SHRUB WILLOWS ARE A SHORT-ROTATION WOODY CROP GROWN ACCROSS THE NORTHEAST UNITED STATES FOR BIOENERGY. WILLOWS ARE UNIQUE IN THAT THEY ARE DIOECIOUS, HAVING SEPERATE MALE AND FEMALE PLANTS. THIS PROJECT SEEKS TO UNDERSTAND THE GENETICS UNDERLYING DIOECEY IN SHRUB WILLOWS, WHICH WILL BENEFIT CURRENT BREEDING EFFORTS TO DEVELOP SHRUB WILLOWS A A BIOENERGY CROP. EIGHT CANDIDATE GENES PREDICTED TO BE DIRECTLY REGULATING SEX HAVE BEEN IDENTIFIED, AND THESE WILL BE TESTED IN THE MODEL PLANT ARABIDOPSIS TO CONFIRM THEIR FUNCTION. POLYPLOID WILLOWS ARE COMMONLY USED IN THE SHRUB WILLOW BREEDING, AS THEY SHOW INCREASED YIELD, BUT ALSO OFTEN EXHIBIT A DISPROPORTIONATE NUMBER OF FEMALES. THIS PROJECT WILL USE SEQUENCING TECHNOLOGIES AND GENOME MAPPING TO DETERMINE THE NUMBER OF SEX CHROMOSOMES NECESSARY FOR MALES AND FEMALES IN TRIPLOID AND TETRAPLOID WILLOWS, WHICH WILL ENABLE BREEDERS TO MORE EFFECTIVELY DESIGN BREEDING SCHEMES. RARELY, WILLOWS WILL EXHIBIT MONOECEY, MALE AND FEMALE FLOWERS ONTHE SAME PLANT RATHER THAN SEPERATE PLANTS. THIS PROJECT SEEKS TO DETERMINE THE GENETIC BASIS OF THIS TRAIT BY PERFORMING SEQUENCING OF SELECT INDIVIDUALS IN FAMILIES GENERATED THROUGH CROSSES FROM A MONOECIOUS PLANT. THESE FAMILIES ALSO PRESENT A UNIQUE GENETIC RESOURCE, WHICH WE WILL USE TO MAP THE LOCATION OF GENES CONTROLLING VARIOUS TRAITS SUCH AS LEAF SIZE, SHAPE, AND GREENNESS, WHICH AFFECT PLANT YIELD. THE RESULTS FROM THIS PROJECT WILL NOT ONLY PROVIDE VALUABLE GENETIC AND BREEDING RESOURCES FOR SHRUB WILLOWS, BUT WILL ALSO BENEFIT THE BROADER PLANT BIOLOGY COMMUNITY, PARTICULARILY SCIENTISTS INTERESTED IN SEX DETERMINATION IN OTHER PLANT SPECIES.