The potato is one of the most important calorie and protein sources in many developed and developing countries with total production yielding about 95 million tons of tubers worth about $ 24 billion dollars (1984 figures). The nutritional quality of the potato tuber protein, although relatively high, is, like for most plant proteins, deficient in certain essential amino acids, e.g. lysine and methionine. The expression of synthetic genes encoding proteins rich in essential amino acids, along with normal protein production within the tuber, may increase the overall nutritional quality of the potato as well as its aggregated value in the market especially for the food industry.

The last decade has seen growing awareness of the value of germplasm conservation.In vitro maintenance of germplasm can offer many advantages as a complement to field maintenance. The International Potato Center (CIP) has actively researched a wide range of methods for effectivein vitro maintenance in its large potato germplasm collection. This review describes the methodology applied by CIP and discusses new research now being undertaken to study the genetic stability of these storage methods.

The range of sophisticated techniques available in tissue culture is clearly a broad one. Some of these techniques are already having a direct and significant impact on potato production and their use is widespread. Other techniques are still at a developmental stage and they offer great potential for direct or indirect improvement of potato production. However, time will be needed before the possible benefits of these types of research are transferred to farmers’ fields.

This paper describes a reproducible method for the induction of in vitro potato tubers in a wide range of genotypes. These in vitro tubers could be induced in all genotypes tested and show striking similarity to field produced tubers. In vitro tubers may prove most useful as material for International germplasm distribution.

Introduction Tissue-culture techniques have been available now for a considerable time, and have enjoyed remarkable success as a means of propagating certain crop plants (e.g. potatoes, fruit trees, and certain brassicas), and ornamentals, (most notably orchids, ferns and bromeliads)36,37. As long ago as 1957 Merrill King25 published a paper reporting callus-induction in several species of cacti, but other reports since then have been rather few and far between. One recent reviewer of the horticultural application of plant tissue-culture techniques was obliged to report that ‘Cacti and succulents have received little attention although valued as ornamentals’39. However, recent work by Krulik28, Mauseth32,33, Johnson & Emino19 and others have shown that propagation of cacti and succulents by tissue-culture is feasible. This review is intended to summarize the progress made, and the advantages and potential drawbacks of this approach to propagation.