Introduction

The ultimate objectives of any scientific investigation are twofold–to increase understanding, and to create opportunities for the application of the new knowledge, ostensibly in the service of man. The two objectives may not often be consciously connected in the minds of the investigators, but history and experience have demonstrated that new information always stimulates a drive towards practical application. This is already beginning to be true for plant cell biology through the directed manipulation of plant cells grown in culture.

As is described in chapter 15, it has been possible to culture organs, tissues and cells of higher plants under aseptic conditions for many years. These techniques, developed largely through assiduous application of the trial-and-error approach, are now becoming highly sophisticated and have already yielded information of great value to our understanding of cellular processes, particularly the cell cycle. In recent years, it has become possible to remove the walls from plant cells by enzymatic procedures, yielding naked protoplasts, some of which remain viable and may be propagated further (chapter 16).

The exploitation of cell and protoplast culture techniques for purely scientific purposes is still in its infancy, but already the methods have been used commercially for the propagation of valuable stock plants, and for the propagation of virus-free plants from virus-infected stocks. What makes cultured cells and protoplasts so exciting from the practical viewpoint, however, is the potential they appear to offer for artificial genetic manipulation. It is too early, yet, to say whether protoplast fusion or gene transfers (chapter 17) will yield new and revolutionary varieties of crop plants—the prospect does exist however, and a consideration of these matters seems a fitting note on which to conclude our coverage of the molecular biology of plant cells.