Abstract: Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H₂O₂ in Sedum alfredii H. were examined. The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn²⁺ and/or 200 μmol/L Cd²⁺ increased linearly within 15 d. Contents of total S, glutathione (GSH) and H₂O₂ in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd²⁺ treatment than under Zn²⁺ treatment. However, reverse trends of H₂O₂ content in shoots were obtained, in which much higher H₂O₂ content was observed in Zn²⁺-treated shoots than in Cd²⁺-treated shoots. Similarly, the microscopic imaging of H₂O₂ accumulation in leaves using H₂O₂ probe technique showed that much higher H₂O₂ accumulation was observed in the Zn²⁺-treated leaf than in the Cd²⁺-treated one. These results suggest that there are different responses in the generation of H₂O₂ upon exposure to Zn²⁺ and Cd²⁺ for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H₂O₂ may play an important role in Zn hyperaccumulation in the leaves. Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H₂O₂.

Key words: Hydrogen peroxide (H₂O₂), Glutathione (GSH), Sedum alfredii Hance, Zinc (Zn), Cadmium (Cd), Hyperaccumulator

Please provide your name, email address and a comment

Your Name: Affili: E-Mail Address:

Comment (Please comment in English):


Verification Code(click to change a pic):