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<OL><LI> Identify natural compounds highly effective as antifungal or antimycotoxigenic in almond orchards. <LI> Identify the most efficient molecular targets (e.g., mitochondrial superoxide dismutase (Mn-SOD) for newly discovered compounds using functional genomics approaches. <LI> Determine an effective method for delivery of newly discovered natural compounds, leading to a target-specific strategy for an easy, safe and economic approach to fungal pathogen control in the field or during processing and storage.
Approach: 1. Antifungal bioassays. A. flavus assays will be conducted potato dextrose agar (PDA) plates containing phenolic reagents and/or inhibitors of mitochondrial respiration and cell growth will be monitored after 5 to 7 days at 28 oC. Colony growth will be measured based on percent radial growth compared to control colonies Vincent equation. Volatile compound, antifungal activity will be monitored by the vapor-agar contact method. <P>2. Almonds. Undamaged almonds will be surface sterilized and re-hydrated in sterile water. Following re-hydration, one group of almonds will remain sterile and group will be with spores of A. flavus antifungal activities of test compounds will be monitored. <P>3. Yeast bioassays, Saccharomyces cerevisiae will be used in a high-throughput bioassay to identify molecular targets of effective compounds. Genetic groups to be monitored are those lacking genes for 1) signal transduction, 2) gene regulation, 3) antioxidation, 4)transporter or assembly proteins, and 5) DNA damage control/enzymes for energy metabolism. Yeast assays will include serially diluted cells from 10-fold to 105-fold in synthetic glucose medium. Cell growth will be monitored by a spectrophotometer.