Identification And Molecular Tagging Of Two Resistance Genes To Maize Dwarf Mosaic Virus

Maize dwarf mosaic is one of the devastating and widespread viraldiseases caused by Maize Dwarf Mosaic Virus (MDMV) in the world .In recent years it has increased steadily in China and become more and more serious due to the infected cultivars. The most effective way to put the disease under control is to breed and popularize resistant hybrids, which based on resistant materials and understanding the resistance to MDMV. In this study, materials with different background were screened based on the resistance to MDMV. The inbred line SIYI with elite agronomy traits was singled out and its resistance to MDMV was studied. The results obtained were as following:1. Four highly resistant materials, 24 resistant materials and 28 moderately resistant materials to MDMV out of 89 maize germplasm were screened out after rub-inoculation. Tropical and subtropical germplasm in maize were found with the resistance genes by pedigree analysis. The inbred line SIYI is one of the resistant materials with elite agronomy traits.2. The resistance of SIYI was analysized by Mendel genetic model when crossed with susceptible inbred line Mo 17, when investigated at adult stage, 50 FI plants and 141 BCi plants were completely resistant to MDMV. The segregation of resistant and susceptible plants in SIYIxMo17 F2 plants and BC2 plants fitted into 9:7 and 1:3 ratio respectively, which showed SIYI carried two complementary dominant genes responsible for the resistance to MDMV at adult stage.3. Based on maize high-resolution molecular genetic map, SSR markers near the chromosome 3 and chromosome 6 centromere were found linking closely with the two resistance genes after the whole maize genome selection, the conclusion of two complementary dominant genes based on Mendel genetic analysis was verified. The genetic distances between markers and genes were calculated, which showed markersVIIbnlg1600 and phi075 flanking the resistance gene on chromosome 6 were 2-3cM and 4-5cM respectively, markers UMC1527 and UMC2020 flanking the resistancegene on chromosome 3 were 1-2 cM and 5-6 cM respectively.4. The function of the two genes was further studied based on the F2 plants genotype analysis and the comparison of field data investigated at different stage, the gene on chromosome 6 closely related to the resistance reaction at seedling stage when investigated one week later after inoculation.