Promoter deletions are essential for transformation of lettuce by the T-cyt gene: the phenotypes of transgenic plants

The Agrobacterium T- cyt gene was transferred into lettuce, Latuca sativa‘Saladin’ using a genotype-independent transformation procedure employing a supervirulent Agrobacterium tumefaciens strain carrying the binary vector pMOG23. Kanamycin-resistant shoots were initiated from inoculated explants only when sites were deleted within the T- cyt promoter. In culture, kanamycin-resistant shoots exhibited several phenotypes, including gall production, reduced internode length (dwarfism) and vitrification together with differences in rooting. Rooted, neomycin phosphotransferase (NPTII)-positive plants recovered from their abnormal phenotype and self pollinated to produce viable seed, following transfer to the glasshouse. Kanamycin-resistant lettuce plants exhibited increased cytokinin and chlorophyll contents compared to non-transformed plants, physiological features which could benefit long-term storage of this leafy vegetable.