UNTIL RECENTLY, MOST IMMUNE RECEPTOR-EPITOPE RESEARCH FOCUSED ON THE BIOCHEMISTRY OF SINGLE SPECIES, SINGLE GENE, AND OFTEN SINGLE EPITOPE INTERACTION. THIS PROVIDED A FOUNDATIONAL UNDERSTANDING OF HOST-MICROBE INTERACTIONS HOWEVER OVERLOOKED THE DIVERSITY AND COMPLEXITY OF BACTERIAL EPITOPES AND ASSOCIATED PLANT RECEPTORS REVEALED BY MODERN GENOME SEQUENCING. FOR MOST RECEPTOR-EPITOPES, THE DIVERSITY AND EVOLUTION OF RECEPTORS AND THEIR LIGANDS AS WELL AS OUR ABILITY TO PREDICT THE INTERACTION OUTCOME REMAINS ELUSIVE. SOLVING THIS CHALLENGE COULD LEAD TO PRACTICAL TOOLS FOR DESIGNING DISEASE-RESISTANT CROPS AND PREDICTING FUTURE GENETIC RESISTANCE AS PATHOGENS EVOLVE. THIS PROJECT FOCUSES ON UNDERSTANDING HOW CSP22 RECEPTOR DIVERSITY AND EVOLUTION AFFECT PLANT IMMUNE RESPONSES. THE PROPOSED WORK CAN PROVIDE INSIGHT INTO THE FOLLOWING QUESTIONS: 1) HOW DO MULTICOPY LIGANDS SUCH AS CSP22 IMPACT RECEPTOR DIVERSIFICATION? 2) HOW DOES CORE RECEPTOR DIVERSITY COMPARE TO OTHER RECEPTORS OF THE SAME CLASS SUCH AS THE FLAGELLIN RECEPTORS FLS2 AND FLS3? 3) HOW DOES PEPTIDE VARIANT OUTCOMES CHANGE ACROSS PLANT SPECIES? AND 4) ARE THERE PREVIOUSLY UNDISCOVERED CORE HOMOLOGS ALREADY EVOLVED FOR IMPROVED RESISTANCE AND POTENTIAL DEPLOYMENT AGAINST BACTERIAL PATHOGENS? IN TANDEM, WE AIM TO BUILD ML TOOLS WHICH WILL SPEED UP RECEPTOR DISCOVERY, CHARACTERIZE THE BIOCHEMICAL PROPERTIES OF CONVERGENT EVOLVED RECEPTORS, AND PROVIDE A FRAMEWORK ON HOW NATURAL VARIATION CAN BE USED AND ENGINEERED FOR PATHOGEN RESISTANCE.?