COTTON (GOSSYPIUM SPP.) IS AN IMPORTANT CASH CROP WORLDWIDE AND A SIGNIFICANT SOURCE OF FIBER, FEED, FOODSTUFF, OIL AND BIOFUEL PRODUCTS. BACTERIAL BLIGHT OF COTTON (BBC), CAUSED BY XANTHOMONAS CITRI PV. MALVACEARUM (XCM), IS AMONG THE MOST DEVASTATING DISEASES OF COTTON. FOLLOWING SEVERE EPIDEMICS IN THE 1970S THAT CAUSED YIELD LOSSES OF UP TO 40%, THE DISEASE HAS OCCURRED SPORADICALLY IN THE US, BUT SINCE 2011 IT HAS AGAIN BECOME A SIGNIFICANT YIELD CONSTRAINT. GENETIC STUDIES HAVE REVEALED THAT THE COTTON-XCM INTERACTION IN GENERAL COMPLIES WITH THE GENE-FOR-GENE CONCEPT IN WHICH RESISTANCE IS TRIGGERED WHEN THE PATHOGEN POSSESSES AN AVIRULENCE (AVR) GENE AND THE HOST CARRIES A CORRESPONDING RESISTANCE (R) GENE. IN NON-RESISTANT GENOTYPES, PATHOGEN AVR GENE PRODUCTS MAY FUNCTION AS PATHOGENICITY (PTH) FACTORS TARGETING HOST SUSCEPTIBILITY (S) GENES IMPORTANT FOR DISEASE. BEFORE OUR MOST RECENT WORK, NO R OR S GENES FOR ANY DISEASE HAD BEEN ISOLATED FROM COTTON, AND THE MOLECULAR MECHANISMS UNDERLYING COTTON RESISTANCE AND SUSCEPTIBILITY TO XCM REMAIN POORLY UNDERSTOOD. THIS PROJECT WILL STUDY AND ISOATE THE COTTON R AND S GENES MEDIATING COTTON RESPONSES TO XCM INFECTION. THE WORK WILL PROVIDE STRATEGIC DEVELOPMENT TO IMPROVE COTTON RESISTANCE TO BACTERIAL BLIGHT AND LEVERAGE OUR UNDERSTANDING TO THIS COMPLEX HOST-PATHOGEN INTERACTION.