** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** CLIMATE CHANGE IS A CRITICAL GLOBAL CONCERN FACED BY FARMERS IN THE 21ST CENTURY. DRYLAND CROPPING SYSTEMS OCCUPY OVER 40% OF THE LAND SURFACE OF THE EARTH AND ARE ESPECIALLY VULNERABLE TO DROUGHTS, TEMPERATURE FLUCTUATIONS, FERTILITY LOSS, AND EROSION ASSOCIATED WITH CLIMATE CHANGE. DRYLANDS ARE INHABITED BY HALF A BILLION PEOPLE AND PROVIDE AN IMPORTANT SOURCE OF PASTURE FOR LIVESTOCK, LEGUMES, AND CEREALS. THE CHALLENGES OF FARMING IN DRYLAND AGROECOSYSTEMS HAVE BEEN ADDRESSED THROUGH THE USE OF DROUGHT-ADAPTED CROPS, SOIL COVER BY RESIDUES OR COVER CROPS, NOVEL ROTATIONS, AND CONSERVATION TILLAGE. HOWEVER, THE PROGRESS IN THE BREEDING OF DROUGHT-ADAPTED CULTIVARS REMAINS SLOW, WHILE CONSERVATION TILLAGE OFTEN EXACERBATES SOILBORNE DISEASES, RESULTING IN GREATER YIELD LOSSES COMPARED TO CONVENTIONAL MANAGEMENT PRACTICES. RECENT STUDIES DEMONSTRATED THAT MICROORGANISMS ASSOCIATED WITH PLANT ROOTS POSITIVELY INFLUENCE CROP FITNESS IN RESPONSE TO THE DETRIMENTAL EFFECTS OF CLIMATE CHANGE. ROOT-ASSOCIATED MICROBES STIMULATE NUTRIENT UPTAKE AND GROWTH, SUPPRESS PATHOGENS, AND ENHANCE THE ABILITY OF PLANTS TO RESIST HEAT AND DROUGHT. HOWEVER, THE MOLECULAR DETAILS OF THESE PROCESSES ARE STILL VERY MUCH A BLACK BOX.THIS PROJECT WILL ADDRESS THESE QUESTIONS BY FOCUSING ON THE SEMI-ARID INLAND PACIFIC NORTHWEST (IPNW), USA. THIS REGION EXPERIENCES AN UNPRECEDENTED HEAT WAVE AND DROUGHT AND PROVIDES AN EXCELLENT MODEL FOR STUDYING THE INTERDEPENDENCE OF CROPS AND THEIR ASSOCIATED MICROBIOTA UNDER WATER STRESS. THE PROJECT WILL USE A COMBINATION OF DNA-BASED APPROACHES, INSTRUMENTAL ANALYSIS, AND MICROBIOME MANIPULATION TO UNDERSTAND HOW WATER STRESS AND MONOCULTURE SHAPE THE INTERACTIONS BETWEEN TWO ECONOMICALLY IMPORTANT IPNW CROPS (WHEAT AND ALFALFA), SOIL MICROORGANISMS, AND SOILBORNE PATHOGENS. THIS RESEARCH WILL CHARACTERIZE THE MECHANISMS THROUGH WHICH PLANTS RECRUIT BENEFICIAL MICROORGANISMS AND HELP TO PREDICT HOW CLIMATE CHANGE COULD IMPACT THE PRODUCTIVITY OF AGROECOSYSTEMS WORLDWIDE.