse conditions and to determine if the resistant selections had a gene, presumably Mdm1, for resistance to MDMV that was linked to the endosperm color locus, YI, on Chromosome 6. One resistant selection was developed from each of six different races of corn crossed with a susceptible hybrid, and two additional resistant selections were obtained out of a synthetic developed in Mississippi. AIL selections were resistant in field trials in Mississippi. All except one had a higher Level of resistance than the field resistant checks in greenhouse tests in Ohio. Three selections had infection 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 common in many resistant lines, but the data on one line, Mp92:448, suggest resistance is possible without this gene.