Herbicide-resistant sweet potato plants were produced through biolistics of embryogenic calli derived from shoot apical meristems. Plant materials were bombarded with the vectors containing the β-glucuronidase gene (gusA) and the herbicide-resistant gene (bar). Selection was carried out using phosphinothricin (PPT). Transformants were screened by the histochemical GUS and Chlorophenol Red assays. PCR and Southern-blot analyses indicated the presence of introduced bar gene in the genomic DNA of the transgenic plants. When sprayed with Basta, the transgenic sweet potato plants was tolerant to the herbicide. Hence, we report successful transformation of the bar gene conferring herbicide resistance to sweet potato.

We have used two aminoglycosides, G 418 and paromomycin, to develop a reliable selection system for nptll transgenic sweet-potato ( Ipomoea batatas (L.) Lam.). Embryogenic calli derived from shoot apical meristems were bombarded with gold particles coated with pCAMBIA2301, which contained the nptll and gusA genes. When compared on a kill curve that was based on calli proliferation and cell viability, G 413 -selection proved to be more efficient and had fewer escapes than kanamycin. These bombarded expiants were then selected on G 418 -containing media. The total time required from bombardment to plant establishment in soil was seven to nine months. Multiple copies of the transgene were integrated into the sweetpotato genome. Northern analysis confirmed transgene expression in the regenerated plants, and a paromomycin assay demonstrated that the nptll gene was functionally expressed in transformed sweetpotato. These molecular analyses and assays all showed that selection with G 418 and paromomycin is reliable. So far, we have produced 69 transgenic events with this system, at a transformation frequency of approx. 1.1%. That efficiency is based on the number of transgenic plants obtained and the amount of calli bombarded. Thus, this selection method that combines G 418 with paromomycin is now available for selecting nptll transgenic sweetpotato.

We have used two aminoglycosides, G418 and paromomycin, to develop a reliable selection system fornptll transgenic sweet-potato (Ipomoea batatas (L.) Lam.). Embryogenic calli derived from shoot apical meristems were bombarded with gold particles coated with pCAMBIA2301, which contained thenptll andgusA genes. When compared on a kill curve that was based on calli proliferation and cell viability, G413-selection proved to be more efficient and had fewer escapes than kanamycin. These bombarded expiants were then selected on G418-containing media. The total time required from bombardment to plant establishment in soil was seven to nine months. Multiple copies of the transgene were integrated into the sweetpotato genome. Northern analysis confirmed transgene expression in the regenerated plants, and a paromomycin assay demonstrated that thenptll gene was functionally expressed in transformed sweetpotato. These molecular analyses and assays all showed that selection with G418 and paromomycin is reliable. So far, we have produced 69 transgenic events with this system, at a transformation frequency of approx. 1.1%. That efficiency is based on the number of transgenic plants obtained and the amount of calli bombarded. Thus, this selection method that combines G418 with paromomycin is now available for selectingnptll transgenic sweetpotato.