This study aimed to optimize factors for the efficient delivery of foreign genes into sweetpotato using Agrobacterium tumefaciens and develop transgenic plants. Disarmed Agrobacterium C58 carrying a binary vector pBI 121C2H with gusA, nptll, and the nutritional protein asp-l genes was used to cocultivate (4 days) petiole explants of the sweetpotato genotype P1318846-3. Pre-incubation of petioles for 3 days on MS medium with 2,4-D (0.2 mg·liter–1) before infection resulted in higher transformation. Putative transgenic shoots were obtained by transfer of petioles to MS medium with TDZ (0.2 mg·liter–1) and kanamycin (80 to 140 mg·liter–1). The PCR amplification of gusA, nptll, and asp-1 genes in the 37 putative transgenic shoots showed that six plants contained the three genes. However, none of these plants showed histochemical expression of the gusA gene. The introduced gene may have been methylated resulting in the lack of its expression. DNA blot hybridization studies are underway to verify the presence and integration of the transgenes.
GENETIC TRANSFORMATION AND REGENERATION OF TRANSGENIC SWEETPOTATO PLANTS.
