In vitro recurrent selection of potato: production and characterization ofsalt tolerant cell lines and plants

A stable salt-tolerant potato cell line, able to grow on media containing 6 0-450 mM NaCl (i.e. low to high salinity) was selected. Callus grown on 120 or 150 mM NaCl showed higher fresh weights than the rest of the treatments . Replacing NaCl by KCl or Na2SO4 showed that reductions in fresh weight we re mainly due to the presence of Na+ ions. When PEG 6000 was added to the m edium instead of salt, the salt tolerant cell lines were unable to overcome the PEG-induced water stress. Whole plants, regenerated from salt tolerant callus, exhibited salt stress tolerance as evidenced by their higher fresh and dry weights when watered with 90 mM NaCl, and they also produced more tubers per plant under salt stress. Salt-tolerant plants differed phenotypi cally from control plants both in terms of leaf shape, tuber flesh and skin colour, which was reddish. In addition, DNA fingerprinting by RAPDs, with 70 different primers, confirmed that the salt tolerant regenerants also dif fered genotypically from the control, salt sensitive Kennebec potato plants from which they had been selected.