Location: Corn Host Plant Resistance ResearchTitle: Development of a gene - based marker correlated to reduced aflatoxin accumulation in maize) Author
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2013
Publication Date: 7/16/2013
Citation: Mylroie, J.E., Warburton, M.L., Wilkinson, J.R. 2013. Development of a gene - based marker correlated to reduced aflatoxin accumulation in maize. Euphytica. 194:431-441. Interpretive Summary: Aflatoxins are carcinogenic and toxic metabolites produced by the fungus Aspergillus flavus during infection of corn and other seed oil crops. One of the most promising avenues to combat aflatoxin contamination is the development of corn with genetic resistance. Finding regions of the chromosome that contribute to resistance and then selecting directly at the level of the DNA, rather than evaluating plants for resistance to aflatoxin accumulation in field tests, may speed breeding progress for this trait. Genetic mapping may identify very large regions of the chromosome in which a gene for resistance is located, but other unwanted genes may also be found in the region if it is too large. Finding the sequence of only the gene of interest, and using it to develop easy to screen markers, should avoid that problem. In this study, one marker identified in a candidate gene for aflatoxin resistance was found to map to chromosome 4, and plants carrying the marker were found to be significantly more resistant to aflatoxin contamination than those plants not carrying the marker. Selection based on this molecular marker should accelerate development of corn hybrids with resistance to aflatoxin contamination.
Technical Abstract: 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 gene – based markers for resistance. Previous studies have identified candidate genes that were differentially expressed in response to A. flavus infection. One gene, a chloroplast precursor, was found to contain multiple polymorphisms, which were used to design a marker, designated MpM1, which differentiated between the “resistant” and “susceptible” forms of the allele. This marker was used to screen three populations of F2:3 mapping families and was found to map to chromosome four in these F2:3 populations. Additionally, MpM1 found to have a significant phenotypic effect for aflatoxin resistance. Furthermore, the marker MpM1 identified a previously unknown QTL 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.