Postharvest Control of Alternaria alternata in Table Grapes Using a Tetraclinis articulata Essential Oil Nanoemulsion: Antifungal Activity and Molecular Docking Insights.

Alternaria alternata infects grapes postharvest and causes harmful fruit rot. This study evaluated Tetraclinis articulata essential oil (TA-EO) nanoemulsion as a sustainable biocontrol strategy for Vitis vinifera cv. Red Globe. After storage, grapes were inoculated with A. alternata and treated with TA-EO nanoemulsions at different concentrations. Disease severity index (DSI), total polyphenol, flavonoid contents, and antioxidant activity were evaluated after 3, 6, 9, and 12 days. The EO, rich in α-pinene, camphor, and limonene, was successfully encapsulated into a stable nanoemulsion (358-392 nm; -40 mV). In vitro, nanoemulsion showed a minimum inhibitory concentration (MIC) of 500 µg/mL and a selectivity index (SI) of 1. In vivo, treatment at 2 g/L reduced DSI to 9.9% after 12 days versus 69.5% in the untreated control, comparable to a commercial fungicide (10.2%). Treated grapes maintained higher polyphenol (20.20 mg GAE/g DW) and flavonoid contents (48.83 mg QE/g DW), with stronger antioxidant activity (IC50 = 284.73 µg/mL; molecular docking, revealing strong interactions of α-terpineol and terpinen-4-ol with A. alternata thioredoxin reductase and membrane transporters. This method extended 12 days shelf-life grapes by comparison to the control group. This approach represents an eco-safe strategy EC50 = 182.10 µg/mL) than infected controls for sustainable viticulture.