Reducing Aflatoxin Contamination Using Biological Control and Crop Management

1. Advance biocontrol technologies through strain selection, formulation, and adaptation to agronomic practices. Influences of agronomic practices on long-term effects of atoxigenic strain treatments will be determined. Improved criteria for selection of atoxigenic strains and strain mixtures will be sought and a collection of atoxigenics of potential value in target regions developed. Inexpensive substrates and formulations for atoxigenic product will be evaluated. Atoxigenic strain technology will be further adapted to aflatoxin management in commercial maize and tree crops. 2. Characterize adaptive differences among Vegetative Compatibility Groups (VCGs) and strains of Aspergillus flavus including adaptation to host, environment, and ecosystem. Adaptations of A. flavus to life-strategy, host, and environment will be characterized and variability within and between VCGs assessed. It will be determined if cotton and maize differentially influence the composition of A. flavus communities and if VCG composition is location dependent. 3. Use advanced molecular tools to characterize genetic basis for adaptive divergence among aflatoxin-producing and closely related fungi and to develop SNP databases and practical methods for monitoring temporal shifts in compositions of A. flavus communities. Quantitative Pyrosequencing assays will be developed that distinguish specific fungi or groups of fungi in field and laboratory samples. Relationships among morphotypes and vegetative compatibility groups will be clarified while molecular methods for identification are developed. Genome-wide comparisons will be used to identify both adaptive features and paths to adaptation among VCGs successful on different hosts. 4. Identify agronomic, environmental, and ecological factors (e.g. hosts) that favor development of highly toxic fungal community structures and practices that favor selection and retention of atoxigenics. Factors that favor dominance and dispersal of the S strain of A. flavus and that result in loss of A. flavus with reduced aflatoxin-producing potential will be determined in areas with severe levels of contamination attributable to the S strain. This will be done by examining relationships between climatic, biological, ecological, and geographical factors and the spatial and temporal distribution of Aspergillus section Flavi.