IMPACT OF EXCESS ZINC ON PHOTOSYNTHETIC PIGMENTS AND ANTIOXIDATIVE ENZYME ACTIVITIES OF RUDERAL VERBASCUM OLYMPICUM BOISS

Abstract

Verbascum olympicum Boiss. is dominated in disturbed areas of Uludağ Mountain/Turkey. It is a special species that is subject to phytoremediation due to its heavy metal accumulation, high biomass production and its ability to live in degraded areas. But, it is not known what its photosynthetic and antioxidative responses to high Zn concentrations that increased with anthropogenic activities such as mining, sewage sludge. Thus, in the present study we investigated photosynthetic pigments (chlorophyll a and b) and antioxidative enzymatic system of ruderal Verbascum olympicum grown in three different Zn levels (50, 250 and 500 µM) as zinc sulfate during 1, 3 and 10 days. The activity of antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX)] and photosynthetic pigment contents (chlorophyll a and b) was determined in the 8-week-old seedlings. Also, lipid peroxidation was measured as the amount of malondialdehyde (MDA) and, the cell membrane integrity and permeability was determined. Results were subjected to two-way ANOVA according to different Zn concentration treatments and exposed periods. It was determined an increase tendency up to 200 µM Zn treatment in antioxidative enzyme activities depending on increasing Zn concentrations and duration of exposure. This situation indicates that Verbascum olympicum has a strong antioxidative defense system for scavenging Zn-induced oxidative stress. But 500 µM Zn treatment had a destructive effect in photosynthetic pigment content and antioxidative enzymatic activities of V. olympicum. These results contribute to the understanding of survival success of Verbascum olympicum in degraded areas.