Effect of NaCl, glutathione and ascorbic acid on function of tonoplast vesicles isolated from barley leaves

The seedlings of two barley cultivars differing in salt sensitivity were treated with 300 mmol/L NaCl for 0, 2, 4, 6, and 8 days. The activities of H+-ATPase (EC 3.6.1.35) and H+-PPase (EC 3.6.1.1) associated with tonoplast vesicles isolated from leaves were assayed. H+-ATPase activity increased in the salt-tolerant cultivar during the first 4 days of NaCl stress, and decreased later. In the salt-sensitive cultivar, however, H+-ATPase activity decreased after NaCl treatment. Both GSH content and APX activity of barley seedling leaves in the two cultivars showed the same trends as H+-ATPase activity. There was a significantly positive correlation between H+-ATPase activity and APX activity and between H+-ATPase activity and GSH content, respectively Under salt stress, exogenous GSH or AsA stimulated the activities of H+-ATPase and H+-PPase in two cultivars, and diminished MDA content and electrolyte leakage in leaves of two cultivars.