Body of Abstract: Sugarcane is a highly productive C4 crop and a prime feedstock for commercial production of table sugar and bioethanol. Upon flower induction vegetative growth ceases and sucrose that has accumulated in the stalks is re-mobilized for use in reproductive development. Flowering often leads to dehydration of the stalk tissues, which negatively affects stalk density, and compromises sugar extraction. Since sugarcane is vegetatively propagated for plantings, suppression of flowering will not require an altered agronomic practice while improving the biocontainment of the engineered crop.
Weed control in sugarcane fields is most critical early in the season prior to sugarcane canopy closure to maximize sugarcane biomass yield. Weeds can reduce sugarcane yields by competing for moisture, nutrients, and light during the growing season. Atrazine is the primary herbicide being applied in sugarcane despite its persistence in the environment and inferior safety profile. Sugarcane is susceptible to sulfonylureas and imidazolinones herbicides, which control many grasses and broadleaf weeds. Acetolactate synthase (ALS), is a key enzyme in the biosynthetic pathway of branched-chain amino acids, and a target for ALS-inhibiting herbicides including sulfonylureas and imidazolinones. In this study, a recombinant DNA construct for the expression of a mutated acetolactate synthase gene conferring herbicide resistance and for RNAi mediated co-suppression of multiple FT genes was introduced into sugarcane by biolistic gene transfer. Transgenic plants harboring this recombinant DNA construct were planted at the University of Florida Everglades Research and Education Center, Belle Glade, FL in randomized and replicated field plots for the evaluation of flowering time, transgene expression and target gene suppression, agronomic performance, and biomass yield. Data will be presented comparing the phenotypic performance and herbicide resistance of transgenic sugarcane lines and non-transformed wild-type control.