Introduction of foreign DNA into walled plant cells via liposomes injected into the vacuole: a preliminary study

Plasmids containing the firefly luciferase reporter gene were introduced into tobacco and maize by electroporation. They were used to calibrate the performance characteristics of an Hamamatsu C1966 AVEC/VIM photonic camera-Leitz photomicroscope image processing system. Luciferin-dependent light emission was readily detected, on an individual cell basis, using the analytical photon counting mode of the Hamamatsu system. An efficient liposome-DNA encapsulation protocol was developed and used to introduce the firefly luciferase plasmid into walled cells of tobacco, maize, carrot and rice. This was achieved by pressure-injecting the liposomes (DNA encapsulated inside the vesicle) into the vacuole where they subsequently fused with the tonoplast, releasing the DNA into the cytoplasm. Analytical photon counting studies were conducted on injected cells to determine whether the DNA introduced in this way was expressed. To date all experiments have proved negative. Reasons for this lack of expression are discussed.