** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** GRAPEVINE FREEZE DAMAGE THREATENS GRAPE PRODUCTION GLOBALLY. AS GRAPE BUDS EMERGE FROM WINTER DORMANCY AND APPROACH BUDBREAK, THEY LOSE COLD TOLERANCE (DEACCLIMATE) AND BECOME INCREASINGLY SUSCEPTIBLE TO LOW TEMPERATURE DAMAGE. GRAPE BUDS CONTAIN CROP POTENTIAL FOR THE ANNUAL GROWING SEASON, AND LOW TEMPERATURE DAMAGE CAN CAUSECONSIDERABLE ECONOMIC LOSS FOR GRAPE GROWERS. GLOBAL WARMING IS EXPECTEDTO ADVANCE THE RATE OF BUD DEACCLIMATION AND TIME OF BUDBREAK IN SPRING, BUT SPRING FREEZE EVENTS ARE NOT PROJECTED TO DECREASE UNIFORMLY. IN ORDER TO ADAPT TO GLOBAL WARMING AND THE RESULTING CHANGES TO EARLY SEASON PHENOLOGY, WE MUST ADVANCE OUR FUNDAMENTAL KNOWLEDGE OF GRAPEVINE DORMANCY AND BUD COLD TOLERANCE AND CREATE MITIGATION STRATEGIES FOR GRAPE GROWERS.THE PROPOSED RESEARCHWILL INVESTIGATE THE ROLE OF THE PLANT HORMONE ABSCISIC ACID (ABA) IN REGULATING DORMANCY AND COLD TOLERANCE IN GRAPE BUDS ACROSS DIFFERENT GENOTYPES RELEVANT TO US PRODUCTION.THE PROPOSED EXPERIMENTS WILL TEST WHETHER THE APPLICATION OF A SYNTHETIC ABA PRODUCTIN AUTUMN INITIATES FASTER COLD ACCLIMATION AND HIGHER BUD COLD TOLERANCE UNDER AMBIENT CONDITIONS. IN SIMULATION OF GLOBAL WARMING, THE PROPOSED RESEARCH WILL ALSO TEST IF THE SYNTHETIC ABA PRODUCT EFFECTIVELY DELAYSBUD DEACCLIMATION AND BUDBREAK IN SPRING UNDER AMBIENT AND WARMER TEMPERATURE SCENARIOS.TOGETHER, RESEARCH OUTCOMES FROM THIS GRANTWILL ADVANCE SCIENTIFIC KNOWLEDGE ON THE ROLE OF ABA IN GRAPEVINES AND IMPROVE GROWER-FOCUSED OUTCOMES (E.G., PLANT BREEDING AND PRODUCT DEVELOPMENT) FOR CLIMATE ADAPTATION IN VINEYARDS.