Pretreatment of lower H2O2 doses (0.05, 0.5 and 5 mM) for 24 h was able to dose-dependently attenuate lipid peroxidation in wheat seedling leaves mediated by further oxidative damage elicited by higher dose of H2O2 (150 mM for 6 h, with 0.5 mM H2O2 being the most effective concentrations. Further results illustrated that 0.5 mM H2O2 pretreatment triggered the biphasic production of H2O2 during a 24 h period. We also noticed that only peak I (0.25 h) rather than peak II (4 h) was approximately consistent with the enhancement of heme oxygenase (HO) activity, HO-1 gene expression. Meanwhile, enhanced superoxide dismutase (SOD) activity, Mn-SOD and Cu, Zn-SOD transcripts might be a potential source of peak I of endogenous H2O2. Further results confirmed that 0.5 mM H2O2 treatment for 0.5 h was able to upregulate HO gene expression, which was detected by enzyme activity determination, semi quantitative reverse transcription-polymerase chain reaction and western blotting. Meanwhile, the application of N,N’ dimethylthiourea, a trap for endogenous H2O2, not only blocked the upregulation of HO, but also reversed the corresponding oxidation attenuation. Together, the above results suggest that endogenous H2O2 production (peak I) plays a positive role in the induction of HO by enhancing its mRNA level and protein expression, thus leading to the acclimation to oxidative stress.
Chen XY, Ding X, Xu S, Wang R, Xuan W, Cao ZY, Chen J, Wu HH, Ye MB, Shen WB (2009). Endogenous hydrogen peroxide plays a positive role in the upregulation of heme oxygenase and acclimation to oxidative stress in wheat seedling leaves. J. Integr. Plant Biol. 51(10), 951-960.