Microinjection: An Experimental Tool for Studying and Modifying Plant Cells

Abstract

The conviction that DNA is the genetic material of cells has its origins in a set of experiments in which purified DNA was transferred and expressed in bacterial cells. It is therefore no surprise that since these initial experiments with bacteria, methods of transferring DNA and other molecules into eukaryotic cells have been explored with varying degrees of success and usefulness. The most direct way of delivering a population of molecules into a cell or cell compartment is to microinject it mechanically (Celis, 1984; Celis et al., 1986). Techniques to accomplish this have been developed for frog oocytes (Gurdon et al., 1971; Kressman et al., 1978; Rusconi and Schaffner, 1981), insect embryos (Rubin and Spradling, 1982), animal egg cells (Brinster et al., 1985; Gordon et al., 1980; Hammer et al., 1985; Wagner et al., 1981) and mammalian somatic cells (Capecchi, 1980; Diacumakos, 1973; Graessman et al., 1980a, b). The anatomical organization of plant cells and the experimental difficulties associated with their manipulation in culture prevented a facile transposition of such techniques from animal to plant cells (Steinbiss et al., 1984). Fortunately, this situation is changing rapidly. It is now possible to microinject some plant cells and various protoplast types successfully (Crossway et al., 1986; Reich et al., 1986 a, b, c). It is the intent of this contribution to review these methodologies so that they can be extended, improved upon and become easily accessible to the community of plant cell and molecular biologists. Through this discussion we hope that the experimental advantages offered by microinjection become apparent.