THE EFFECTS OF NACL ON ANTIOXIDANT ENZYME-ACTIVITIES IN CALLUS-TISSUEOF SALT-TOLERANT AND SALT-SENSITIVE COTTON CULTIVARS (GOSSYPIUM-HIRSUTUM L)

To determine NaCl effects on callus growth and antioxidant activity, c allus of a salt-tolerant and a salt-sensitive cultivar of cotton was g rown on media amended with 0, 75, and 150 mM NaCl. Callus of the salt- tolerant cultivar, Acala 1517-8 8, grown at 150 mM NaCl, showed signif icant increases in superoxide dismutase, catalase, ascorbate peroxidas e, peroxidase and glutathione reductase activities compared to callus tissue grown at 0 mM NaCl. In contrast, callus tissue of the salt-sens itive cultivar, Deltapine 50, grown at 0, 75, and 150 mM NaCl, showed no difference in the activities of these enzymes. At the 150 mM NaCl t reatment, peroxidase was the only antioxidant enzyme from Deltapine 50 with an activity as high as that observed in Acala 1517-88. The NaCl- induced increase in the activity of these enzymes in Acala 1517-88 ind icates that callus tissue from the more salt-tolerant cultivar has a h igher capacity for scavenging and dismutating superoxide, an increased ability to decompose H2O2, and a more active ascorbate-glutathione cy cle when grown on media amended with NaCl.