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The glutathione content in leaves significantly increased with increasing Cd concentrations, whereas in roots glutathione contents increased up to a concentration of 50 μM Cd and then decreased. | S. NAMDJOYAN, S. NAMDJOYAN, H. KERMANIAN Research Article Turk J Bot 36 (2012) 495-502 © TÜBİTAK doi:10.3906/bot-1110-34 Induction of phytochelatin and responses of antioxidants under cadmium stress in safflower (Carthamus tinctorius) seedlings Shahram NAMDJOYAN1,*, Shahrokh NAMDJOYAN2, Hossein KERMANIAN3 1 Department of Biology, Shahre Qods Branch, Islamic Azad University, Shahre Qods, Tehran - IRAN 2 Ministry of Agriculture, Land Affairs Organisation, Tehran - IRAN 3 Department of Pulp and Paper, Energy and New Technology Faculty, Zirab Rachis, Shahid Beheshti University, Tehran - IRAN Received: 31.10.2011 ● Accepted: 29.02.2012 Abstract: We investigated the role of antioxidant compounds (e.g., α-tocopherol, phytochelatins, glutathione, and other non-protein thiols) in the cadmium (Cd) tolerance of safflower (Carthamus tinctorius L. cv. Arak2811) seedlings exposed to different concentrations of Cd (0-100 μM) for a week. A concentration- and tissue- dependent response to Cd was observed. Increasing Cd supply markedly reduced the dry weight of roots. Plants accumulated a substantial amount of Cd, especially in the roots. Levels of α-tocopherol showed a significant increase with an increase in the concentration of Cd in leaves. Upon Cd exposure, α-tocopherol levels followed a similar pattern in the root tissue with no significant change as compared to the control. Cadmium exposure caused a significant increase in non-protein thiols and phytochelatin levels in roots, whereas non-protein thiols and phytochelatin levels were not affected in leaves. The glutathione content in leaves significantly increased with increasing Cd concentrations, whereas in roots glutathione contents increased up to a concentration of 50 μM Cd and then decreased. The results indicate that the non-protein thiol and phytochelatin biosynthesis induction in roots and enhanced level of α-tocopherol and glutathione in leaves may be involved in Cd tolerance and hyperaccumulation in .
