Ethanol reduces grapevine water consumption by limiting transpiration

Studies suggest that ethanol (EtOH), triggers plant adaptation to various stresses at low concentrations (10 µM to 10 mM). This study investigates whether EtOH induces drought acclimation in grapevine, as demonstrated previously in Arabidopsis , rice, and wheat. Preliminary results with bare root Gamay cuttings showed that those pre-treated with 10 µM EtOH aqueous solutions lost fewer leaves when deprived of water compared to controls. Subsequently, we ran a potted-cutting experiment with progressive soil water deficit. Plants pre-treated with 250 mM EtOH solutions exhibited slower depletion of the fraction of transpirable soil water (FTSW), compared to controls. While 250 mM EtOH decreased transpiration in early days, these EtOH pre-treated plants maintained higher leaf transpiration than controls after 10 days of soil water depletion. The transpiration response to FTSW was affected by EtOH application. EtOH pre-treatments limited plant leaf expansion without increasing leaf senescence. Interestingly, plants primed with EtOH followed typical hormesis curves. These results suggest that EtOH improves grapevine acclimation to drought, leading to potential water-savings in wine growing regions prone to high water shortages, linked to climate change. These should encourage further testing under various vineyard conditions.