HEAT STRESS DUE TO HIGH TEMPERATURES FREQUENTLY CAUSES SIGNIFICANT YEAR-TO-YEAR VARIATION IN COTTON PRODUCTIVITY IN THE US. HEAT STRESS/HIGH TEMPERATURE TOLERANCE (HTT) IS COMPLEX AND AS SUCH NEED SYSTEMATIC GENETIC DISSECTION OF TARGET TRAITS TO LEVERAGE GENOMIC TOOLS AND GENETIC DIVERSITY FOR ACCELERATING HTT SELECTION IN COTTON. POLLEN IS EXCEPTIONALLY SENSITIVE TO HEAT STRESS DURING FLOWERING AS IT LIMITS POLLEN VIABILITY, GERMINATION, POLLEN TUBE GROWTH, FERTILIZATION OF OVULES, AND ULTIMATELY SEED AND FRUIT SET THROUGH EXCESSIVE ACCUMULATION OF REACTIVE OXYGEN SPECIES (ROS). STUDIES SHOWED PHYTOCHEMICALS, BY MAINTAINING ROS HOMEOSTASIS DURING HEAT STRESS, ENHANCE POLLEN VIABILITY, POLLEN TUBE GROWTH AND INTEGRITY IN MODEL CROPS AND FIBER QUALITY IN COTTON. OUR PRELIMINARY RESULTS SHOWED CAROTENOIDS, A CLASS OF PHYTOCHEMICALS, UNDERLIE POLLEN PIGMENTATION AND ANTHER DEHISCENCE UNDER HEAT STRESS IN COTTON. IN THIS PROJECT, WE AIM TO DETERMINE POLLEN CAROTENOIDS AS TARGET TRAITS FOR HTT AND FIBER QUALITY IN UPLAND COTTON. SPECIFIC OBJECTIVES OF THIS PROJECT ARE ESTABLISHING THE GENETIC ARCHITECTURE OF POLLEN CAROTENOIDS, DETERMINING THE ROLE OF CAROTENOIDS IN POLLEN GROWTH AND DEVELOPMENT UNDER HEAT STRESS, EVALUATING CORE SET ACCESSIONS FOR PHENOTYPIC TRAITS ASSOCIATED WITH HEAT STRESSED POLLEN, AND STUDYING THE EFFECT OF POLLEN CAROTENOIDS ON FIBER QUALITY IN COTTON. OUR RESEARCH WILL CONTRIBUTE TO THE LARGER ABIOTIC STRESS TOLERANCE COMMUNITY BY PROVIDING TRAITS AND GENETIC INFORMATION, WHICH HAS THE POTENTIAL TO IMPACT BREEDING IN MANY CROP PLANTS FREQUENTLY AFFECTED BY HEAT STRESS. OUTCOMES FROM THIS STUDY WILL HELP ENSURE SUSTAINABILITY AND ECONOMIC VIABILITY OF CROP PRODUCTION USING ADAPTED COTTON CULTIVARS.