Confirmation of QTL Reducing Aflatoxin in Maize Testcrosses

Aflatoxins, produced by the fungus Aspergillus flavus Link:Fr, constrain maize (Zea mays) production in some regions. Difficulties in breeding resistance to this toxin make it a good target for quantitative trait locus (QTL) identification and molecular-assisted breeding. Multiple QTL have been identified for aflatoxin resistance in inbred lines per se; however, it has not been determined if aflatoxin resistance QTL would be useful in hybrids or have deleterious pleiotropic effects. The objectives were to confirm the presence, in testcrosses, of QTL estimates previously identified in lines per se; estimate new QTL for reducing aflatoxin accumulations and agronomic traits in hybrids; and evaluate co-localization of QTL that suggest pleiotropic effects with measured traits. Plant height, flowering time, starch, oil, and protein were also included in the analysis. Significant environment and genetic x environment interaction were detected for most traits. Heritability estimates were equivalent to those previously reported, and no meaningful correlations were detected between aflatoxin accumulation and other traits. Ninety-three QTL were detected across 14 traits measured in five environments. Aflatoxin-reducing QTL detected in per se analyses were detected in testcrosses on chromosome 1, with new QTL detected on chromosomes 3, 4, 8, and 9. Co-localization of aflatoxin-reducing QTL detected on chromosome 9 with QTL for silking date suggests a pleiotropic effect based on avoidance or agronomics and not a resistance QTL.