Tetralone-ABA enhances winter cold acclimation, reduces deacclimation, and delays budbreak in V. vinifera and V. hybrid grapevines

• Tetralone-ABA accelerated chlorophyll degradation and defoliation in grapevine. • Tetralone-ABA enhanced cold acclimation and slowed deacclimation. • Tetralone-ABA delayed budbreak without impacting growing season physiology or yield. • There was a cultivar-specific response to tetralone-ABA treatment. • Tetralone-ABA delayed the activation of growth-related pathways during deacclimation. Climate change-related acute winter freezes and unseasonal false springs have become significant and predictable risks for grape growers across North America and Eurasia. Novel strategies to enhance resilience during the dormant season, particularly by improving bud cold hardiness and delaying budbreak, are urgently needed for the sustainability of grape and wine production. In this study, we evaluated a synthetic abscisic acid (ABA) analog, tetralone-ABA (ABA-1102), as a sprayable product for inducing these traits in three grapevine cultivars: ‘Riesling’, ‘Cayuga White’, and their progeny, ‘Aravelle’. Post-harvest foliar application of tetralone-ABA accelerated leaf senescence, enhanced bud cold hardiness during cold acclimation, and slowed deacclimation under both controlled and field conditions. It also delayed the budbreak in spring without altering growing season phenology, physiology, or harvest yield. Transcriptomic analysis during deacclimation assays suggests that tetralone-ABA’s effect on delaying deacclimation may result from its suppression of the activation of growth-related pathways under growth-permissive conditions. Detailed investigations of these pathways indicate that tetralone-ABA may have modulated critical biological processes such as cell wall remodeling, sugar metabolism, and ABA signaling. Overall, this study provides novel insights into the genetic control of grapevine deacclimation, highlights ABA’s role in grapevine dormant season physiology, and demonstrates tetralone-ABA’s potential as a promising tool for improving dormant season viticulture resilience, offering a new strategy to protect grapevines against the increasing threats posed by climate change.