Aflatoxin accumulation in a maize diallel cross containing inbred lines with expired plant variety protection

Abstract

In-field infection of maize (Zea mays L.) ears by the fungus Aspergillus flavus Link:Fr causes pre-harvest aflatoxin contamination of maize grain. Germplasm lines with host-plant resistance to aflatoxin accumulation are available to breeders, but these lines often possess undesirable agronomic characteristics. Commercial lines with expired plant variety protection (ex-PVP lines) are a potential source of elite germplasm available to public maize breeders. A diallel cross containing three aflatoxin-accumulation-resistant germplasm lines and seven ex-PVP lines were evaluated in replicated trials for aflatoxin contamination after artificial inoculation and for yield. The resistant germplasm lines Mp313E, Mp715, and Mp717 were the only lines with significant general combining ability (GCA) for reduced aflatoxin accumulation. Of the ex-PVP lines evaluated, the Stiff-Stalk line F118 was the most promising line to use in breeding crosses. Based on its GCA, it was the only ex-PVP line that did not significantly increase aflatoxin and the only ex-PVP line that significantly increased yield. Second-cycle breeding lines derived from crosses between F118 and the resistant donor lines will be valuable if they combine the donor lines’ disease resistance with F118’s earlier maturity while introgressing the disease resistance into a genetic background that aligns with the industry’s well-defined heterotic groups.