Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2010
Publication Date: May 1, 2011
Citation: Warburton, M.L., Brooks, T.D., Windham, G.L., Williams, W.P. 2011. Identification of novel QTL contributing resistance to aflatoxin accumulation in maize. Molecular Breeding. 27:491-499. Interpretive Summary: The toxic metabolic product aflatoxin produced by the saprophytic fungus Aspergillus flavus (Link:Fr) in maize (Zea mays L.) can cause health and economic harm when levels exceed very minute quantities. Breeding for maize cultivars that are resistant to aflatoxin accumulation can be an economical and environmentally friendly manner to reduce the toxin, and thus the problem. However, the trait is very complicated and selection for resistant cultivars has been slow. Finding regions of the chromosome that contribute to the trait and then selecting directly at the level of the DNA, rather than at the level of the plant following inoculation to see which maize plants are susceptible and which resistant, may speed breeding progress for this trait. In this paper, we report many chromosomal regions associated with resistance to aflatoxin accumulation, which could improve the trait by up to 55% compared to lines without these chromosomal regions.
Technical Abstract: The toxic metabolic product aflatoxin produced by the saprophytic fungus Aspergillus flavus (Link:Fr) in maize (Zea mays L.) can cause health and economic harm when levels exceed very minute quantities. The selection of resistant germplasm has great potential to reduce the problem, but the highly quantitative nature of the trait makes this a difficult endeavor. The identification of aflatoxin accumulation resistance quantitative trait loci (QTL) from resistant donor lines and the discovery of linked markers could speed this task. To identify marker-trait associations for marker-assisted breeding, a genetic mapping population of F2:3 families, was developed from Mp715, a maize inbred resistant to aflatoxin accumulation, and T173, a susceptible, southern adapted maize inbred line. Large effect QTL were identified in multiple years on chromosomes 1, 3, 5, and 10, and smaller QTL identified in only one year were found on chromosomes 2, 4, and 9. The phenotypic effect of each QTL ranged from 2.0% to 18.5%, and models created with multiple QTL could explain up to 54.5% of the phenotypic variation across years, indicating that the majority of the variation associated with the trait can be accounted for using molecular markers.