** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** RICE IS A STAPLE FOR ~HALF OF THE WORLD'S POPULATION AND IS AN IMPORTANT CONTRIBUTOR TO THE U.S. ECONOMY. BACTERIAL LEAF STREAK (BLS), CAUSED BY THE BACTERIUMXANTHOMONAS ORYZAEPV. ORYZICOLA (XOC), IS A THREAT TO RICE PRODUCTION IN MOST RICE-GROWING REGIONS OF THE WORLD. XOC HAS NOT YET BEEN FOUND IN THE U.S.AND ISA FEDERAL SELECT AGENT OR CONSIDERED TO BE A THREAT TO RICE HEALTH IN THE U.S. XOC, LIKE MOST OTHER BACTERIA IN THE SAME GENUS, CARRY PROTEINS CALLED TRANSCRIPTION ACTIVATOR-LIKE EFFECTORS (TALES) THAT THEY INJECT INTO RICE CELLS. TALES CAN TRAVEL TO THE RICE NUCLEUS AND ACTIVATE RICE GENES BENEFICIAL FOR THE BACTERIA. HOWEVER, RICE IS NOT DEFENSELESS AGAINST TALE-CARRYING XOC. A U.S. RICE VARIETY, CAROLINA GOLD SELECT, CARRIES AN IMMUNE RECEPTOR CALLED XO1 THAT DETECTS TALES INJECTED INTO RICE CELLS AND LAUNCHES A DEFENSE RESPONSE. IF XO1 IS PRESENT IN RICE, IT CAN STOP THE PATHOGEN FROM CAUSING BLS. EVEN MORE IMPORTANTLY, XO1 CAN DETECT MANY TYPES OF TALES, MAKING IT A PROMISING SOURCE OF BROAD-SPECTRUM RESISTANCE AGAINST MANY TYPES OF XOC STRAINS, BUT ALSO OTHER XANTHOMONAS PATHOGENS OF CROP PLANTS. INTERESTINGLY, THERE ARE SOME TALES FROM DIFFERENT SPECIES OF XANTHOMONAS THAT EVADE DETECTION BY XO1. FURTHERMORE, A SUBSET OF XOC STRAINS HAVE EVOLVED A NEW TYPE OF SHORTENED TALE (TRUNCTALE) THAT, WHEN INJECTED INTO THE RICE CELL, COMPLETELY SHUTS DOWN XO1'S ABILITY TO DETECT TALES AND DEFEND AGAINST XOC. RESEARCHERS DON'T YET KNOW HOW XO1 DETECTS SOME BUT NOT ALL TALES TO TRIGGER IMMUNITY, OR HOW TRUNCTALES INHIBIT XO1 TO SHUT DOWN IMMUNITY AND FACILITATE DISEASE. THIS PROJECT AIMS TO UNCOVER WHAT IS OCCURRING BETWEEN THESE PROTEINS. FINDINGS FROM THIS PROJECT WILL SUPPORT THE BROADER, FUTURE GOAL OF ENGINEERING XO1 TO DETECT AN EVEN WIDER VARIETY OF TALES FROM OTHER AGRICULTURALLY RELEVANT XANTHOMONAS PATHOGENS OR TO RESIST DEFENSE SUPPRESSION BY TRUNCTALES.TO INVESTIGATE HOW XO1 DETECTS TALES AND TRUNCTALES INHIBIT XO1, WE WOULD LIKE TO KNOW WHAT COMPONENTS OF THE TALES AND TRUNCTALES ARE REQUIRED FOR THEIR RESPECTIVE ACTIVITIES. I WILL FIRST PERTURB PREDICTED REGIONS OF IMPORTANCE OR SWAP REGIONS BETWEEN TALES AND TRUNCTALES. XOC CARRYING EACH OF THESE MUTANT PROTEINS WILL BE INOCULATED ONTO CAROLINA GOLD SELECT RICE TO MEASURE THE LEVEL OF DISEASE OR RESISTANCE. I WILL TAKE A SIMILAR APPROACH OF PERTURBING PREDICTED IMPORTANT REGIONS OF XO1 AND SEEING WHETHER THOSE MUTATIONS IMPACT XO1'S ABILITY TO DETECT TALES OR BE INHIBITED BY TRUNCTALES. IN PLANTS, I WILL ALSO IDENTIFY HOW XO1 INTERACTS WITH TALES AND TRUNCTALES. BY IDENTIFYING PARTS OF TALE, TRUNCTALE, AND XO1 PROTEINS THAT ARE IMPORTANT FOR DISEASE OR IMMUNITY, AND BETTER UNDERSTANDING HOW EACH COMPONENT MIGHT INTERACT WITH EACH OTHER, WE CAN SHED LIGHT ON HOW XO1 OPERATES. NOT ONLY WILL THESE FINDINGS ILLUMINATE AN UNCHARACTERIZED IMMUNE RECEPTOR MECHANISM, BUT IT WILL ALSO ALLOW US TO CONCEPTUALIZE HOW WE MIGHT ENGINEER XO1 FOR ENHANCED DISEASE RESISTANCE AG,AINST XOC AND OTHER XANTHOMONAS PATHOGENS.