engleski

Effects of different nitrogen and phosphorus concentration on antioxidative response of Lemna gibba plants to silver toxicity

Silver is non-essential heavy metal for plants known to cause oxidative stress. Several factors, such as the presence of nutrients, can affect the ability of plants to adequately respond to abiotic stress. The objective of this study was to investigate the effect of different nitrogen (N) and phosphorus (P) concentration on antioxidative response of plants to ionic colloidal silver (Ag). To provide insight, Lemna gibba plants were exposed to three N and P levels (100, 50 and 25%) for seven days and then to nominal 100 and 1000 μg/L Ag for 48h. Plants grown at lower N and P concentrations had significantly higher initial enzyme activities such as ascorbate peroxidase (APX), guaiacol peroxidase (GPOX) and superoxide dismutase (SOD) as well as elevated concentrations of ascorbic acid and total phenols. Increased antioxidative enzymes activities indicate oxidative stress-tolerance. Silver caused oxidative injury to L. gibba cells, evident from decreased protein and chlorophyll concentrations and increased concentrations of hydrogen peroxide (H2O2) and products of lipid peroxidation (TBARS). However, the production of H2O2 and TBARS as well as the degradation of proteins and pigments caused by Ag treatment was less pronounced in plants grown at lower N and P concentrations when compared to full strength medium. This could be explained by higher degree of protection from oxidative stress caused by Ag in plants grown at lower N and P supply. These results indicate that N and P supply, by modifying antioxidant activity in plants, can affect their tolerance to various kinds of stresses.

Lemna gibba; silver; nutrients; oxidative stress; antioxidative response

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