Transformation of a Strawberry Cultivar Using a Modified Regeneration Medium

Abstract

A protocol for shoot regeneration of strawberry (Fragaria ·ananassa Duch. 'Pajaro') leaf disks was developed. In Murashige and Skoog basal medium with 3% of sucrose (w/v), BA (1 mg·L -1 ), and 2,4-D (0.1 mg·L -1 ), 70% of the cultivated leaf explants regenerated plants. This regeneration system was used for genetic transformation of strawberry with Agrobacterium tumefaciens strain LBA 4404 carrying the binary vector plasmid pBI121 that contains the npt II (neomycin phosphotransferase) and uidA (s-D glucuronidase) genes. A transformation rate of 6.6%, calculated as the number of leaf disks able to regenerate kanamycin-resistant plants/total leaf disks infected, was obtained. The integration of both marker genes was evaluated in each transformed line by PCR (poly- merase chain reaction) amplifi cation of the npt II and uidA genes. High expression levels of the uidA gene were found in leaves, fl ower, and fruits of the transgenic lines. The protocol here reported may represent a way to conduct transformation research in strawberries. Chemical names used: benzyladenine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D)