Antifungal activity of diacetyl, a volatile organic compound, on Trichoderma lixii F2 isolated from postharvest Lanzhou lily bulbs

The most severe fungal disease is postharvest gray mold, which might cause massive losses in Lanzhou lily bulbs. Some microorganism-produced volatile organic compounds (VOCs) have been proven to have antifungal action and can be employed as fruit and vegetable preservation. Our most recent research discovered that diacetyl (2, 3-butanedione) produced by Bacillus subtilis CL2 could significantly prevent some pathogens. The goal of this investigation was to see if diacetyl had antifungal properties against Trichoderma lixii F2, one of the most common postharvest rot pathogens of Lanzhou lily bulbs. The results indicated that diacetyl (1.587 μL/mL) fumigation treatment significantly inhibited the hyphal growth, modified hyphal morphology, and disrupted the cell membrane integrity. In vivo tests the antifungal mechanisms of diacetyl on T. lixii F2 were performed in Lanzhou lily bulbs. The results indicated that the content of total phenols and flavonoids increased, while malondialdehyde decreased under different treatment by diacetyl. Meanwhile, the activities of peroxidase, polyphenol oxidase, catalase, and superoxide dismutase and phenylalanine ammonia-lyase in Lanzhou lily bulbs were investigated. It was showed that diacetyl could eliminate excessive reactive oxygen species, reduce the damage of plant cells, and improve the resistance of Lanzhou lily bulbs against T. lixii F2. This research reveals that diacetyl could activate antioxidant enzymes and disease-resistant enzymes in Lanzhou lily bulbs to prevent pathogenic fungus from invading and inducing resistance, laying the groundwork for future uses in preserving Lanzhou lily bulbs.