Ozone treatment controlled postharvest table grape blue mold by targeting cell membrane to cause membrane integrity disruption and inhibited the development of Talaromyces rugulosus and accumulation of ochratoxin A

Talaromyces rugulosus is a prevalent and devastating fungus responsible for table grapes blue mold and is capable of metabolizing ochratoxin A (OTA), which leads to substantial economic losses and poses potential health risks to human. This study investigates the effects of ozone fumigation on controlling postharvest blue mold caused by T. rugulosus, as well as the potential mechanisms of action. The results demonstrated that ozone treatment (2.0 mg L⁻¹) inhibited the expansion of blue mold caused by T. rugulosus in both ‘Sunshine Rose’ and ‘Red Globe’ grape varieties. In vitro experiments showed that ozone suppressed mycelial growth and spore germination by altering the ultrastructural morphology of both spores and hyphae. In addition, ozone treatment led to a significant improvement in reactive oxygen species (ROS) levels that increased malondialdehyde (MDA) content, electrical conductivity and caused leakage of proteins and nucleic acids, ultimately, deeply damaging cell membrane integrity. Molecular docking experiments indicated that ozone interacted with key proteins, ERG6 and ERG27, involved in ergosterol synthesis on the cell membrane, forming intermolecular hydrogen bonds. This interaction downregulated the relative expression of TrERG6 and TrERG27, thereby inhibiting ergosterol synthesis and reducing ergosterol content. Furthermore, ozone also reduced OTA accumulation by down-regulating the relative expression of crucial genes involved in OTA biosynthesis, including polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS), cytochrome P450 (P450), and ethanol dehydrogenase (ADH). Finally, ozone decreased weight loss, delayed the decline in the total soluble solids, vitamin C content, titratable acid and reducing sugars, which maintained the nutritional and edible quality of the grapes.