**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** FLOWERING PLANTS HAVE EVOLVED UNIQUE STRATEGIES TO FACILITATE THE ESSENTIAL INTERPLAY BETWEEN THEIR MALE AND FEMALE COMPONENTS THAT ARE CRUCIAL FOR PLANT REPRODUCTION TO PRODUCE SEEDS THAT SERVE AS A FOOD SOURCE FOR ANIMALS. ONCE POLLEN GRAINS LAND ON THE STIGMA, A POLLEN TUBE BEGINS TO GROW. THE GROWTH OF THE POLLEN TUBE IS CRUCIAL, SERVING AS A CARRIER TO DELIVER THE POLLEN SPERM CELLS TO THE EGG CELL, COMPLETING THE MATING PROCESS AND ENABLING FERTILIZATION. FILAMENTOUS-ACTIN OR F-ACTIN IS A KEY CYTOSKELETAL COMPONENT WITHIN CELLS, WHICH PLAYS A CRUCIAL ROLE DURING POLLEN TUBE GROWTH. IT PROVIDES STRUCTURAL SUPPORT AND FACILITATES THE ELONGATION OF THE POLLEN TUBE TO NAVIGATE THROUGH THE FEMALE REPRODUCTIVE ORGANS, FOR SUCCESSFUL FERTILIZATION. WHILE THE ROLE OF F-ACTIN HAS BEEN EXTENSIVELY STUDIED IN NON-CROP SPECIES, RELATIVELY LITTLE IS KNOWN OF HOW F-ACTIN REGULATES POLLEN TUBE GROWTH IN AGRICULTURAL CROPS LIKE TOMATO. FURTHERMORE, TOMATOES ARE EXTENSIVELY CULTIVATED AND THEIR REPRODUCTION IS IMPAIRED DURING HIGH TEMPERATURE STRESS RESULTING IN DECREASED YIELD. OUR LABORATORY HAS SHOWN THAT ELEVATED TEMPERATURES SIGNIFICANTLY IMPAIRED POLLEN TUBE GROWTH AND INCREASED LEVELS OF REACTIVE OXYGEN SPECIES (ROS), A GROUP OF REACTIVE CHEMICALS THAT CAN DAMAGE CELLULAR MOLECULES. THEREFORE, THIS PROJECT SEEKS TO INVESTIGATE THE IMPACT OF ELEVATED TEMPERATURE ON POLLEN TUBE F-ACTIN DYNAMICS, WITH A SPECIFIC FOCUS ON UNRAVELING THE MOLECULAR AND CELLULAR MECHANISMS THROUGH WHICH ROS INFLUENCES F-ACTIN DYNAMICS DURING HEAT STRESS.TO ACHIEVE OUR GOALS, WE WILL GENERATE TRANSGENIC PLANTS THAT CAN BE USED TO VISUALIZE F-ACTIN AND ROS. WE WILL UTILIZE ADVANCED LIVE-CELL IMAGING FACILITIES THAT WILL ENABLE THE VISUALIZATION OF F-ACTIN, NEW INSIGHT INTO THE FUNCTIONS OF THE CYTOSKELETON IN REPRODUCTIVE CELLS OF AN IMPORTANT AGRICULTURAL SPECIES. THE GOAL OF THIS PROJECT IS TO BETTER UNDERSTAND HOW F-ACTIN ORGANIZATION AND DYNAMICS ARE AFFECTED BY HIGH TEMPERATURE AND INCREASED ROS LEVEL. WE BELIEVE THAT THE INSIGHTS GAINED FROM THIS PROJECT WILL BE FUNDAMENTAL IN UNDERSTANDING THE ROLE OF THE CYTOSKELETON DURING POLLEN TUBE GROWTH. THIS KNOWLEDGE WILL BE UTILIZED TO BRIDGE THE GAP IN UNDERSTANDING PLANT REPRODUCTION MECHANISM UNDER TEMPERATURE STRESS.