** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** HISTORICALLY, POLLEN DEVELOPMENT STUDIES UNDER HEAT STRESS ARE PERFORMED ACROSS SEVERAL DEVELOPMENTAL STAGES AND OCCASIONALLY THROUGH THE ENTIRE POLLEN FORMATION. HOWEVER, HIGH TEMPERATURE SPIKES HAVE BECOME MORE EXTREME AND WITH INCREASING FREQUENCY, AND IN MANY CASES WITH GREATER INTENSITY. THESE TEMPERATURE SPIKES IMPACT SINGLE DEVELOPMENTAL STAGES AND IN RARE OCCASIONS TWO OR MORE OF THEM. THEREFORE, IT IS NECESSARY TO ELUCIDATE THE MOST CRITICAL STAGES OF PLANT REPRODUCTION TO UNDERSTAND THE UNDERLYING MOLECULAR STRESS RESPONSES, AND TO USE THE KNOWLEDGE GENERATED WITH THE AIM OF DEVELOPING HEAT STRESS TOLERANT CROPS. HOW DEVELOPMENTALLY MALE GAMETOPHYTE IS PERTURBED BY HEAT STRESS HAS REMAINED LARGELY UNEXPLORED. THE GOAL OF THE PROPOSED WORK IS TO FILL A SIGNIFICANT GAP IN OUR UNDERSTANDING ON HOW HEAT STRESS PERTURBS DEVELOPMENTALLY EACH STAGE OF POLLEN FORMATION AND ULTIMATELY AFFECTS PRODUCTIVITY IN MAIZE. OUR PRELIMINARY RESULTS INDICATE A NEGATIVE EFFECT OF HEAT STRESS DURING THE MICROSPOROGENESIS-TO-MICROGAMETOGENESIS TRANSITION. WHETHER EACH POLLEN DEVELOPMENTAL STAGE RESPONDS SIMILARLY TO HEAT STRESS EPISODES REMAIN TO BE DETERMINED. WE HYPOTHESIZE THAT HEAT STRESS DOES NOT INDUCE THE SAME RESPONSES WHEN ONLY INDIVIDUAL DEVELOPMENTAL STAGES ARE EXPOSED TO HEAT STRESS. THE PROPOSED WORK AIMS TO IDENTIFY THE GENETIC AND EPIGENETIC FACTORS THAT NEED TO BE TIGHTLY REGULATED FOR NORMAL POLLEN DEVELOPMENT BUT ARE PERTURBED WHEN PLANTS EXPERIENCE HEAT STRESS. ELUCIDATING THE MOLECULAR BASIS OF POLLEN DEVELOPMENT UNDER STRESS WILL HELP FRAME THE MODEL NEEDED FOR IMPROVING THE RESILIENCE OF POLLEN VIABILITY AND HENCE YIELD WHEN PLANTS EXPERIENCE HEAT STRESS DURING THIS HIGHLY SENSITIVE DEVELOPMENTAL WINDOW.