Oxidative Stress Induction by Lead in Leaves of Radish (Raphanus sativus) Seedlings

Abstract

Oxidative stress was induced by lead acetate (Pb) in Raphanus sativus seedlings grown in a hydroponic system using sand as substrate. Thirty day old acclimated seeds were treated for 7 days with five Pb levels (0 as control, 100, 200, 500 and 1000 mg l-1). Parameters such as growth, oxidative damage markers (lipid peroxidation, protein oxidation and hydrogen peroxide contents) and enzymatic activities of catalase (CAT) and peroxidase (POD) were investigated. Lead concentration in plant tissues increased with increasing of Pb levels. Shoot fresh weight, chlorophyll and carotenoid concentration were significantly decreased at 100 mg l-1 Pb. Lipid peroxidation, protein oxidation and H2O2 levels were increased at 500 and 1000 mg l-1 Pb compared to control treatment, in shoots. Peroxidase activity showed a straight correlation with H2O2 concentration, whereas CAT activity decreased only in shoots. These changes in enzymatic and non-enzymatic antioxidants showed that the Pb exposition had a significant disturbance on Raphanus sativus plantlets and affect the biochemical and physiological processes.