Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2007
Publication Date: 2/25/2008
Citation: Das, M.K., Ehrlich, K., Cotty, P.J. 2008. Use of Pyrosequencing to Quantify Incidence of a Specific Aspergillus flavus Strain Within Complex Fungal Communities Associated with Commercial Cotton Crops. Phytopathology. 98:282-288. Interpretive Summary: Aflatoxins are highly toxic cancer causing poisons that are produced by certain fungi. The quantity of these poisons in the environment and in foods can be reduced by competitively excluding aflatoxin producers with non-aflatoxin producing biological control strains. The use of competitive exclusion to reduce contamination has been under development for over a decade. Development is limited by the time consuming and expensive methods that must be applied to analyze the extent of competitive exclusion that occurs. The current work developed a rapid and relatively inexpensive method for determining the extent of competitive exclusion by analyzing DNA isolated from the environment. This method is a promising tool for greatly speeding up the development and expansion of competitive exclusion for the prevention of aflatoxin contamination.
Technical Abstract: Aflatoxins are highly toxic carcinogens produced by several species of Aspergillus, and its presence in foods causes chronic health effects including immune-system suppression, growth retardation, cancer, and death in both humans and domestic animals. Atoxigenic strains of Aspergillus flavus have been used as aflatoxin management tools on over 50,000 hectares of commercial crops since 2000. To assess treatment efficacy, atoxigenic strain incidence is routinely monitored by vegetative compatibility analyses that require culturing, generation of auxotrophs, and complementation with tester mutants. Two pyrosequencing assays that require no culturing were developed for monitoring incidences of atoxigenic strains on ginned cottonseed based on characteristic Single Nucleotide Polymorphisms (SNPs) in the aflR and pksA genes. Results indicate that pyrosequencing possesses the potential to becoming a powerful tool for monitoring atoxigenic strains within complex A. flavus communities without the limitations imposed by traditional culturing methods.