High-velocity microprojectiles for delivering nucleic acids into living cells

We report here a novel phenomenon, namely that nucleic acids can be delivered into plant cells using high-velocity microprojec-tiles. This research was conducted in the hope of circumventing some of the inherent limitations of existing methods for delivering DNA into plant cells1–6. After being accelerated, small tungsten particles (microprojectiles) pierce cell walls and membranes and enter intact plant cells without killing them. Microprojectiles were used to carry RNA or DNA into epidermal tissue of onion and these molecules were subsequently expressed genetically. This approach can therefore be used to study the transient expression of foreign genes in an intact tissue. It remains to be shown that smaller cell types, as are found in regenerable plant tissues, can be stably transformed by this method. If this proves possible, it would appear to provide a broadly applicable transformation mechanism capable of circumventing the host-range restrictions of Agrobacterium tumefaciens1, and the regeneration problems of protoplast transformation2–5.