Involvement of hydrogen peroxide in heat shock- and cadmium-induced expression of ascorbate peroxidase and glutathione reductase in leaves of rice seedlings
2012
Chou, Ting-Shao | Chao, Yun-Yang | Kao, Ching Huei
Hydrogen peroxide (H₂O₂) is considered a signal molecule inducing cellular stress. Both heat shock (HS) and Cd can increase H₂O₂ content. We investigated the involvement of H₂O₂ in HS- and Cd-mediated changes in the expression of ascorbate peroxidase (APX) and glutathione reductase (GR) in leaves of rice seedlings. HS treatment increased the content of H₂O₂ before it increased activities of APX and GR in rice leaves. Moreover, HS-induced H₂O₂ production and APX and GR activities could be counteracted by the NADPH oxidase inhibitors dipehenylene iodonium (DPI) and imidazole (IMD). HS-induced OsAPX2 gene expression was associated with HS-induced APX activity but was not regulated by H₂O₂. Cd-increased H₂O₂ content and APX and GR activities were lower with than without HS. Cd did not increase the expression of OsAPX and OsGR without HS treatment. Cd increased H₂O₂ content by Cd before it increased APX and GR activities without HS. Treatment with DPI and IMD effectively inhibited Cd-induced H₂O₂ production and APX and GR activities. Moreover, the effects of DPI and IMD could be rescued with H₂O₂ treatment. H₂O₂ may be involved in the regulation of HS- and Cd-increased APX and GR activities in leaves of rice seedlings.
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