Mapping Aflatoxin Accumulation Resistance Factors in Maize

Aflatoxin, produced by the fungus Aspergillus flavus, is a serious economic and health threat worldwide.  Resistance to aflatoxin accumulation and ear rot caused by A. flavus in maize has been studied using QTL and association mapping. Several QTL for resistance have been identified from various resistance sources, and a meta-analysis and ongoing Near Isogenic Line testing confirms that some QTL are stable and useful for increasing resistance in various genetic backgrounds. Genome-wide association mapping has been conducted on an association mapping panel created with diverse susceptible and resistant maize inbred lines crossed onto a common tester and phenotyped in 8 environments.  In the current study, GWAS was done with 261,184 SNPs (MAF > 5%) identified via Genotype By Sequencing, and 119 SNPs representing 87 genes were associated with aflatoxin levels in grain (P ≤ 9.78 x 10^-6). The use of linkage disequilibrium values for this dataset is being used to determine the genes causing the association. An automated pipeline to use the associated SNPs and their gene effect calculated from the GWAS study in an analysis of annotated maize pathways is being performed to help identify genetic resistance mechanisms.