** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** PSYLLIDS HAVE EMERGED AS VECTORS OF BACTERIAL PATHOGENS THAT COST MILLIONS OF DOLLARS ANNUALLY IN THE U.S. THE TOMATO PSYLLID BACTERICERA COCKERELLI TRANSMITS 'CANDIDATUS LIBERIBACTER SOLANACEARUM'THREATENING SOLANACEOUS CROPS, AND DIAPHORINA CITRI TRANSMITS 'CA. L. ASIATICUS', WHICH IS DECIMATING THE CITRUS INDUSTRY. TODAY, THE MAIN MANAGEMENT STRATEGY RELIES ON VECTOR CONTROL, AND PESTICIDE USE HAS INCREASED DRAMATICALLY. HOWEVER, NEW CONTROL STRATEGIES ARE URGENTLY NEEDED.BACTERIAL EFFECTORS ARE PROTEINS SECRETED BY PATHOGENS INTO THE HOST CELLS HELPING THE PATHOGEN COLONIZE THE HOST AND/OR SUPPRESS THE PLANT/VECTOR IMMUNE SYSTEM. THEY PLAY KEY ROLES IN PROMOTING PATHOGENICITY DURING THE INTERACTION OF PATHOGENS WITH PLANTS AND ARTHROPODS. TO COUNTERACT INFECTIONS, PLANTS AND INSECTS EVOLVED IMMUNE RECEPTORS TO RECOGNIZE THESE EFFECTORS AND TRIGGER IMMUNE RESPONSES. PROGRAMMED CELL DEATH IS A DEFENSE RESPONSE UPON RECOGNITION OF PATHOGEN EFFECTORS PREVENTING THE PATHOGEN FROM SPREADING IN THE HOST AND VECTOR. IN THIS PROPOSAL WE WILL IDENTIFY LIBERIBACTER EFFECTORS AND THEIR TARGETPROTEINS IN PLANTS AND PSYLLIDS. USING A VARIETY?OF APPROACHES, WE WILL EVALUATE THE ROLE OF THESE INTERACTORS IN PLANT INFECTION OR PATHOGEN TRANSMISSION AND WHETHER WE CAN USE THESE INTERACTIONS TO DISRUPT PLANT INFECTION OR PATHOGEN TRANSMISSION. THIS WORK IS ORIGINAL BECAUSE IT STUDIES IN PARALLEL PLANT AND INSECT IMMUNE SYSTEMS.