Effect of Nickel on Membrane Integrity, Lipid Peroxidation and Fatty Acid Composition in Wheat Seedlings

The influence of 50 and 100 mu m Ni on membrane integrity, hydrogen peroxide content, lipid peroxidation as well as total fatty acid composition was studied in shoots and roots of wheat seedlings. In both organs, treatment with Ni led to significant increase in electrolyte leakage reflecting the metal-induced enhancement of membrane permeability. In the shoots, it was accompanied by significant increase in lipid peroxidation. Accumulation of hydrogen peroxide, more pronounced in the shoots, was also found in Ni-treated wheat. Exposure of wheat seedlings to Ni altered the total fatty acid composition, leading to decrease in their unsaturation, which was indicated by reduction in double bond index. In both organs, a significant decrease in linolenic acid (C18 : 3) content was observed. It was accompanied by increased linoleic (C18 : 2) and oleic (C18 : 1) acid contents in shoots and roots, respectively. In the shoots, parallel increase in palmitic acid (C16 : 0) and decrease in palmitoleic acid (C16 : 1) were found at the end of the experiment. Our results suggest that modification of fatty acid profile in Ni-treated wheat seedlings is partly related to lipid peroxidation and increased electrolyte leakage and may reflect damage of cells caused by the metal.