Liposome-mediated delivery of tobacco mosaic virus RNA into tobacco protoplasts: A sensitive assay for monitoring liposome-protoplast interactions.

Tobacco mosaic virus (TMV) RNA was encapsulated in large, unilamellar phospholipid vesicles (liposomes), and the encapsulated TMV RNA was shown to be infectious when incubated with tobacco protoplasts under appropriate conditions. Maximal virus production in protoplasts was observed after their incubation with TMV RNA entrapped in phosphatidylserine/cholesterol liposomes. Infection was dependent on the presence of polyalcohols in the incubation mixture. Other parameters, such as the extent of vesicle binding, the cell-induced leakage of vesicle contents, and the degree of liposome toxicity were shown to be important in determining the efficiency of infectivity. Liposome-mediated delivery offers an efficient and reproducible method for introducing RNA into plant protoplasts.