Mapping quantitative trait loci associated with resistance to aflatoxin accumulation in maize inbred Mp719

Authors: Womack, Erika; Williams, William; Windham, Gary; XU, WENWEI - Texas A&M University

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2020
Publication Date: 2/4/2020
Citation: Womack, E.D., Williams, W.P., Windham, G.L., Xu, W. 2020. Mapping quantitative trait loci associated with resistance to aflatoxin accumulation in maize inbred Mp719. Frontiers in Microbiology. 11(11):1-8. https://doi.org/10.3389/fmicb.2020.00045.
DOI: https://doi.org/10.3389/fmicb.2020.00045

Interpretive Summary: Aspergillus flavus is a fungus that grows on corn. This fungus produces a toxin called aflatoxin that is very harmful to animals and humans that consume. In addition to health consequences, aflatoxin contamination of food and feed causes significant impacts to the economy due to yield loss and reduced value of the corn grain. Minimizing aflatoxin contamination in corn has been challenging. However, finding native resistance within the corn using chromosomal markers may help with this problem. In this study, we used many chromosomal markers called single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers to determine the location of chromosomal regions in corn that discourage the growth of the fungus and the accumulation of aflatoxin. Analysis identified two regions on the chromosome regions that may be very important to reduce aflatoxin accumulation in corn. These regions have been found in previous studies thus, confirming their influence in controlling aflatoxin resistance in corn.

Technical Abstract: Aflatoxins are carcinogenic and toxic compounds produced principally by fungal species Aspergillus flavus (Link:Fr) and A. parasiticus (Speare), which are common contaminants of food and feed. Aflatoxins can be found at detrimentally high concentrations and can readily contaminate pre-harvest maize (Zea mays L.) grain. Sources of resistance to aflatoxin accumulation in maize have been identified; however, the highly quantitative nature and complex inheritance of this trait have limited the transfer of aflatoxin accumulation resistance into agronomically desirable elite lines. Mapping of quantitative trait loci (QTL) and identification of closely linked molecular markers to the loci associated with resistance could be used in marker-assisted selection (MAS) and could effectively improve maize breeding programs. A bi-parental mapping population comprised of 241 F2:3 families derived from the cross of inbred lines Mp705 (susceptible) x Mp719 (resistant) was evaluated in replicated field trials in three environments for resistance to aflatoxin accumulation under artificial inoculation. The genetic linkage map was constructed with 1,276 single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) molecular markers covering a total genetic distance of 1,642 cM across all ten maize chromosomes. Multiple interval mapping revealed that majority of the aflatoxin-reducing alleles and the source for the larger effect QTL identified in this study were contributed from Mp719, the resistant parent. Two QTL identified on chromosome 1 (bin 1.06-1.07) and chromosome 3 (bin 3.09) were the most stable across different environments and when combined, explained 24.6% of the total phenotypic variance across all three environments. Results from the study showed that these chromosomal regions harbor important QTL for influencing aflatoxin accumulation, which is consistent with previous reports with other different mapping populations. These consistent QTL may be the most promising for controlling aflatoxin accumulation in maize grain and identifying beneficial alleles derived from Mp719 and closely linked molecular markers through QTL analysis for implementation of MAS could accelerate breeding efforts to reduce aflatoxin accumulation in maize.