Ozone treatment of postharvest apricot fruit reveals a pathway to enhanced black spot disease resistance mediated by DNA methylation.

Postharvest apricot fruits are highly susceptible to Alternaria alternata infection, which induces black spot disease and causes considerable economic losses. This study investigated the effect of ozone (O₃) on the resistance of 'Chuanzhihong' apricots to A. alternata using integrated metabolomic, transcriptomic, and whole-genome methylomic analyses. Fruits were inoculated with A. alternata, treated with 46 μL·L-1 O₃ for 10 min, and stored for 6 days. O₃ significantly inhibited disease progression, promoted the accumulation of 11 amino acids, elevated jasmonic acid (JA) and salicylic acid (SA) contents, and activated relevant metabolic pathways. It regulated JA/SA biosynthesis genes (LOX2S, ACX, ACAA1) and the key signal transduction transcription factor MYC2. Dynamic CG/CHG/CHH hypermethylation and hypomethylation triggered by O₃ modulated the transcription of 29 pivotal defense-related genes. Collectively, O₃ enhances postharvest disease resistance in apricots by orchestrating DNA methylation, phytohormone crosstalk, and amino acid metabolic networks.