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United States Department of Agriculture

Agricultural Research Service

Title: A Micro Bioassay for Fungicide Discovery

Authors
item Wedge, David
item Kuhajek, J - UNIV OF MS

Submitted to: Southern Association of Agricultural Scientists Bulletin Biochem. Biotech.
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 1998
Publication Date: N/A

Interpretive Summary: Faster, less expensive microbioassays are needed to test natural products for fungicidal activity. A rapid, high-throughput microbioassay for testing natural products for fungicide activity against Botrytis, Colletotrichum, Fusarium, and Discula was developed. This bioassay is accurate and sensitive enough for comparison of dose-response relationships of natural and synthetic fungicides. The bioassay will be useful in dicovery of natural product-based fungicides.

Technical Abstract: The continuing development of antimicrobial resistance in plant and human pathogens necessitates the discovery and development of new fungicides. At the newly opened National Center for the Development of Natural Products (NCDNP) a unique relationship exists between the University of Mississippi and US Department of Agriculture, Agricultural Research Service. The mission of the NCDNP is to discover, develop, and commercialize useful agrochemical and pharmaceutical natural products. Our current research focuses on developing microbioassay testing protocols suitable for discovery of natural product fungicidal agents to control important plant pathogenic fungi. A 96-well microtiter plate bioassay using conidia from Botrytis, Colletotrichum, Fusarium, and Discula was developed to evaluate growth effects of common phytochemical extraction solvents and fungicides. Absorbance (620nm) measured at 24, 48, 72, and 96 hours indicated that acetone, hexane, methanol, methylene chloride, and 95% ethanol at concentrations up to 4% had no inhibitory effect on growth of the tested fungi. Fungal growth measurements show that 48 hours is the optimum time to evaluate growth relationships. The microtiter bioassay tested is an accurate, sensitive, and rapid detection system that should differentiate dose-response relationships and differences in fungal sensitivity to known fungicides. Ultimately, the development of plant-derived crop protectants and alternative agricultural applications as phytopharmaceuticals is sought.

Last Modified: 12/22/2014
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