Liposomes bearing a quaternary ammonium detergent as an efficient vehicle for functional transfer of TMV-RNA into plant protoplasts

Liposomes composed of phosphatidylcholine (PC) and cholesterol, and bearing the hydroxyl form of the quaternary ammonium detergent diisobutylcresoxyethoxyethyldimethylbenzylammonium (DEBDA [OH^-]),were able to mediate functional transfer of tobacco mosaic virus RNA (TWV RNA) into tobacco and petunia protoplasts. Functional transfer of TMV RNA was revealed by the appearance of specific capsid polypeptides within 48 h after transfection. Transfer of TMV RNA with the aid of liposomes bearing the quaternary ammonium detergent was achieved using two alternative methods. TMV RNA was enclosed within large unilamellar liposomes composed of phosphatidylcholine and cholesterol, and bearing positively charged detergent. Incubation of such liposomes loaded with TMV RNA with plant protolasts resulted in transfer of the enclosed RNA into the recipient protoplasts. In addition, functional transfer was also achieved by a complex formed between liposomes bearing the detergent and externally added (non-enclosed) TMV RNA. Maximum transfection was obtained with a complex composed of lipids, a quaternary ammonium detergent and TMV RNA, at a ratio of 1:0.5:0.035 (w/w). Using such a complex, under optimal conditions, about 30% of the recipient protoplasts were transfected with TMV RNA. Liposomes lacking the quaternary ammonium detergent practically failed to transfer TMV RNA into tobacco or petunia protoplasts.