Liposome-mediated introduction of the chloramphenicol acetyl transferase (CAT) gene and its expression in tobacco protoplasts

The expression plasmid vector pUC8CaMVCAT, containing the chloramphenicol acetyl transferase (CAT) gene, was encapsulated in large unilamellar vesicles (LUV) and introduced into tobacco protoplasts derived from either cell suspension culture or leaf mesophyll. Treatment with liposomes took place in a buffer containing either NaCl or CaCl₂, but no polyethylene glycol. The presence of polylysine in the incubation buffer increased the adsorption of liposomes to protoplasts but decreased the efficiency of CAT gene expression. The expression of the introduced CAT gene could be monitored for at least seven days, following the treatment (about 25% acetylation at day 3 as well as at day 7). Plasmid DNA sequences could be detected, apparently unmodified, for at least nine days in the plant cells, though unintegrated in the host genome.