** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** MANY CROPS, INCLUDING MAIZE, SORGHUM, AND MANY MILLETS, OCCUR IN A SUB-FAMILY OF GRASSES CALLED THE PANICOIDEAE. ALL PANICOIDS SHARE A FLORAL TRAIT THAT CONSTRAINS THEIR POTENTIAL PRODUCTIVITY. GRASS FLOWERS OCCUR IN STRUCTURES CALLED SPIKELETS. PANICOIDEAE SPIKELETS CONTAIN TWO FLOWERS, BUT USUALLY ONLY ONE FLOWER (THE UPPER FLOWER) IS FERTILE AND PRODUCES A GRAIN AFTER POLLINATION. THIS IS BECAUSE THE FLORAL ORGANS (CALLED CARPELS) THAT GO ON TO FORM THE GRAIN ARE SUPPRESSED IN LOWER FLOWERS, LEADING TO STERILE FLOWERS. THUS, POTENTIAL CROP PRODUCTIVITY IS CONSTRAINED BY CARPEL SUPPRESSION. IN THIS ERA OF GENOME ENGINEERING, CARPEL SUPPRESSION GENES COULD BE TRANSFORMATIVE TARGETS FOR GENOME EDITING AND YIELD IMPROVEMENT. HOWEVER, ONLY A FEW GENES ARE KNOWN TO REGULATE CARPEL SUPPRESSION IN MAIZE AND ITS RELATIVES. FURTHERMORE, HOW THESE GENES INTERACT IN PATHWAYS, AND WHETHER THESE GENES HAVE CONSERVED FUNCTIONS IN MANY GRASS SPECIES REMAINS UNKNOWN. HERE, WE WILL (1) EXPAND THE LIST OF GENES WITH KNOWN ROLES IN CARPEL SUPPRESSION, (2) DETERMINE HOW CARPEL SUPPRESSION GENES ARE ORDERED INTO GENETIC NETWORKS AND PATHWAYS IN MAIZE, AND (3) TEST THE HYPOTHESIS THAT A COMMON GENETIC MECHANISM REGULATES CARPEL SUPPRESSION IN THE PANICOIDEAE. TO ACHIEVE THESE OBJECTIVES, WE WILL USE STATE-OF-THE-ART METHODS IN GENETICS, GENOMICS, COMPUTER VISION, AND QUANTITATIVE PHENOTYPING.THIS PROJECT WILL PROVIDE FUNDAMENTAL KNOWLEDGE FOR ENSURING RESILIENT AND PROSPEROUS AGRICULTURAL SYSTEMS IN THE U.S. CARPEL SUPPRESSION GENES REPRESENT PROMISING TARGETS TO INCREASE YIELD IN MAIZE, AN IMPORTANT CROP IN THE U.S., AND IN ITS CLIMATE RESILIENT RELATIVES IN THE PANICOIDEAE. OUR RESULTS WILL REPRESENT AN IMPORTANT FIRST STEP IN DETERMINING THE GENETIC ARCHITECTURE OF CARPEL SUPPRESSION AND WILL ALLOW US TO EVALUATE THE POTENTIAL FOR THE GENES WE IDENTIFY TO AFFECT PRODUCTIVITY IN MAIZE AND THE MODEL PANICOID SETARIA VIRIDIS AT SMALL SCALES. GIVEN THE RELATIVE EASE OF GENOME EDITING IN MANY GRASSES, THE DISCOVERIES WE MAKE CAN BE TRANSLATED TO OTHER CROPS, TO BE RIGOROUSLY EVALUATED IN YIELD TRIALS. THERE IS A GROWING INTEREST WORLDWIDE IN CLIMATE- RESILIENT PANICOID CROPS, INCLUDING SORGHUM AND PROSO MILLET. HOWEVER, WHILE MANY MILLETS ARE DROUGHT, SALT AND HEAT TOLERANT, MOST ARE NOT HIGH-YIELDING, AND HAVE NOT BEEN SUBJECT TO THE INTENSIVE BREEDING THAT HAS SO DRAMATICALLY IMPROVED U.S. MAIZE YIELD IN THE 20TH CENTURY. SELECTIVE BREEDING, TOGETHER WITH TARGETED MODIFICATIONS TO KEY DEVELOPMENTAL GENES, SUCH AS CARPEL SUPPRESSION GENES, COULD DRAMATICALLY ACCELERATE YIELD IMPROVEMENTS. THUS, IDENTIFYING THE GENES THAT CONTROL PANICOID CROP PRODUCTIVITY COULD ACCELERATE THE PRODUCTION OF HIGH-YIELDING, CLIMATE-RESILIENT CROPS THAT WOULD ENHANCE THE LONG-TERM SUSTAINABILITY OF U.S. FOOD PRODUCTION SYSTEMS.