**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** CURRENT ISSUEMOST PLANT PATHOGENS PRODUCE MOLECULES CALLED EFFECTORS, WHICH ARE INTRODUCED INTO THE PLANT CELL TO FACILITATE THE DISEASE PROCESS. PLANTS IN TURN CARRY NUCLEOTIDE-BINDING LEUCINE RICH REPEAT (NLR) PROTEINS WHICH, UPON RECOGNITION OF SPECIFIC EFFECTORS, TRIGGER A DEFENSE RESPONSE CALLED EFFECTOR-TRIGGERED IMMUNITY, OFTEN INCLUDING A HYPERSENSITIVE RESPONSE (HR), A RAPID CELL DEATH AT THE POINT OF INFECTION. THE MAIZE RP1-D GENE ENCODES FOR AN NLR RESISTANCE PROTEIN THAT CONFERS RESISTANCE TO COMMON RUST DISEASE CAUSED BY THE FUNGUS PUCCINIA SORGHI. WE PREVIOUSLY IDENTIFIED SEVERAL HOST PROTEINS RESPONSIBLE FOR CONTROLLING THE ACTIVITY OF RP1-D21, AN AUTO-ACTIVE VERSION OF RP1-D WHICH TRIGGERS THE DEFENSE RESPONSE CONSTANTLY REGARDLESS OF WHETHER THE PATHOGEN IS PRESENT OR NOT. THIS CAUSES WHAT CAN BE THOUGHT OF AS AN AUTOIMMUNE CONDITION. WE WOULD LIKE TO UNDERSTAND MORE COMPLETELY HOW THE ACTIVITY OF RP1-D IS CONTROLLED. WE WOULD ALSO LIKE TO UNDERSTAND THE MOLECULAR MECHANISMS THAT ALLOW THE PATHOGEN TO INFECT THE PLANT. THIS SHOULD GIVE US SOME INSIGHT INTO PLANT RESISTANCE MECHANISMS IN GENERAL.METHODS AND APPROACHESIN THIS PROJECT, WE WILL USE A NUMBER OF COMPUTATIONAL AND WET-LAB APPROACHES TO IDENTIFY AND ANALYZE THE MOLECULAR COMPONENTS OF THE INTERACTION THAT COME FROM P. SORGHI AS WELL AS OTHER IMPORTANT HOST-DERIVED COMPONENTS. WE WILL IDENTIFY EFFECTORS ASSOCIATED WITH THE CONTROL OF HOST CELL DEATH AND SUPPRESSION OF THE HOST DEFENSE RESPONSE. WE WILL DEFINE HOW THESE EFFECTORS INFLUENCE IMPORTANT PHYSIOLOGICAL CHANGES IN HOST CELLS, SUCH AS CHANGES IN PH, REACTIVE OXYGEN SPECIES PRODUCTION, AND CALCIUM FLUX, AND WILL CHARACTERIZE THEIR SUBCELLULAR LOCALIZATIONS. WE WILL ALSO EXAMINE THE MAIZE HR WITH RESPECT TO THESE SAME PHYSIOLOGICAL CHANGES AND THE ORGANELLE DYNAMICS IN THE CELL. WE WILL EXAMINE THE FORMATION OF STROMULES, NARROW STROMA-FILLED TUBES THAT EXTEND FROM PLASTIDS, OFTEN CONNECTED TO OTHER SUBCELLULAR COMPARTMENTS, INCLUDING THE NUCLEUS, THAT ARE BELIEVED TO FACILITATE THE EXCHANGE OF SIGNALING COMPONENTS BETWEEN THE PLASTIDS AND NUCLEUS DURING HR. FINALLY, WE WILL CHARACTERIZE THE PHYSICAL INTERACTIONS OF ALL THE HOST- AND PATHOGEN-DERIVED COMPONENTS THAT INTERACT WITH RP1-D AND ARE LIKELY TO CONSTITUTE COMPONENTS OF THE RP1-D SIGNALING COMPLEX, THE 'RESISTOSOME'.ULTIMATE GOALSDESPITE SIGNIFICANT PROGRESS, THERE REMAINS MUCH TO LEARN ABOUT NLR-MEDIATED RESISTANCE. THIS IS PARTICULARLY TRUE IN MONOCOTS LIKE MAIZE. THIS PROJECT EMPLOYS STATE-OF-THE-ART BIOCHEMICAL AND CELL BIOLOGY TECHNIQUES TO AUGMENT AND EXTEND OUR UNDERSTANDING OF THE CONTROL OF THE DEFENSE RESPONSE MEDIATED BY RP1-D FOCUSING ON PATHOGEN DERIVED COMPONENTS. THIS WILL RESULT IN AN UNDERSTANDING OF THE CONTROL OF THE NLR-MEDIATED RESPONSE THAT IS UNIQUE IN MAIZE AND AMONG THE MOST DETAILED IN ANY PLANT SPECIES.THE PROPOSED RESEARCH WILL ELUCIDATE A PIVOTAL DEFENSE MECHANISM IN MAIZE WHICH IS BOTH A MODEL SPECIES FOR PLANT QUANTITATIVE GENETICS AND THE NUMBER ONE CROP IN THE U.S. OUR RESULTS WILL BE OF DIRECT RELEVANCE TO EFFORTS TO GENETICALLY IMPROVE THIS IMPORTANT CROP. SINCE THE HR IS A GENERAL DEFENSE RESPONSE FOUND IN ALL MULTICELLULAR PLANTS, OUR FINDINGS WILL BE RELEVANT TO IMPROVING OTHER IMPORTANT CROP SPECIES, PARTICULARLY OTHER GRASSES. OUTREACH ACTIVITIES WILL EDUCATE THE PUBLIC ON GENETICS, PLANT BREEDING, BIOTECHNOLOGY, AND ASSOCIATED SOCIETAL IMPLICATIONS. THEY BUILD ON EXISTING SUCCESSFUL PROGRAMS THAT HAVE DEVELOPED SEVERAL INSTRUCTIONAL MODULES FOR TEACHERS AND STUDENTS.