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The overall objective of this project is to understand the biological and ecological significance of aflatoxin production in the fungus Aspergillus flavus. The specific objectives are to test the following four hypotheses:--Hypothesis 1: The effects of aflatoxin production on the fitness of A. flavus vary as a function of environmental conditions, particularly environmental stress;--Hypothesis 2: Aflatoxin production affects fitness differently in saprotrophic vs. pathogenic phases of the A. flavus life cycle;--Hypothesis 3: Aflatoxin increases the survival of A. flavus dormant structures by protecting them against soil microorganisms;--Hypothesis 4: Aflatoxin production increases the fitness of A. flavus when competing with insects for resources.
Aflatoxin is a highly carcinogenic compound produced by fungi that is major contaminant of food supplies worldwide. This project aims to understand the regulation of aflatoxin production and the role of aflatoxin in the ecology of the fungi that produce it. The current bias in agriculture is to view fungal toxins in terms of their toxigenicity to humans and livestock. However, the perspective in this project is that these toxins evolved to benefit the fungi that produce them, not to be toxic to humans. The effects of aflatoxin on fungal ecology are largely unknown. If we could understand how these toxins affect the biology and ecology of the most important fungus that produces aflatoxin, Aspergillus flavus, we have a greater potential for combating toxin-producing molds before they contaminate food supplies with aflatoxin. For example, biological control of A. flavus using strains of the same fungus that do not produce aflatoxin is a potential strategy for combating aflatoxin contamination. We will determine how aflatoxin affects the growth and survival of these fungi under a variety of environmental conditions to determine how aflatoxin benefits the fungus. Therefore, the results of this project may help in designing and implementing optimal biocontrol strategies based on maximizing the fitness of nontoxigenic strains. These studies will provide insights into the ecology of this fungus and may contribute to more rational ways of reducing aflatoxin contamination.