Inheritance of resistance to SCMV and MDMV in european maize

Abstract

Sucarcane mosaic virus (SCMV) and maize dwarf mosaic virus (MDMV) cause important virus diseases of maize in Europe. In field and greenhouse experiments, 122 maize inbreds (45 flint and 77 dent lines) were evaluated for their reaction to SCMV, MDMV, and other viruses after artificial inoculation. Three dent inbreds (D21, D32, FAP1360A) displayed complete resistance against SCMV, MDMV, Johnson grass mosaic virus, and sorghum mosaic virus. All other inbreds were either partially resistant (4 lines) or completely susceptible. Resistant inbreds D21, D32, and FAP1360A were crossed with susceptible inbreds F7, KW1292, D408, and D145 to produce four F2 and three backcrosses to the susceptible parent (BC1), and were investigated in two field environments and a greenhouse trial. RFLP and SSR markers on Chromosomes 3, 6, and 10 were used to locate resistance genes against SCMV in the maize genome. These regions are known to confer resistance to other viruses in maize such as MDMV, wheat streak mosaic virus, maize mosaic virus, and high plains virus, and also against different fungi. Segregation of SCMV resistance in F2 and BC1 generations fitted to different gene models depending on the environment. Marker analyses detected two genes designated Scm1 on Chromosome 6 and Scm2 on Chromosome 3. For cross D32×D145, 220 F3 families were tested in two field environments and genotyped with 90 RFLP and SSR markers to detect additional SCMV resistance loci, analyse the relationship to fungal resistances, and investigate the mode of gene action for Scm1 and Scm2. Both Scml and Scm2 displayed an additive mode of gene action and significant additive-dominance interactions. Presently, fine mapping of Scm1 and Scm2 is done employing AFLPs and BC7 families in a “bulked segregant analysis”.