REGENERATION AND TRANSFORMATION SYSTEM IN EGYPTIAN SWEET POTATO (Ipomoea batatas Lam.) CULTIVARS

Genetic transformation is considered as one of the most favorable options for improvement of crop traits. In this study the regeneration frequency and transformation system were established on the Egyptian sweet potato (Ipomoea batatas (L.) Lam.) cv. Abees and Mabruka. The effect of different hormone combinations and type of explant on shoot regeneration was evaluated. The regeneration percentages from Abees and Mabruka cv. 26.3 and 13.3%, respectively were obtained on Murashige and Skoog MS basal salt mixture + 1.0 mg/l BA + 30.0 g/l sucrose + 2.2 g/l Phytagel with Abees cv. and the same media was used for cv. Mabruka with only cytokinin type different as 5.0 Kin and shoots were rooted on MS medium + 30 g/l sucrose and 2.2 g/l Phytagel. The Agrobacterium-mediated and microprojectile bombardement transformation system were successfully introducing the reporter gus and selectable bar marker genes in the sweet potato explants under pressure of 900 and 1100 psi and microcarrier travel distance (6 and 9 cm). Incorporation and expression of the gus and bar genes into sweet potato plants were confirmed using polymerase chain reaction (PCR) and GUS histochemical assay. Several factors were found to be important for regeneration and transformation in sweet potato. The most effective factors were plant genotype and the type of explants. Co-cultivation time and optical density of the Agrobacterium suspension were also critical for sweet potato transformation. This work is an attempt to open the door for further genetic improvement of sweet potato using important agronomic traits.