** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** IDENTIFYING RESISTANT GERMPLASM IS CRITICAL FOR REDUCING YIELD LOSSES DUE TO CROP DISEASES. I PROPOSE TO INVESTIGATE DISEASE RESISTANCE IN POPULATIONS OF MAIZE LANDRACES AND TEOSINTE, THE WILD RELATIVE OF MAIZE. MAIZE LANDRACE AND TEOSINTE POPULATIONS HAVE ADAPTED TO A WIDE RANGE OF ENVIRONMENTAL CONDITIONS AND DISPLAY REMARKABLE GENETIC AND PHENOTYPIC DIVERSITY. IN THIS PROJECT, I WILL DESCRIBE GENETIC VARIATION FOR DISEASE RESISTANCE IN POPULATIONS FROM ACROSS THE NATIVE RANGE OF MAIZE/TEOSINTE AND PERFORM GENOME WIDE ASSOCIATION ANALYSIS TO IDENTIFY ALLELES ASSOCIATED WITH RESISTANCE. TO UNDERSTAND MECHANISMS UNDERLYING DISEASE RESISTANCE I WILL MEASURE MULTIPLE COMPONENTS OF DISEASE RESISTANCE IN THESE POPULATIONS AND CORRELATIONS BETWEEN THESE TRAITS AND OVERALL DISEASE RESISTANCE. AS LANDRACES AND WILD RELATIVES HAVE EXPERIENCED HISTORICAL SELECTION FROM THEIR LOCAL ENVIRONMENTS, THEY PROVIDE AN OPPORTUNITY TO UNDERSTAND HOW AGRONOMICALLY IMPORTANT TRAITS HAVE EVOLVED. I WILL TEST SELECTION ON THESE TRAITS AND WHETHER THEY HAVE BEEN SHAPED BY ADAPTATION TO ENVIRONMENTAL FEATURES. FINALLY, I WILL INVESTIGATE THE TRANSCRIPTOMIC BASIS OF THE DEFENSE RESPONSE IN A SUBSET OF THESE POPULATIONS TO IDENTIFY GENES THAT ARE DIFFERENTIALLY EXPRESSED IN INFECTED AND UNINFECTED PLANTS. I WILL ASK WHETHER ENVIRONMENTALLY DISTINCT POPULATIONS HAVE DIFFERENT RESPONSES TO PATHOGENS. THIS PROJECT SUPPORTS THE USDA AFRI PROGRAM AREA PLANT HEALTH AND PRODUCTION AND PLANT PRODUCTS AND PRIORITY AREA PLANT BREEDING FOR AGRICULTURAL PRODUCTION BY IDENTIFYING ALLELES AND MECHANISMS UNDERLYING DISEASE RESISTANCE IN MAIZE AND ASSOCIATIONS BETWEEN ADAPTIVE TRAITS AND GROWING ENVIRONMENTS.