Hydrogen peroxide protects tobacco from oxidative stress by inducing a set of antioxidant enzymes

Abstract

Tolerance against oxidative stress generated by high light intensities or the catalase inhibitor aminotriazole (AT) was induced in intact tobacco plants by spraying them with hydrogen peroxide (H2O2). Stress tolerance was concomitant with an enhanced antioxidant status as reflected by higher activity and/or protein levels of catalase, ascorbate peroxidase, guaiacol peroxidases, and glutathione peroxidase, as well as an increased glutathione pool. The induced stress tolerance was dependent on the dose of H2O2 applied. Moderate doses of H2O2 enhanced the antioxidant status and induced stress tolerance, while higher concentrations caused oxidative stress and symptoms resembling a hypersensitive response. In stress-tolerant plants, induction of catalase was 1.5-fold, that of ascorbate peroxidase and glutathione peroxidase was 2-fold, and that of guaiacol peroxidases was approximately 3-fold. Stress resistance was monitored by measuring levels of malondialdehyde, an indicator of lipid peroxidation. The levels of malondialdehyde in all H2O2-treated plants exposed to subsequent high light or AT stress were similar to those of unstressed plants, whereas lipid peroxidation in H2O2-untreated plants stressed with either high light or AT was 1.5- or 2-fold higher, respectively. Although all stress factors caused increases in the levels of reduced glutathione, its levels were much higher in all H2O2-pretreated plants. Moreover, significant accumulation of oxidized glutathione was observed only in plants that were not pretreated with H2O2. Extending the AT stress period from 1 to 7 days resulted in death of tobacco plants that were not pretreated with H2O2, while all H2O2-pretreated plants remained little affected by the prolonged treatment. Thus, activation of the plant antioxidant system by H2O2 plays an important role in the induced tolerance against oxidative stress.

Environmental stress increases the entry of cytoplasmic organellar DNA into the nucleus in plants

“…In this transplastomic line (tp-gus), the reporter gus gene is expressed only when transferred to the nucleus-an events that is readily monitored by histochemical staining to detect the gus product, visualized as blue sectors in cells and tissues. Using this system in preliminary experiments, we investigated the effects of various stress conditions examined previously, including heat (21), salt (22), hydrogen peroxide (23), and paraquat (24), on plastid-to-nucleus DNA transfer. Heat stress was outstanding in increasing nuclear gus expression (Table 1, experiment 1).…”

Molecular mechanisms of desiccation tolerance in the resurrection glacial relic Haberlea rhodopensis

“…The leaves were then incubated in milli-Q water for 10 min, and the conductivity of the resultant solution was measured and expressed in mS. Chlorophyll was isolated by 80 % acetone extraction and its content was measured photometrically as reported [23]. Oxidative stress was assessed by measuring malondialdehyde levels with thiobarbituric acid as previously described [24]. Variable fluorescence (F v /F m ) was measured with a pulse amplitude modulated fluorimeter MINI-PAM (Walz, Effeltrich, Germany).…”

Hydrogen Peroxide-induced Cell Death in Arabidopsis: Transcriptional and Mutant Analysis Reveals a Role of an Oxoglutarate-dependent Dioxygenase Gene in the Cell Death Process

“…Four-week old plants were sprayed twice within one hour either with water or 20 mM AT for induction of PCD in the leaves as described (3). Seeds from the knockouts of the oxoglutarate-dependent dioxygenase (At3G13610.1) used in this study were obtained from the Arabidopsis Biological Resource Center (9), references SALK132418 (OG1) and SALK050137 (OG2).…”

“…Low doses of H 2 O 2 induce stress acclimation, while high doses trigger PCD (3,4). H 2 O 2 -induced PCD itself is essential for developmental processes and environmental responses, including aleurone cell death, hypersensitive response to pathogens, and allelopathic plantplant interactions (1,5,6).…”