Location: Food and Feed Safety Research
Project Number: 6054-41420-009-000-D
Project Type: In-House Appropriated
Start Date: Apr 19, 2021
End Date: Apr 18, 2026
Objective 1: Identify key genes and metabolites involved in fungal growth, toxin production and virulence during the Aspergillus flavus-corn interaction that can be used as targets for intervention strategies. Subobjective 1.A: Identify secondary metabolites produced by Aspergillus flavus during interaction with corn and characterize their structure, biosynthesis and contribution to the fungus’ ability to survive, colonize the crop and produce toxins. Subobjective 1.B: Identify key genes and gene networks using transcriptomic analysis of Aspergillus flavus and Aspergillus flavus-crop interaction that are involved in fungal growth, development, toxin production and virulence. Objective 2: In situ and in planta analysis of the impact of environmental stresses associated with predicted climate change on Aspergillus flavus biology and biocontrol. Subobjective 2.A: Analysis and functional characterization of genes differentially expressed in situ under altered environmental conditions. Subobjective 2.B: In planta assessment of fungal virulence and aflatoxin production. Objective 3: Identify volatile organic compounds (VOCs) and extrolites produced by non-aflatoxigenic Aspergillus flavus strains that reduce growth and/or toxin production in aflatoxigenic aspergilli and characterize their mechanism of action.
Aflatoxin contamination in crops such as corn, cottonseed, peanut, and tree nuts caused by Aspergillus flavus is a worldwide food safety problem. Aflatoxins are potent carcinogens and cause enormous economic losses from reduced value of contaminated crops. Biosynthesis of these toxins has been extensively studied, but much remains to be determined regarding how gene regulatory networks respond to the complex nutritional and environmental cues perceived by the fungus during colonization of the host crop. While transcriptomics has provided some insights into genes and gene networks that govern A. flavus development and aflatoxin production, very little is known about the role that fungal metabolites play in the infection process or during interactions with competing microbes in the field or on the crop. To address these knowledge gaps, we will use transcriptomics, metabolomics and bioassay to identify and functionally characterize fungal genes, gene networks and metabolites that are critical for fungal host colonization and aflatoxin production during interaction of A. flavus with corn. These analytical techniques will also be used to define how physiological stress (i.e. changing environmental conditions) affects fungal virulence and survival and how introduced non-aflatoxigenic A. flavus strains prevent native, aflatoxigenic strains from contaminating crops thus increasing the effectiveness of A. flavus biological control. We expect to utilize the fundamental knowledge gained from the proposed studies for the development, validation and implementation of targeted strategies (biological control and host-resistance) to significantly reduce pre-harvest aflatoxin contamination of crops intended for consumption by humans or animals.