Transformation of Montmorency sour cherry (Prunus cerasus L.) and Gisela 6 (P. cerasus × P. canescens) cherry rootstock mediated by Agrobacterium tumefaciens

Sour cherry (Prunus cerasus L.) scion cv. Montmorency and rootstock cv. Gisela 6 (P. cerasus × P. canescens) were transformed using Agrobacterium tumefaciens strain EHA105:pBISN1 carrying the neomycin phosphotransferase gene (nptII) and an intron interrupted ß-glucuronidase (GUS) reporter gene (gusA). Whole leaf explants were co-cultivated with A. tumefaciens, and selection and regeneration of transformed cells and shoots of both cultivars was carried out for 12 weeks on selection medium containing 50 mg l−1 kanamycin (Km) and 250 mg l−1 timentin. These media were [Quoirin and Lepoivre (Acta Hortic 78:437–442, 1977)] supplemented with 0.5 mg l−1 benzylaminopurine (BA) + 0.05 mg l−1 indole-3-butyric acid (IBA), and woody plant medium [Lloyd and McCown (Proc Int Plant Prop Soc 30:421–427, 1980)] containing 2.0 mg l−1 BA + 1.0 mg l−1 IBA for cv. Montmorency and cv. Gisela 6, respectively. Seven out of 226 (3.1%) explants of cv. Montmorency and five out of 152 (3.9%) explants of cv. Gisela 6 produced 30/39 GUS- and PCR-positive shoots from the cut midribs via an intermediate callus. Southern analysis of the GUS- and PCR-positive transformants confirmed stable integration of the transgenes with 1–3 copy numbers in the genomes of seven lines of cv. Montmorency and five of cv. Gisela 6. The selected transformants have a normal phenotype in vitro.