Benzothiadiazole Enhances Resveratrol and Anthocyanin Biosynthesis in Grapevine, Meanwhile Improving Resistance to Botrytis cinerea

Pre-harvest multiple treatments of grapevine (cv. Merlot) with the plant activator benzothiadiazole (BTH, 0.3 mM) enhanced trans-resveratrol content in berries by about 40%. An even more striking effect was observed on anthocyanin synthesis, particularly on malvidine 3-glucoside, malvidine 3-(6-O-acetyl)glucoside and malvidine 3-(6-O-p-coumaroyl)glucoside, whose amounts were more than doubled. These data were obtained with a novel and time-saving HPLC method, set up for the simultaneous detection of stilbenes and anthocyanins, using an RF-10Axl fluorimetric detector instrument, with excitation at 330 nm and emission at 374 nm, and a SPD-Avp UV detector with absorption at 520 nm. Furthermore, BTH treatments induced systemic acquired resistance in grapevine, as assessed by inoculating clusters from treated and untreated plants with Botrytis cinerea. Disease severity, estimated according to the percentage of infected berries per cluster, was significantly reduced in grapes from BTH-treated plants. These results indicate that BTH treatments, besides improving the content of two important classes of nutraceuticals, with their well-known antioxidant, antitumoral, and phytoestrogenic activities, could be exploited in vineyard to protect grape against gray mould infection, thereby limiting an excessive use of fungicides Keywords: Anthocyanins; resveratrol; BTH; HPLC; Botrytis cinerea; Vitis vinifera; nutraceuticals; systemic acquired resistance; phytoalexins.