** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THIS PROJECT FITS WELL IN THE NIFA PROGRAM AREA PRIORITY OF PESTS AND BENEFICIAL SPECIES INAGRICULTURAL PRODUCTION SYSTEMS AND ADDRESSES THE HATCH ACT AREA OF PLANT AND ANIMAL PRODUCTION, PROTECTION, AND HEALTH. THIS PROJECT WILL LEAD TO ADVANCED KNOWLEDGE OF AN ESTABLISHED PLANT PATHOGEN AND A BETTER UNDERSTANDING OF THE BROADER UMBRELLAS OF VASCULAR PLANT PATHOGENS AND GRAM-POSITIVE BACTERIA. THE PROJECT FOCUS ON CLAVIBACTER, A GENUS OF GRAM-POSITIVE, XYLEM-COLONIZING BACTERIA CONTAINING EIGHT IMPORTANT PLANT PATHOGENS. C. MICHIGANENSIS IS THE MOST WELL-KNOWN AND DESTRUCTIVE OF THESE, CAUSING SEVERE DISEASE OUTBREAKS IN PROCESSING AND FRESH-MARKET TOMATOES. MANAGEMENT OF CLAVIBACTER DISEASES HAS HISTORICALLY BEEN ATTEMPTED WITH SEED STERILIZATION, SEED TREATMENT, AND QUARANTINE. HOWEVER, NO CONTROL METHOD PROVIDES A COMPLETE SOLUTION. PLANT PATHOGENS ARE GENERALLY MOST EFFECTIVELY MANAGED VIA PLANT RESISTANCE, BUT NO GENES CONTROLLING RESISTANCE TO CLAVIBACTER HAVE BEEN CLONED AND NO GENETIC RESISTANCE TO C. MICHIGANENSIS HAS BEEN FOUND IN PROCESSING TOMATOES.COMPLETION OF THIS PROJECT WILL RESULT IN A GREATER UNDERSTANDING OF THE INTERACTIONS BETWEEN GRAM-POSITIVE BACTERIAL PATHOGENS AND PLANTS. DESPITE THE IMPORTANCE OF GRAM-POSITIVE PLANT PATHOGENS, NO IMMUNE RECEPTORS HAVE BEEN IDENTIFIED. AIM 1 OF THE PROJECT WILL IDENTIFY AND CHARACTERIZE A RECEPTOR FOR A CLAVIBACTER-SECRETED EFFECTOR, MARKING THE DISCOVERY OF THE FIRST PLANT RECEPTOR FOR A GRAM-POSITIVE BACTERIUM. AIM 2 WILL CONTRIBUTE TO THE UNDERSTANDING OF PLANT DEFENSE TO VASCULAR PLANT PATHOGENS. UNDERSTANDING THE ROLE OF DAMAGE RECEPTORS IN THE RESTRICTION OF VASCULAR PATHOGENS CAN INFORM BREEDING DECISIONS FOR RESISTANT TRAITS. THE IDENTIFICATION OF A CLAVIBACTER RECEPTOR AND ITS TRANSFER INTO TOMATO WILL HAVE SIGNIFICANT IMPLICATIONS FOR DISEASE RESISTANCE BREEDING, AS WELL AS PROVIDE VALUABLE INSIGHT INTO THE MECHANISMS BEHIND GRAM-POSITIVE PATHOGENICITY.