Liposome-mediated gene delivery into plant cells

Liposomes may offer several advantages as vectors for gene delivery into plant cells: (1) enhanced delivery of encapsulated DNA by membrane fusion, (2) protection of nucleic acids from nuclease activity, (3) targeting to specific cells, (4) delivery into a variety of cell types besides protoplasts by entry through plasmodesmata, (5) delivery of intact small organelles. Realization of these advantages calls for the construction of efficient liposomes, for appropriate fusion conditions and for an understanding of the nature of liposome-cell interactions. Various characteristics and techniques of the liposome-cell system are described (mode of delivery, liposome types and composition, and means of promoting delivery of liposome contents). Data of liposome-mediated delivery of various macromolecules into plant cells, with special reference to protoplasts, calli and pollen are reviewed. This includes data obtained by the use of fluorescent probes, radioactive-labelled DNA, viral nucleic acids and expression of plasmid-DNA. Structure and characteristics of plant surfaces and plasmodesmata are discussed with respect to DNA entry. It is suggested that liposome-mediated gene delivery into plant cells, and not only protoplasts, will be advantageous in certain specific tissues and situations.