**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** TWO AMARANTHUS SPECIES, WATERHEMP AND PALMER AMARANTH, ARE AMONG THE WORST AGRONOMIC WEEDS IN THE U.S. THEIR DIOECIOUS NATURE (PLANTS ARE EITHER MALE OR FEMALE) ENSURES OUTCROSSING, FOSTERING GREAT GENETIC DIVERSITY AND AN UNPRECEDENTED ABILITY TO EVOLVE RESISTANCES TO MULTIPLE HERBICIDES. IN NUMEROUS CASES, FARMERS HAVE RESORTED TO HAND WEEDING AS PART OF THEIR WATERHEMP/PALMER AMARANTH CONTROL PRACTICES. MY LONG-TERM GOAL IS TO EXPLOIT THE DIOECIOUS NATURE OF THESE TWO WEEDS TO DEVELOP A NOVEL GENETIC CONTROL STRATEGY BASED ON EMERGING GENE-DRIVE TECHNOLOGY. MY GROUP RECENTLY IDENTIFIED THE SEX-DETERMINING REGIONS OF THE GENOME FOR BOTH SPECIES, BUT THE CAUSAL GENES REMAIN UNKNOWN. I PROPOSE A COMPARATIVE GENOMICS APPROACH, UTILIZING OTHER DIOECIOUS AMARANTHUS SPECIES, TO IDENTIFY THE SPECIFIC GENES THAT ARE MOST LIKELY TO MEDIATE SEX DETERMINATION. SMALL-RNAS HAVE BEEN IMPLICATED AS PLAYING A ROLE IN SEX DETERMINATION IN OTHER DIOECIOUS SPECIES AND, BASED ON PRELIMINARY DATA, ALSO IN AMARANTHUS. THEREFORE, SRNAS ARE ALSO THE SUBJECT OF THE PROPOSED RESEARCH. ADDITIONALLY, THE STABILITY OF DIOECY IN WATERHEMP AND PALMER AMARANTH WILL BE EVALUATED USING AN ARTIFICIAL SELECTION EXPERIMENT. THE PROPOSED RESEARCH BUILDS ON SUBSTANTIAL PREVIOUS RESEARCH AND PRELIMINARY DATA TO FURTHER ADVANCE A TRULY NOVEL WEED CONTROL STRATEGY. THE PROPOSED RESEARCH ALSO DIRECTLY ADDRESSES PROGRAM AREA PRIORITY CODE A1112, PESTS AND BENEFICIAL SPECIES IN AGRICULTURAL PRODUCTION SYSTEMS: IT PROPOSES RESEARCH ON ASPECTS OF WEED BIOLOGY THAT IMPACT REPRODUCTIVE BIOLOGY AND IT WILL ADVANCE KNOWLEDGE OF INVASIVE OR ESTABLISHED PLANT PESTS... LEADING TO INNOVATIVE AND BIOLOGICALLY BASED STRATEGIES TO MANAGE PESTS.