Major improvements in biolistic transformation of suspension-cultured tobacco cells

Suspension cultures of the NT1 line of Nicotiana tabacum L. were used as a model system to study plant biolistic transformation, because of their uniformity, rapid growth, and ease of handling. The β-glucuronidase gene and the neomycin phosphotransferase genes were used to assay transient and stable transformation. Numerous factors were studied and optimized, such that the frequency of transformation was increased roughly 60-fold for transient transformants and 20-fold for stable transformants. Both biological parameters (the promoter used to drive gene expression, osmotic preconditioning and postbombardment handling of the cells) and physical parameters of the bombardment process (particle acceleration device and accelerator parameters) were tested. The factors that increased transformation rates the most were promoter strength, use of a helium-driven particle accelerator, and osmotic preconditioning of the cells.