Efficacy of Wickerhamomyces anomalus in the biocontrol of black spot decay in tomatoes and investigation of the mechanisms involved

Black spot caused by Alternaria alternata is a common postharvest disease of tomato. In the current study, Wickerhamomyces anomalus was used to control the disease. The experimental results showed that W. anomalus had the effect of controlling black spot disease, and 108 cells/mL of W. anomalus was the most suitable concentration for controlling the disease. W. anomalus has the ability to reduce the spore germination and inhibit germ tubes growth of A. alternata, and its volatile substances also have inhibitory effects on pathogenic fungi. W. anomalus can reduce the natural decay rate of tomato, retain postharvet quality of tomato, and increase the contents of ascorbic acid and lycopene. In addition, W. anomalus can significantly reduce the H2O2, O2– production rate, and MDA contents of tomato. It increased the enzymatic activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione S-transferase (GST), and increased the content of glutathione (GSH). Furthermore, the yeast improved the ability of tomato to resist oxidative stress, thereby better resisting the pathogen infection. Generally, this study will significantly contribute to use antagonistic yeasts or their products to control postharvest diseases of horticultural produces.