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Wan X, Tan J, Lu S, Lin C, Hu Y, Guo Z: Increased tolerance to oxidative stress in transgenic tobacco expressing a wheat oxalate oxidase gene via induction of antioxidant enzymes is mediated by H2O2. Physiol Plant. 2009 May;136(1):30-44. Epub 2009 Feb 12.
Hydrogen peroxide (H (2) O (2)) plays a key role in the regulation of plant responses to various environmental stresses and modulates the expression of related genes including those encoding antioxidant enzymes. A wheat oxalate oxidase (OxO) gene was transformed and expressed in tobacco for production of H (2) O (2). The transgenic plants exhibited enhanced OxO activities and H (2) O (2) concentrations, which was blocked by inhibitors of OxO. The transgenic plants showed increased tolerance to methyl viologen (MV) or high light-induced oxidative stress in both short-time and long-time tests by measuring their maximal photochemical efficiency of PSII (F (v)/F (m)), ion leakage and malondialdehyde. Higher activities and transcripts of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) were observed in the transgenic plants compared to their wild-type controls under normal growth conditions. Pretreatments with inhibitors of OxO and scavenger of H (2) O (2) blocked the increase of tolerance to MV-induced or high light-induced oxidative stress, as well as the induction of antioxidant enzyme activities. Pretreatments with H (2) O (2) increased tolerance to oxidative stresses and antioxidant enzyme activities. It is suggested that H (2) O (2) produced by OxO in the transgenic tobacco plants triggers the signaling pathways to upregulate expressions of antioxidant enzyme genes, which in turn results in the increase of tolerance to MV-induced and high light-induced oxidative stresses. |
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