<Emphasis Type="Italic">In vitro</Emphasis> selection of salt tolerant cell lines in <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.

Cell lines able to grow on media containing 50, 100, 150 or 200 mM NaCl were established from potato callus cultures by direct recurrent selection or gradual selection. In callus subjected to direct selection only small clusters of cells survived on medium with 150 or 200 mM NaCl, whereas on 100 mM small cell portions appear necrotic. When cell lines were obtained by successive subcultures on media with increased concentrations of NaCl, salt-tolerant calli were more compact and developed a greenish colour free from necrotic areas. The response of calli lines grown on media with NaCl was compared to control line. The NaCl-tolerant calli showed a decrease in relative growth rate and water content, with higher reductions in the 150 mM tolerant callus. Lipid peroxidation was increased in 50 mM and 100 mM NaCl-tolerant calli, while in 150 mM tolerant callus remained similar to 100 mM values. There was a significant increase in ascorbic acid content in 100 mM and 150 mM NaCl-tolerant calli as compared to the 50 mM, that was two-fold the value found in the control. Also, the contents of soluble and insoluble proteins increased in salt-tolerant lines. SDS-PAGE of soluble proteins showed the synthesis of specific polypeptides in the presence of NaCl in culture medium and the synthesis of a new polypeptide.