Ethanol reduces grapevine water consumption by limiting transpiration

Studies suggest that ethanol (EtOH), triggers plant adaptation to various stresses at low concentrations (10 microM 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 microM 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 EtOH solutions (0.4 and 250 mM) exhibited slower depletion of the fraction of transpirable soil water (FTSW), compared to controls. While 0.4 and 250 mM EtOH tended to decrease 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, and increased root dry mass. The grapevine responses to EtOH priming followed typical hormesis curves. RNA-seq data revealed transcripts related to this EtOH priming effect. 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.