ANTIOXIDANT RESPONSE TO NACL STRESS IN A CONTROL AND AN NACL-TOLERANTCOTTON CELL-LINE GROWN IN THE PRESENCE OF PARAQUAT, BUTHIONINE SULFOXIMINE, AND EXOGENOUS GLUTATHIONE

A cotton (Gossypium hirsutum L.) control and NaCl-tolerant cell line ( cv Coker 312) were grown on media with or without NaCl in the presence or absence of paraquat, buthionine sulfoximine, and oxidized glutathi one. On medium with 150 mM NaCl the NaCl-tolerant cell line exhibited no reduction in growth, whereas a 96% reduction was observed in the co ntrol line. The NaCl-tolerant cell line that was grown on 150 mM NaCl exhibited significantly greater catalase (341%), peroxidase (319%), gl utathione reductase (287%), ascorbate peroxidase (450%), gamma-glutamy lcysteine synthetase (224%), and glutathione S-transferase (500%) acti vities than the intolerant control. The NaCl-tolerant cell line had a significantly lower dehydroascorbic acid/ascorbic acid ratio. Paraquat reduced growth by 20 and 53.7%, respectively, in the NaCl-tolerant an d control cell line. The NaCl-tolerant cell line also showed a slight tolerance to buthionine sulfoximine. In the buthionine sulfoximine exp eriments reduced glutathione restored growth in both cell lines, where as oxidized glutathione restored growth only in the NaCl-tolerant cell line. These data indicate that the NaCl-tolerant cell line exhibited a cross-tolerance to a variety of stress variables and had a more acti ve ascorbate-glutathione cycle.