Potential of fumigation of orange fruits with volatile organic compounds produced by Saccharomyces cerevisiae to control citrus black spot disease at postharvest

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Volatile organic compounds (VOCs) from microbial origin are relevant in biological interactions and are considered promising environmentally safer fumigant agents to control postharvest diseases of fruits. The antagonist yeast Saccharomyces cerevisiae produces VOCs able to inhibit the development of plant pathogens, including the filamentous fungus Phyllosticta citricarpa, causal agent of citrus black spot. Thus, it was evaluated the effectiveness of VOCs produced by S. cerevisiae to control P. citricarpa in orange fruits stored in sealed glass containers. The exposure of P. citricarpa growing on potato-dextrose-agar to the synthetic mixture of VOCs, originally identified from S. cerevisiae, affected negatively the phytopathogen. Individually, 3-methyl-1-butanol and 2-methyl-1-butanol were the most effective VOCs inhibiting completely the mycelial growth and the germination and appressorium formation by conidia. Seven-day fumigation of orange fruits carrying quiescent infections of P. citricarpa, employing the VOC-producing S. cerevisiae or 3-methyl-1-butanol at 0.33μlml−1 of air space, controlled the development of new lesions close to 90%, even after removing the fruits from the VOC influence. Therefore, the biological fumigation of citrus fruits with S. cerevisiae or the use of formulations based on their VOCs are promising ecofriendly approaches to control citrus black spot during storage and shipment.