Production of Transgenic Sweetpotato (Ipomoea batatas (L.) Lam.) Lines via Microprojectile Bombardment

Transformed sweetpotato plants were successfully produced from embryogenic calli induced from shoot apical meristem using by microprojectile bombardment. The pCAMBIA2301 vector used in the study contained â-glucuronidase (GUS) as a reporter and neomycin phosphotransferase II (NPTII) for selection. Transformed calli and plantlets were selected on medium containing kanamycin or G418, an analog of kanamycin. In selection of transformed event, G418 selection was more efficient than kanamycin to which sweetpotato callus was highly resistant. In each selection step, in order to determine GUS gene expression, a piece of calli or plantlets were histochemically assayed in X-gluc solution. The total time required from bombardment to the establishment of plants in soil was 5-6 months. By Southern blot analysis, three of independent transgenic plants were identified and multiple copies of transgenes were integrated into the sweetpotato genome. RT-PCR result showed all transgenic lines were successfully expressed at the mRNA level. Using leaf bleach assay, transgenic sweetpotato plants showed resistance to paromomycin, indicating that NPTII gene incorporated in the sweetpotato genome was expressed in sweetpotato plants.