**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** PLANTS NEED TO PERCEIVE AND RESPOND TO ENVIRONMENTAL CHANGES IN ORDER TO SURVIVE IN CHALLENGING ENVIRONMENTS. ROOTS SUPPORT THE PLANT THROUGH THE UPTAKE OF WATER AND MINERALS AND ARE SUSCEPTIBLE TO STRESSORS CAUSED BY SUB-OPTIMAL GROWING CONDITIONS. AS CLIMATE CHANGE AFFECTS WATER AVAILABILITY, ENGINEERING PLANTS ABLE TO MAINTAIN YIELD IN WATER-DEFICIENT AND HIGH SALINITY CONDITIONS IS NECESSARY FOR MAINTAINING FOOD SECURITY. ONE WAY PLANT CELLS TRANSDUCE EXTERNAL STIMULI INTO SIGNAL TRANSDUCTION PATHWAYS IS THROUGH CALCIUM SIGNALING. IN ROOTS, CHANGES IN CA2+ ARE INVOLVED IN SIGNALING RESPONSE TO ABIOTIC STRESSORS INCLUDING OSMOTIC AND SALT STRESS. OUR LAB HAS DEVELOPED TOOLS TO MANIPULATE THE SUBCELLULAR LOCALIZATION AND REGULATION OF THE PLANT-SPECIFIC MILDEW RESISTANCE LOCUS O CA2+ CHANNEL FAMILY. MY CENTRAL HYPOTHESIS IS THAT INCREASING CA2+ LEVELS IN ROOTS THROUGH CONSTITUTIVE ACTIVATION OF MLOS CAN BE USED TO INCREASE PLANT RESILIENCY BY PRIMING CELLS TO BE READY TO RESPOND TO ENVIRONMENTAL STRESS AND PROMOTING ROOT HAIR ELONGATION. THE FOLLOWING OBJECTIVES WILL TEST WHETHER ALTERING CA2+ LEVELS CAN INCREASE PLANT RESILIENCY BY MANIPULATING MLO EXPRESSION, LOCALIZATION, AND REGULATION IN ARABIDOPSIS AND TOMATO. OBJECTIVE 1: MANIPULATE MLO SUBCELLULAR LOCALIZATION AND REGULATION TO INCREASE CYTOSOLIC CA2+ LEVELS IN ARABIDOPSIS ROOTS. OBJECTIVE 2: DETERMINE WHETHER THERE IS A CONSERVED FUNCTION FOR MLOS IN ROOT DEVELOPMENT AND STRESS RESPONSE IN SOLANUM LYCOPERSICUM. TOGETHER, THIS RESEARCH WILL HELP IMPROVE UNDERSTANDING OF THE ROLE OF CA2+ IN ROOT DEVELOPMENT AND IN RESPONSE TO SALT STRESS AND WHETHER MLOS ARE GOOD CANDIDATES FOR INCREASING RESILIENCE TO ABIOTIC STRESS IN CROP SPECIES.