engleski

Ecotoxicological effects of Aluminum and Zinc on growth and antioxidants in Lemna minor L.

Depending on their oxidation states, heavy metals can be highly reactive and consequently toxic to most organisms. The present study aimed to study the biological effects induced by accumulation of zinc, an essential micronutrient and aluminium, a nonessential element, in duckweed (Lemna minor L.). Relative growth rate of plants exposed to zinc (Zn) or aluminium (Al) sulfate (0.15 and 0.3 mM) for 15 days was more affected under zinc toxicity. High accumulation of both Al (maximum 2500 µ g g-1 dw) and Zn (maximum 5000 µ g g-1 dw) was accompanied by increase in dry weight under higher metal treatments. An antioxidant response was observed under both metal stresses with a large increase in superoxide dismutase and peroxidases. Contrary to that, catalase activity markedly declined in duckweed as a result of Zn treatment. Accordingly, lipid peroxidation, proline and ascorbate levels exhibited highest values in plants exposed to Zn while carotenoids level significantly decreased. These parameters were unaffected under Al stress, but H2O2 content displayed high values as under zinc stress. The results suggest induction of oxidative stress under both aluminium and zinc toxicity but also duckweeds capability to increase antioxidative defense. Additionally, Zn was found to be more toxic to duckweed than Al with concentrations applied. Due to high accumulation potential as well as tolerance through increased antioxidant capacity, duckweeds could be used for phytoremediation of moderately-level zinc and aluminum polluted waterbodies.

duckweeds; aluminium; zinc; antioxidant; metal toxicity; oxidative stress; antioxidative enzymes; lipid peroxidation; hydrogen peroxide

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