engleski

Peroxidase and proteins as salinity stress indicators in duckweed exposed to oil industry high density brines

Background and Purpose: Salinity stress is a widespread environmental problem. Saturated aqueous solutions of calcium chloride and calcium bromide and their mixtures are commonly used in the oil industry as high density brines. Certain amounts of these solutions could be released into the environment and endanger living organisms exposed to an increased concentration of salts. A test- plant duckweed Lemna minor L. was used to investigate the effect of these solutions on the enzyme peroxidase and on protein pattern as indicators of salinity stress. Material and Methods: Tested salt solutions were added in Hoagland's nutrient medium in the appropriate amounts to achieve concentrations of: 0.025, 0.05, 0.075 and 0.1 mol dm-3 of calcium chloride and/or calcium bromide. Guaiacol peroxidase activity was measured spectrophotometrically. Isoperoxidases and proteins of the control and treated plants were analysed electrophoretically. Results: Higher concentrations (0.075 and 0.1 mol dm?3) only slightly increased peroxidase activity but induced new isoperoxidases, three anodic and one cathodic . In plants treated with the highest concentration (0.1 mol dm-3) a new protein of 24-25 kDa was expressed while proteins of about 42, 30 and 19 kDa were more abundant than in the control. Conclusion: After an exposure of in vitro cultivated duckweed plants to high density brines in the concentrations of 0.075 and 0.1 mol dm-3 new isoperoxidases as well as salt-stress-induced proteins appeared suggesting these parameters as useful markers of salinity stress.

duckweed; Lemna minor L.; high density brines; calcium chloride; calcium bromide; salinity; peroxidase; stress-induced proteins

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