Genes Contributing to Aflatoxin Accumulation Resistance in Maize.

Maize (Zea mays L.) is a crop of global importance, but is prone to infection by Aspergillus flavus and to contamination by the deadly aflatoxins this fungus produces. The identification of genes contributing to resistance and the development of resistant germplasm would aid in the reduction of the problem with minimal farmer intervention.  This study identified SNP markers associated with aflatoxin resistance in a panel of 287 maize inbred lines genotyped by sequencing and phenotyped for aflatoxin levels in replicated field trials of inoculated maize.  Results of this genome wide association analysis uncovered 117 SNPs associated with aflatoxin accumulation in one or more environments at p < 9.78 x 10^-6.  Ten SNP-trait associations exceeded a false discovery rate set at less than 10% (p < 3.83 x 10^-7).  Associated polymorphisms were validated in up to four QTL mapping populations developed and phenotyped for mapping aflatoxin resistance.  Together, the characterized association mapping panel and four QTL populations comprise a pipeline in which any candidate sequence can be tested for phenotypic effect on aflatoxin accumulation resistance.  SNP or InDel assays were developed for many genes identified by GWAS or from previous studies, and have been tested in the pipeline.  Genes with positive association or linkage to resistance are presented here, along with available genomic data including gene annotation, expression analysis, and sequence homology to known genes. Markers from within these gene sequences are being used to create near isogenic lines for each gene linked or associated with resistance.