Changes Related to Salt Tolerance in Thylakoid Membranes of Photoauto- trophically Cultured Green Tobacco Cells

A line of cultured tobacco cells (Nicotiana tabacum cv. Samsun NN) was established that was able to grow photoautotrophically in a medium that contained 0.2 M NaCl or in a medium without NaCl. Thylakoid membranes of the NaCl-adapted cells had higher oxygen-evolving activi-ties, on the basis of chlorophyll, than those of unadapted cells. Furthermore, the oxygen-evolving activities of thylakoid membranes from NaCl-adapted cells were more tolerant to high concentra-tions of NaCl than those from unadapted cells. Glycinebetaine at 1 M protected the oxygen-evolving activity of thylakoid membranes from unadapted cells but not that from adapted cells. Examination of the dissociation of 23-kDa and 33-kDa polypeptides from the water-splitting complex of photosystem II at high concentrations of NaCl indicated that the affinity with which the 23-kDa polypeptide was bound to thylakoid membranes of salt-adapted cells had been altered. Key words: Nicotiana tabacum cv. Samsun NN — Oxygen-evolving activity — Photoautotrophic cultured cells — Salt tolerance — Thylakoid membranes. Salinity is a major barrier to the improvement of crop Wignarajah and Baker 1981). The actual concentrations of yields. Plant cells must be able to adjust their osmolarity to NaCl in glycophyte chloroplasts under saline condition