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

ABSTRACT

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 (IC ₅₀ = 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 EC ₅₀ = 182.10 µg/mL) than infected controls for sustainable viticulture.