How abiotic stress induced by artificial wounding changes maturity levels and berry composition of Merlot (Vitis vinifera L.)

Phenolic compounds are crucial for grape berry quality, wine, and human health. The factors that dramatically affect the composition and levels of metabolites are biotic and abiotic plant stressors. Wounding is one of these stressors. However, little is known about its effect on the accumulation and biosynthesis of the whole phenolic profile. This study examined the effects of artificial leaf wounding on metabolite accumulation in 'Merlot' grapes. Twenty-year-old vines underwent ten wounding treatments at different times. Results showed diverse responses with practical implications for managing berry maturity and quality. Early-season treatments accelerated ripening, while late-season treatments halted sugar accumulation. Late treatments increased total phenolics, but responses varied in the phenolic profile. T5 had the highest total phenolics, while T1 exhibited the highest tannin content. Wounding treatments increased total anthocyanins compared to control. Flavonoids and hydroxybenzoic acids responded differently, with T9 showing the highest ( +)-Catechin and Syringic acid contents. Vanillic acid T6 had the highest (-)-Epicatechin control content. Except for T7, all treatments had higher trans-resveratrol levels than control. Injury direction and timing had numerical and content effects, although not statistically significant. 'Merlot' grapes can perceive artificial wounds and mount a robust defense response. Wounding enhances the production of beneficial compounds, improving ripeness, chemical composition, wine quality, and human health. More research is needed for optimal wounding strategies, environmental friendliness, berry ripening, and leaf photosynthetic responses to injury. This study contributes to the initial records of artificial wounding treatments, given their complexity and recent emergence in research.