The potato is the world's fourth most important crop, grown in a wide range of climates and soil types. It is therefore important to have varieties or lines which are adapted to various types of stress, and the manipulation of growth physiological or characteristics through the techniques of tissue culture is of importance owing to the rapidity of obtaining results when compared with conventional methods of breeding. Where irrigation is used in cultivation it is frequently found that the salt content of the soil is raised to levels which become detrimental to yield, and therefore the selection of salt-tolerant or salt-adapted lines could be of value in the agricultural economy of hot-climate Countries. Tissue cultures of two commercial varieties of S. tuberosum,Desiree and Maris Piper, and of two wild species, S. acaule and S. have been established, including plantlets from nodal cuttings; callus derived from stem, cell tuber, and leaf; and suspension cultures from stem and tuber callus. been prepared and some properties investigated. Protoplasts have also Cultured tissues have been introduced into media containing a range of concentrations of sodium chloride by gradual adaptation to increasing concentration, and also by direct transfer to a range of concentrations, followed by selection of those tissues and cells capable of continued growth under the increased stress. Selection of salt-tolerant cell lines has also been made after the exposure of cultures to gamma-irradiation. The osmotic and toxic effects of higher salt concentrations have been considered, and the cellular structures of the normal and salt adapted cell lines have been compared by electron microscopy. The stability of the apparent tolerance to higher salt concentrations has been investigated through transfer to normal media growth bacl< fol 10wed by re-exposure to salt The ability of cell stress. suspensions, callus, and tuber discs to regenerate plantlets has been investigated.