1Department of Biochemistry and Bioprocess Technology, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad -211007, India
Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida -201306, India
*Author for correspondence: Email: pankajkishor.mishra@sharda.ac.in
Online published on 6 November, 2013.
The present investigation was carried out to examine the induction of oxidative stress upon exposure to zinc. Increased levels of superoxide anion radical and hydrogen peroxide were detected in Helianthus annuus L. when seedlings were treated with increasing concentrations of ZnSO4.5H2O (500, 1000 and 2000 ìM) at different pH levels. Further, Zn2+ -treated seedlings showed elevated levels of lipid peroxides with a concomitant increase in the activities of antioxidant enzymes viz. ascorbate peroxidase (APX), guaiacol peroxidase (GPOD), catalase, superoxide dismutase (SOD) and glutathione reductase (GR) compared to controls as pH increased from 3.0 to 8.0. Though Zn2+ was readily absorbed by growing seedlings, its localization was greater in roots than shoots which was prominently influenced by H+ concentration. Overall, our results suggest that enzymes like SOD, peroxidases and GR serve as important components of antioxidative defense mechanism against Zn2+-induced oxidative stress in Helianthus annuus L. seedlings grown under acidic and alkaline medium.
Antioxidant, Helianthus annuus L, superoxide dismutase, oxidative stress
