Vitamin E is essential for the tolerance of Arabidopsis thaliana to metal-induced oxidative stress. Plant Cell Environ

Laboratoire d'Ecophysiologie Moléculaire des Plantes, UMR 6191 CNRS-CEA-Université Aix-Marseille II, F-13108 Saint-Paul-lez-Durance, France.
Plant Cell and Environment (Impact Factor: 6.96). 03/2008; 31(2):244-57. DOI: 10.1111/j.1365-3040.2007.01755.x
Source: PubMed


Arabidopsis (Arabidopsis thaliana) plants were grown in a hydroponic culture system for 7 to 14 d in the absence or presence of 75 microM Cd or 75 microM Cu. The Cu treatment resulted in visual leaf symptoms, together with anthocyanin accumulation and loss of turgor. Pronounced lipid peroxidation, which was detected by autoluminescence imaging and malondialdehyde titration, was observed in Cu-treated leaves. The Cd treatment also resulted in loss of leaf pigments but lipid peroxidation and oxidative stress were less pronounced than in the leaves exposed to Cu. Analysis of low-molecular-weight chloroplast and cytosolic antioxidants (ascorbate, glutathione, tocopherols, carotenoids) and antioxidant enzymes (thiol-based reductases and peroxidases) revealed relatively few responses to metal exposure. However, there was a marked increase in vitamin E (alpha-tocopherol) in response to Cd and Cu treatments. Ascorbate increased significantly in Cu-exposed leaves. Other antioxidants either remained stable or decreased in response to metal stress. Transcripts encoding enzymes of the vitamin E biosynthetic pathway were increased in response to metal exposure. In particular, VTE2 mRNA was enhanced in Cu- and Cd-treated plants, while VTE5 and hydroxylpyruvate dioxygenase (HPPD) mRNAs were only up-regulated in Cd-treated plants. Consistent increases in HPPD transcripts and protein were observed. The vitamin E-deficient (vte1) mutant exhibited an enhanced sensitivity towards both metals relative to the wild-type (WT) control. Unlike the vte1 mutants, which showed enhanced lipid peroxidation and oxidative stress in the presence of Cu or Cd, the ascorbate-deficient (vtc2) mutant showed WT responses to metal exposure. Taken together, these results demonstrate that vitamin E plays a crucial role in the tolerance of Arabidopsis to oxidative stress induced by heavy metals such as Cu and Cd.

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Available from: Pascal Rey, Nov 21, 2014
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    • "Furthermore, ethylene insensitive ein3-1 mutants showed a delayed increase in α-tocopherol during water stress (Cela et al., 2009). This antioxidant compound was shown to be essential for the tolerance of A. thaliana plants to metal-induced oxidative stress (Collin et al., 2008). Therefore, the interaction between ethylene and the antioxidative defense network mounted during metal exposure can ultimately affect responses leading to sensitivity or tolerance and deserves further investigation. "
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    • "Considering the particular heavy metal ion added, the weakest, but nonetheless observable response occurred for Cd 2+ . This result is compatible with other results, which show that exposure to Cd 2+ did not lead to pronounced oxidative stress, as well as with observations made by others (Collin et al., 2008;Stoiber et al., 2011). The strong response to Cu 2+ is easy to understand, as this metal induces oxidative stress. "
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    • "For immunodetection of aconitase (Bernard et al., 2009) and PsaA (Agrisera), horseradish peroxidase-conjugated secondary antibodies and chemiluminescence were used. Autoluminescence imaging of lipid peroxidation was performed as in Collin et al. (2008). "

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