GENETIC-TRANSFORMATION OF THE APPLE SCION CULTIVAR DELICIOUS VIA AGROBACTERIUM-TUMEFACIENS

Transformed shoots of the major apple scion cultivar 'Delicious' (Malus x domestica Borkh.) were obtained by cocultivation with Agrobacterium tumefaciens carrying disarmed plasmids. The transformation efficiency was influenced by the type of plasmid and by the inoculation temperature. Initial selection involved a callus stage followed by shoot regeneration. Shoot regeneration occurred only in the dark. Shoots grew in the light and were rooted in the presence of 100 mg l(-1) kanamycin. Of the range of plasmids tested, the cointegrates pGV 3850::1103neo and pGV 3850::1103gus gave a higher frequency of transformation than the binary vector pGV 3111 x pKIWI. Elongation of transformed shoots was enhanced by culture in a mixture of the cytokinins 6(gamma-gamma-dimethylallylamino)purine and 6-benzyladenine. Up to 60% of the elongated shoots rooted in 100 mg l(-1) kanamycin. Transformation was indicated by kanamycin resistance, beta-glucuronidase assay, nopaline synthesis, and by integration of the T-DNA as judged by Southern analysis.