RICE IS ONE OF THE MOST IMPORTANT CROPS GROWN GLOBALLY AND PROVIDES NUTRITION TO MORE THAN 3.5 BILLION PEOPLE. IN 2019, THE UNITED STATES HARVESTED APPROXIMATELY 2,472,000 ACRES OF RICE AT AN ESTIMATED VALUE OF $2.46 BILLION (USDA-NASS 2020). DISEASES CONTINUALLY THREATEN RICE PRODUCTION THROUGHOUT THE WORLD, LEADING TO THE OFTEN EXPENSIVE UNDERTAKING OF DISEASE MANAGEMENT. NARROW BROWN LEAF SPOT (NBLS), CAUSED BY THE FUNGAL PATHOGEN CERCOSPORA JANSEANA, IS A PERSISTENT THREAT TO RICE PRODUCTION IN THE UNITED STATES, INCLUDING THE PRODUCTION REGIONS OF LOUISIANA, ARKANSAS, TEXAS, MISSOURI, AND MISSISSIPPI. EPIDEMICS HAVE BEEN OBSERVED IN RECENT YEARS AND CAN LEAD TO YIELD LOSSES RANGING FROM 10-40% WHICH TRANSLATES TO A SUBSTANTIAL ECONOMIC LOSS. GENETIC RESISTANCE IS AN ECONOMICAND EFFECTIVE MEANS OF DISEASE CONTROL. UNFORTUNATELY, MANY OF THE POPULAR RICE CULTIVARS GROWN IN THE SOUTHERN UNITED STATES ARE SUSCEPTIBLE TO THIS DISEASE. THE MAIN GOAL OF THIS PROJECT IS TO THOROUGHLY CHARACTERIZE QUALITATIVE AND QUANTITATIVE RESISTANCE TO NBLS BY COMBINING CLASSICAL GENETICS, PLANT PATHOLOGY, GENOMICS, AND MOLECULAR BIOLOGY TECHNIQUES. THE IDENTIFICATION OF THE UNDERLYING RESISTANCE GENE AT THE CRSP2.1 LOCUS WILL LEAD TO THE DEVELOPMENT OF A PERFECT MARKER THAT CAN BE USED FOR MARKER-ASSISTED SELECTION IN BREEDING PROGRAMS TO DEVELOP NEW RESISTANT VARIETIES. ALSO, NOVEL QUANTITATIVE RESISTANCE LOCI WILL BE IDENTIFIED IN RECOMBINANT INBRED AND MULTI-PARENT ADVANCED GENERATION INTERCROSS POPULATIONS. THESE QUANTITATIVE RESISTANCE GENES CAN BE PYRAMIDED WITH QUALITATIVE GENES, LEADING TO DURABLE AND BROAD SPECTRUM RESISTANCE. ADDITIONALLY, RESULTS FROM THIS PROJECT WILL ADVANCE OUR BASIC UNDERSTANDING ON THE FUNCTION OF RESISTANCE TO FUNGAL PATHOGENS. OVERALL, THESE RESULTS WILL GREATLY AID RICE PRODUCTION BY ENABLING THE INTROGRESSION OF MULTIPLE NBLS RESISTANCE LOCI INTO ELITE RICE GERMPLASM AND LEAD TO MORE EFFECTIVE DISEASE MANAGEMENT.