Breeding for resistance to aflatoxin accumulation in maize

Contamination of maize,Zea mays, grain with aflatoxin, a naturally occurring toxin produced byAspergillus flavus, frequently reduces the value and marketability of maize produced in the southern USA. Drought, high temperatures, and insect damage are often associated with high levels of maize aflatoxin contamination. Growing resistant maize hybrids is generally considered the most feasible method of reducing or eliminatingA. flavus infection and subsequent accumulation of aflatoxin. Developing appropriate screening techniques and identifying maize germplasm with resistance to aflatoxin contamination provides the foundation for a breeding program. Only a few sources of aflatoxin resistance have been identified. Four germplasm lines (Mp313E, Mp420, Mp715, and Mp717) have been developed and released by USDA-ARS at Mississippi State University. NC 388, developed at North Carolina State University, is reported as another putative source of aflatoxin resistance. Conventional phenotypic selection was used to successfully combine resistance to aflatoxin contamination from two of these lines, Mp313E and Mp715, with desirable agronomic qualities from Va35. The identification of quantitative trait loci (QTL) associated with resistance to aflatoxin contamination will also permit the use of marker assisted selection in transferring resistance into elite germplasm lines. Development of parental inbreds that combine aflatoxin resistance with superior agronomic quality is an essential component of a hybrid maize breeding program designed to reduce or eliminate aflatoxin contamination.