Development of a gene-based marker correlated to reduced aflatoxin accumulation in maize

Aflatoxins are carcinogenic and toxic metabolites produced by the fungus Aspergillus flavus during infection of maize (Zea mays L.) and other seed oil crops. Climatic conditions in the southeastern United States favor A. flavus infection and aflatoxin contamination in maize, making it a major issue for farmers in the region. One of the most promising avenues to combat aflatoxin contamination is the development of resistant maize lines. However, this has proven difficult due to a lack of reliable markers for resistance. Previous studies have identified candidate genes that were differentially expressed in response to A. flavus infection. One gene, encoding a chloroplast precursor, was found to contain multiple polymorphisms that were used to design a marker designated Mississippi Marker 1 (MpM1). The marker differentiates between the resistance and susceptible forms of the allele. This marker was used to screen three populations of F-2:3 mapping families, where it was found to map to chromosome 4 and was associated with a significant effect for resistance to aflatoxin accumulation in the Mp313E x B73 mapping population. Furthermore, the marker MpM1 identified a previously unknown quantitative trait loci for resistance to aflatoxin accumulation on maize chromosome 4. MpM1 is the first gene-based marker developed specifically for resistance to aflatoxin accumulation in maize and can now be integrated into existing marker assisted selection programs aimed at incorporating resistance into elite maize breeding lines.