Benzothiadiazole-Induced Lipoxygenase Pathway Activation Enhances Chardonnay Grape ( Vitis vinifera L.) Resistance to Botrytis cinerea

Pre harvest spraying of benzothiadiazole (BTH) induces grape disease resistance and regulates the quality of wine grapes. This study investigated the mechanism of spraying 50 mg/L BTH during the pea-size stage to regulate the metabolic pathway of grape lipoxygenase (LOX). The results indicated that BTH up-regulated the expression of VvFAD21, facilitating the conversion of saturated fatty acids into unsaturated fatty acids. Additionally, BTH treatment enhanced the expression levels of VvLOXA, VvLOXB, VvLOXC, VvHPL1, VvHPL2, VvADH1, and VvADH2, resulting in increased production of C₆/C₉ aldehydes and alcohols. Antibacterial assays of LOX metabolites demonstrated that 40-160 μg/mL of hexanal and E-2-hexenal significantly inhibited Botrytis cinerea, the causal agent of grape gray mold. This study clarifies the mechanisms by which BTH regulates LOX metabolism to enhance grape health and berry quality, providing a theoretical basis for its application in improving grape disease resistance and controlling berry quality.