Molecular Omics Unveils the Antimicrobial Mechanism of UV-LED-Induced Chitosan Composite Film Against Penicillium italicum.

Penicillium italicum is the predominant postharvest pathogen of citrus fruits, causing substantial economic losses. UV-LED light-activated chitosan/TiO2/Ag (CTS/TiO2/Ag) composite membrane solution is a novel and efficient antifungal strategy, yet its molecular mechanism remains unclear. This study employed integrated transcriptomic and metabolomic analyses to elucidate its inhibitory mechanism against P. italicum. Transcriptomic analysis identified 3120, 2601, 2543, 161, and 171 differentially expressed genes across time points, with numbers increasing over time; UV combined with red LED showed the strongest effect. Enriched pathways were primarily associated with carbohydrate, lipid, and amino acid metabolism, indicating disruption of core cellular functions. Metabolomic analysis revealed that ABC transporter synthesis was most affected; betaine downregulation suggested impaired efflux and reduced viability. Decreased glucose-6-phosphate disrupted glycolysis and the TCA cycle, likely inducing autophagy, while reduced ornithine indicated amino acid metabolic dysfunction, inhibiting protein synthesis, cell proliferation, and signal transduction. These findings demonstrate that UV-LED-activated CTS/TiO2/Ag composite membrane solution likely compromises cell wall integrity, suppresses ribosome biogenesis, triggers autophagy, and inhibits mycelial growth of P. italicum, providing a theoretical basis for novel fruit preservation technologies.