The pFF plasmids: cassettes utilising CaMV sequences for expression of foreign genes in plants.

A plant expression cassette was constructed using the cauliflower mosaic virus 35S 5' regulatory region with the enhancer duplicated and the 35S polyadenylation signal. Insertion of a polylinker between the transcription initiation and polyadenylation sites allows for easy cloning of genes. To test the usefulness of the cassette chimeric bacterial genes were prepared. The constructs were introduced into Nicotiana tabacum suspension culture cells by the particle bombardment process. Expression of the beta-glucuronidase reporter gene was verified by histochemical staining. Stable kanamycin and hygromycin resistant transgenic lines were obtained after introduction of chimeric genes encoding the enzymes neomycin phosphotransferase and hygromycin B phosphotransferase, respectively. The number of stable transformants was approximately 2% of the cells that transiently expressed the beta-glucuronidase reporter gene.