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 'S aladin' using a genotype-independent transformation procedure employing a s upervirulent Agrobacterium tumefaciens strain carrying the binary vector pM OG23. Kanamycin-resistant shoots were initiated from inoculated explants on ly 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 differe nces in rooting. Rooted, neomycin phosphotransferase (NPTII)-positive plant s recovered from their abnormal phenotype and self pollinated to produce vi able seed, following transfer to the glasshouse. Kanamycin-resistant lettuc e plants exhibited increased cytokinin and chlorophyll contents compared to non-transformed plants, physiological features which could benefit long-te rm storage of this leafy vegetable. (C) 1999 Annals of Botany Company.