Increased tolerance to oxidative stress in transgenic tobacco expressing a wheat oxalate oxidase gene via induction of antioxidant enzymes is mediated by H₂O₂

Abstract

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.

Accumulation, distribution, and physiological contribution of oxalic acid and other solutes in an alkali‐resistant forage plant, Kochia sieversiana, during adaptation to saline and alkaline conditions

“…Genetic engineering methods to express oxalate oxidase genes are a prospective research field. This technique has been successfully applied to transgenic plants such as soybean (Donaldson et al, 2001), tobacco (Berna and Bernier, 1997;Wan et al, 2009), tomato (Dessalegne et al, 1997), and sunflower (Hu et al, 2003), generating expression of an oxalate oxidase gene that has increased resistance to disease.…”

“…It catalyzes the degradation of oxalic acid into H 2 O 2 and CO 2 (Lane et al, 1993). H 2 O 2 plays an important role in peroxidase-catalyzed cross-linking reactions to reinforce the cell wall (Thordal-Christensen et al, 1997) and serves as a signal for the induction of defense mechanisms (Wan et al, 2009). It also induces the expression of corresponding gene responses to salt (Hurkman et al, 1994) and heavy metal-ions stresses (Berna and Bernier, 1999) to increase plant resistance.…”

Overexpression of Yeast Arabinono-1,4-Lactone Oxidase Gene (ALO) Increases Tolerance to Oxidative Stress and Al Toxicity in Transgenic Tobacco Plants

“…Photochemical quenching (q p ) which represents the fraction of open PSII reaction centers was calculated as (F m ′−F s )/(F m ′−F o ′) (Schreiber et al 1986). Ion leakage, malondialdehyde (MDA), and H 2 O 2 in leaf disks or root tips were measured as described previously (Wan et al 2009). For determination of H 2 O 2 , leaf disks or roots (0.5 g) were frozen in liquid nitrogen and ground to powder in a mortar with pestle, together with 5 ml of 5 % TCA and 0.15 g activated charcoal.…”

Enhanced Oxidative Stress Resistance through Activation of a Zinc Deficiency Transcription Factor inBrachypodium distachyon

“…For arsenite treatments, 100 mL of 5 mM arsenite (Sigma) was added directly to the pot at the roots using modified protocols (Dombrowski et al, 2008;Lehmann et al, 2012), and leaf tissue was extracted after 1 h of treatment. Paraquat and copper sulfate treatments used a modified version of existing leaf toxicity protocols (Zhang et al, 2006;Wan et al, 2009). For copper sulfate treatment, 7.5-to 10.2-cm leaves were harvested and submerged in a dilution of either 250 mM (gene expression stress assays) or 1 mM (nuclear localization and cell assays) under continuous light for either 48 h (gene expression assays) or 5 d (cell assays and nuclear localization).…”