** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE AMERICAN PEANUT COUNCIL HAS IDENTIFIED DROUGHT AS THE TOP CHALLENGE FACING THE PEANUT INDUSTRY AS ONLY 35% OF GROWERS IN THE U.S. HAVE IRRIGATION CAPABILITIES. FOR THIS REASON, BREEDING FOR DROUGHT TOLERANCE IS PARAMOUNT FOR THE PEANUT INDUSTRY. IN PREVIOUS WORK, WE HAVE IDENTIFIED CULTIVARS THAT USE TWO DIFFERENT STRATEGIES (WATER SPENDERS AND WATER SAVERS) TO MAINTAIN HIGH YIELDS UNDER DROUGHT. HOWEVER, THE PHYSIOLOGICAL AND GENETIC MECHANISMS CONTROLLING THESE TWO STRATEGIES ARE NOT KNOWN. IN OTHER CROPS, THESE TWO MECHANISMS RESULTED IN INCREASED YIELDS UNDER SPECIFIC ENVIRONMENTAL CONDITIONS. IN THIS PROJECT, WE WILL PERFORM DETAILED PHYSIOLOGICAL AND RNA-SEQUENCING EXPERIMENTS IN PEANUTS UNDER TWO RAIN-OUT SHELTER FACILITIES TO FULLY UNDERSTAND THE PHYSIOLOGICAL AND GENETIC MECHANISMS OF WATER-SAVER AND WATER-SPENDER DROUGHT-TOLERANT CULTIVARS. IN ADDITION, WE WILL USE A RIL POPULATION DERIVED FROM THE CROSS OF A WATER SAVER WITH A WATER SPENDER LINE TO FIND GENOMIC REGIONS (QTL) THAT RELATE TO WATER SAVING OR SPENDING STRATEGIES AND THAT CAN BE USED TO BREED FOR DROUGHT TOLERANCE USING MARKER-ASSISTED SELECTION. WE WILL ALSO USE THE DATA PRODUCED IN THE DETAILED PHYSIOLOGICAL EXPERIMENTS TO MODIFY A PEANUT MODEL THAT CAN PREDICT THE PERFORMANCE OF EACH VARIABLE TYPE UNDER CURRENT AND FUTURE ENVIRONMENTS TO DETERMINE ENVIRONMENTS THAT FAVOR ONE MECHANISM OVER ANOTHER. WITH THIS APPROACH, WE WILL FACILITATE THE SELECTION OF CULTIVARS WITH DIFFERENT DROUGHT-TOLERANT STRATEGIES THAT WITH THE HELP OF CROP MODELING, CAN BE TAILORED TO YIELD MORE UNDER DIFFERENT ENVIRONMENTS IN THE SOUTHEAST U.S.