Identification of quantitative trait loci contributing resistance to aflatoxin accumulation in maize inbred Mp715

摘要

Aflatoxin is a mycotoxin produced by the fungus Aspergillus flavus (Link:Fr), an opportunistic ear-rot pathogen of maize (Zea mays L. ssp. mays). Pre-harvest contamination of maize grain with aflatoxin is a chronic problem worldwide and particularly in the Southeastern US. Quantitative trait loci (QTL) were mapped by multiple interval mapping (MIM) in a population consisting of 250 F-2:3 lines derived from the cross Mp715 x Va35. Mp715 is resistant to the accumulation of aflatoxin and Va35 is susceptible. The population was genotyped with 1200 single-nucleotide polymorphism (SNP) and simple sequence repeat (SSR) molecular markers and phenotyped for the accumulation of total aflatoxins under artificial inoculation in four environments. Both parents contributed resistance alleles. Two QTL in bins 6.06 and 7.03 were the most promising for the marker-assisted introgression of the resistance present in Mp715. They were the most consistent across individual environments and together were responsible for nearly 30% of the phenotypic variance when data was combined across all four environments. In addition to those two QTL, Mp715 was also the source of the beneficial aflatoxin-reducing allele for several smaller effect QTL. Once their effect is validated in further experiments, the identification of these relatively large effect QTL should facilitate the utilization of this aflatoxin accumulation-resistant germplasm in applied maize breeding programs.