Cadmium tolerance and antioxidative defenses in hairy roots of the cadmium hyperaccumulator, Thlaspi caerulescens.

Plant species capable of hyperaccumulating heavy metals are of considerable interest for phytoremediation and phytomining. This work aims to identify the role of antioxidative metabolism in heavy metal tolerance in the Cd hyperaccumulator, Thlaspi caerulescens. Hairy roots of T. caerulescens and the non-hyperaccumulator, Nicotiana tabacum (tobacco), were used to test the effects of high Cd environments. In the absence of Cd, endogenous activities of catalase were two to three orders of magnitude higher in T. caerulescens than in N. tabacum. T. caerulescens roots also contained significantly higher endogenous superoxide dismutase activity and glutathione concentrations. Exposure to 20 ppm (178 microM) Cd prevented growth of N. tabacum roots and increased hydrogen peroxide (H(2)O(2)) levels by a factor of five relative to cultures without Cd. In contrast, growth was maintained in T. caerulescens, and H(2)O(2) concentrations were controlled to low, nontoxic levels in association with a strong catalase induction response. Treatment of roots with the glutathione synthesis inhibitor, buthionine sulfoximine (BSO), exacerbated H(2)O(2) accumulation in Cd-treated N. tabacum, but had a relatively minor effect on H(2)O(2) levels and did not reduce Cd tolerance in T. caerulescens. Lipid peroxidation was increased by Cd treatment in both the hyperaccumulator and non-hyperaccumulator roots. This work demonstrates that metal-induced oxidative stress occurs in hyperaccumulator tissues even though growth is unaffected by the presence of heavy metals. It also suggests that superior antioxidative defenses, particularly catalase activity, may play an important role in the hyperaccumulator phenotype of T. caerulescens.

Boominathan R ，Doran PM 《BIOTECHNOLOGY AND BIOENGINEERING》

Plant responses to abiotic stresses: heavy metal-induced oxidative stress and protection by mycorrhization.

Schützendübel A ，Polle A 《JOURNAL OF EXPERIMENTAL BOTANY》

Does cadmium play a physiological role in the hyperaccumulator Thlaspi caerulescens?

Liu MQ ，Yanai J ，Jiang RF ，Zhang F ，McGrath SP ，Zhao FJ ... -  《CHEMOSPHERE》

Response of antioxidant enzymes, ascorbate and glutathione metabolism towards cadmium in hyperaccumulator and nonhyperaccumulator ecotypes of Sedum alfredii H.

Jin X ，Yang X ，Mahmood Q ，Islam E ，Liu D ，Li H ... -  《-》

Effects of cadmium on ultrastructure and antioxidative defense system in hyperaccumulator and non-hyperaccumulator ecotypes of Sedum alfredii Hance.

Jin X ，Yang X ，Islam E ，Liu D ，Mahmood Q ... -  《JOURNAL OF HAZARDOUS MATERIALS》