ARS | Publication request: Ear Rot, Aflatoxin Accumulation, and Fungal Biomass in Maize after Inoculation with Aspergillus flavus

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2010
Publication Date: January 1, 2011
Citation: Williams, W.P., Ozkan, S., Ankala, A., Windham, G.L. 2011. Ear rot, aflatoxin accumulation, and fungal biomass in maize after inoculation with Aspergillus flavus. Field Crops Research. 120:196-200.

Interpretive Summary: Aflatoxin, a toxin produced by the fungus Aspergillus flavus occurs naturally in corn. Aflatoxin is a potent human carcinogen and is toxic to livestock, pets, and wildlife. When contaminated with aflatoxin, the value of corn grain is markedly reduced. Eight germplasm lines with different levels of resistance to aflatoxin accumulation were crossed in all possible combinations. The resulting hybrids were evaluated for visible ear rot and aflatoxin accumulation and A. flavus infection in the grain. A. flavus infection was determined by quantitative real-time polymerase chain reaction (qRT-PCR) assays. Three of the germplasm lines included as parents of the crosses (Mp313E, Mp715, and Mp717) were developed and released as sources of resistance to aflatoxin accumulation in the grain. Hybrids produced from these lines exhibited both reduced levels of aflatoxin contamination and reduced fungal infection. Conversely, one line, GA209, exhibited reduced A. flavus infection and ear rot, but high levels of aflatoxin accumulation. Mp313E, Mp715, and Mp717 should be useful in breeding programs targeting both reduced levels of fungal infection and aflatoxin accumulation. Selection for lower fungal infection alone would not necessarily be effective in reducing aflatoxin accumulation.

Technical Abstract: Aflatoxin, a toxin produced by the fungus Aspergillus flavus Link:Fries, occurs naturally in maize (Zea mays L.). Aflatoxin is a potent human carcinogen and is toxic to livestock, pets, and wildlife. When contaminated with aflatoxin, the value of maize grain is markedly reduced. Eight germplasm lines representing different levels of resistance to aflatoxin accumulation were used as parents of a diallel cross. The cross was evaluated for visible ear rot and aflatoxin accumulation and A. flavus infection in the grain. A. flavus infection was determined by quantitative real-time polymerase chain reaction (qRT-PCR) assays. Estimates of general combining ability (GCA) effects were highly significant for both reduced A. flavus infection and reduced aflatoxin accumulation for Mp313E, Mp715, and Mp717. Conversely, GCA effects associated with GA209 were significant for reduced A. flavus infection and ear rot, but high levels of aflatoxin accumulation. Mp313E, Mp715, and Mp717 should be useful in breeding programs targeting both reduced levels of fungal infection and aflatoxin accumulation.