** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** WITH THE GROWING POPULATION AND LIMITS ON ARABLE LANDS, AGRICULTURE STRUGGLES TO INCREASE THE YIELD AND QUALITY OF FOOD, FIBER, AND BIOFUEL CROPS. REDUCING CROP DISEASE LOSSES IS A KEY TO ADDRESSING THIS CHALLENGE. EFFECTIVE DISEASE MANAGEMENT RELIES ON A MECHANISTIC UNDERSTANDING OF PATHOGEN POPULATION DYNAMICS, VIRULENCE BASIS, AND HOST RESISTANCE DETERMINANTS IN THE FIELD. THE PROJECT IS ROOTED IN A RECENT DISEASE OUTBREAK OF COTTON FUSARIUM WILT CAUSED BY FUSARIUM OXYSPORUM F. SP. VASINFECTUM (FOV) IN SOME SOUTHERN U.S. STATES. WITH MULTIPLE CONSECUTIVE YEARS OF PATHOGEN CHARACTERIZATION AND GERMPLASM SCREENS FROM A NATURALLY INFECTED COTTON FIELD IN EL PASO COUNTY, TEXAS, THE TEAM HAS OBTAINED COMPREHENSIVE FIELD AND LABORATORY DATA FOR RAISING THE COMPELLING HYPOTHESIS ABOUT THE EVOLUTION AND PATHOGENICITY OF F. OXYSPORUM, BUILDING THE INVALUABLE RESOURCES FOR RESISTANCE GENE IDENTIFICATION, AND PROVIDING THE MOLECULAR INSIGHTS OF F. OXYSPORUM-HOST INTERACTIONS. IN ADDITION, THE TEAM HAS DEVELOPED MULTIPLE PLATFORMS FOR TRANSIENT AND STABLE LOSS- AND GAIN-OF-FUNCTION ASSAYS IN COTTON. WITH THESE ADVANCES, THE TEAM AIMS TO REVEAL THE COMPLEX MECHANISMS OF FUNGAL PATHOGENICITY AND HOST RESISTANCE BY DETERMINING 1) THE GENETIC DIVERSITY, EVOLUTION, AND PATHOGENICITY OF FOV AND COMPARATIVE GENOMICS OF F. OXYSPORUM SPECIES COMPLEX (FOSC), AND 2) COTTON RESISTANCE MECHANISMS TO FUSARIUM WILT BY TARGETED SEQUENCING AND ASSOCIATION GENOMICS. THE RESEARCH REPRESENTS A SYSTEMS APPROACH TO DECIPHERING CO-EVOLUTIONARY DYNAMICS OF PATHOGEN VIRULENCE AND HOST RESISTANCE IN THE COMPLEX GENOME OF A DEVASTATING PATHOGEN AND AN ESSENTIAL CROP.