Transient foreign gene expression in polyethylene/glycol treated or electropulsated Eucalyptus gunnii protoplasts

Conditions for optimal transient gene expression of reporter genes (chloramphenicol acetyl transferase and β-glucuronidase) by polyethylene glycol or electrical treatment of Eucalyptus gunnii protoplasts derived from callus or cell suspension cultures were investigated. The effciency of electropermeabilisation depended on several factors including electrical parameters, pH and the source of protoplasts. Polyethylene glycol mediated DNA uptake was highly stimulated by heat shock pretreatment and was also more efficient than the electrical treatment. For both treatments the nature of the promoter associated with the reporter gene was very important. A promoter corresponding to a protein synthesis elongation factor gene was more effective than the classical promoter of the 35 S transcript from cauliflower mosaic virus.