Objective 1: Identify key genes regulating virulence and toxin production in Penicillium species, the causal agents of blue mold, to develop novel gene or protein targets for control in commercially stored pome fruit. Sub-objective 1.A: Identify new Penicillium spp. virulence and toxin biosynthetic genes via comparative genomics and transcriptomics. Sub-objective 1.B: Characterize fungal virulence and toxin genes in Penicillium spp. using a targeted gene deletion approach. Objective 2: Integrate genomic-based strategies and evaluate novel tools to manage postharvest blue mold decay in commercial storage caused by Penicillium species on pome fruit. Sub-objective 2.A: Determine difenoconazole baseline sensitivity and characterize resistant blue mold isolates. Sub-objective 2.B: Identify Penicillium spp. genes associated with difenoconazole resistance and develop a molecular-based detection system.
Multiple approaches are outlined in this project that encompass both basic and applied methodologies to maintain pome fruit quality, deliver effective strategies to manage blue mold decay, and eliminate mycotoxins from processed pome fruit products. Comparative genomics and transcriptome sequencing will be used to discover new fungal virulence genes and pathways that regulate Penicillium spp. virulence, and toxin production to develop pathogen-specific management strategies. Additionally, mechanisms of postharvest fungicide resistance in Penicillium spp. will be determined using a genomics approach to develop molecular-based management tools for producers. Our applied research focus will utilize standard microbiological methods to determine baseline sensitivity to a new postharvest fungicide currently used to manage blue mold decay and will help producers monitor future shifts in sensitivity indicative of resistance. Characterization of fungicide-resistant isolates will provide practical information on the viability and persistence of such isolates in the packing and storage environments and their impact on control using currently available chemical tools labeled for pome fruits. Results from the current study will also guide growers in making decisions for use of the most efficacious fungicides to control blue mold.