Single-cells have for the first time been cultured by W. H. MUIR, A. C. HILDEBRANDT and A. J. RIKER (University of Wisconsin, Madison, 1954). They were obtained by shaking submerged callus cultures. A modified technique keeps the cultures in motion with the help of filtered air. The thus developed turbulence causes the separation of single cells from the callus.
L. BERGMANN (Botanisches Institut der Universität zu Köln, 1960) separated single cells from cultures by filtration. He transferred the resulting cell suspension onto agar culture dishes. This was the first cloning of plant cells, and it enabled plant physiology to catch up with microbiological techniques and questions.
Again were all biochemical analyses and experiments in which macromolecules, viruses or organelles had to be brought into the cells hindered by the cell wall that acted like a barrier. Single cells in culture dishes can regenerate into differentiated tissues, but the regeneration of suspended single cells fails almost always because the turbulence inhibits the generation of a stable bottom/top polarity.
A comparison of plant single-cell cultures and micro-organisms shows that the hope once placed in plant cell cultures did not carry out due to a serious difference between the two cell types. The volume of a plant cell happens to be 200,000 times as large as that of the average micro-organism and the resulting experimental problems like the rather slow metabolism and the rate of division calculated in days - and not minutes - have not yet been solved.
© Peter v. Sengbusch - b-online@botanik.uni-hamburg.de