UV-C treatment elicits resistant responses against Botrytis cinerea infection and the improvement of fruit characteristics in grapevines

UV-C exhibits efficient growth inhibition against a wide range of microorganisms and has an elicitor impact on the induction of resistance against pathogens in host plants, emerging as a promising alternative to fungicides. This study examined the defense elicitor effect of both low (0.05 W/cm²) and high (0.133 W/cm²) powered UV-C (275 nm) against Botrytis cinerea on grapevines. Gene expression, total stilbene content, and the quality of the berries were assessed in ‘Kyoho’ grapevines irradiated with UV-C. Low and high-powered UV-C reduced the in vitro growth of B. cinerea by 40–50% and lowered the in vivo infection and disease severity by 40–85% in the leaves. Lesion formation was reduced by 20–50% in berries treated with UV-C. The spores of B. cinerea did not infect the unwounded berries of ‘Shine Muscat’ and ‘Kyoho’ grape treated with UV-C. The augmented levels of total soluble solids, color values, and reduced titratable acidity improved the quality of the UV-C-irradiated ‘Kyoho’ berries compared to the control. The total stilbene content was four to five times higher with 37.48 µg ­g⁻¹ fresh weight (FW) using low UV-powered UV-C and 43.11 µg ­g⁻¹ FW using high UV-powered UV-C in ‘Kyoho’ berry skins treated with UV-C compared to the control (9.24 µg ­g⁻¹ FW), with predominant levels of trans-resveratrol. The genes involved in stilbene synthesis, defense, and antioxidant activity were strongly upregulated in the leaves and berries of grapevines in response to the low and high UV-C treatments. The low and high UV-C treatments elicit the induction of resistances in grapes against B. cinerea and improve the quality of berries. Future research will be needed on other parameters before UV-C irradiation can be applied to inhibit the incidence of grey mold in vineyards.