Uptake and effects of lead and copper on three plant species in contaminated soils: Role of phytochelatin

Abstract

This study is aimed at the comparison between three plants, namely, Grass pea (Lathyrus sativus) , Alfalfa (Medicago sativa and Sainfoin (Onobrychis vicifolia) and their ability in absorbing heavy metals such as lead and copper for the process of phytoremediation. In addition, the knowledge of the plants ability in using detoxification mechanism phytochelatin (plant-metal chelating) was also studied. The experiment was carried out factorially as randomized complete design in research greenhouse at Agricultural and Natural Resources Faculty, Islamic Azad University, Karaj Branch, Karaj, Iran in 2009. Four levels of Pb(NO 3)2 (0, 200, 400 and 800 mg/kg) and four levels of Cu(SO 4)2 (0, 150, 300, 450 mg/kg) were used. The mean comparison showed that the maximum absorption and accumulation of lead among the three studied species were obtained in roots of grass pea. In spite of more absorption in grass pea than the two other species, the phytochelatin synthesized in the plant was the least and on the other hand. The measurement of 8-hydroxy-2-deoxyguanosine content which showed that the changes in cell nucleus under the toxicity of lead and copper was the most in grass pea, this amount of 8-hydroxy-2-deoxyguanosine content may be due to the lower phytochelatin content. In contrast, the species Sainfoin, in which detoxification mechanism was accompanied with the more phytochelatin synthesis than the other two species, had the least 8-hydroxy-2-deoxyguanosine content and thus, had minimum changes in cell nucleus under lead and copper toxicity.