Involvement of plasma-membrane NADPH oxidase in nickel-induced oxidative stress in roots of wheat seedlings

The roles of the plasma-membrane (PM) NADPH oxidase in nickel-induced oxidative stress were investigated in roots of wheat (Triticum durum D.) seedlings. Treatment with nickel resulted in significant increase in level of membrane lipid peroxidation, content of H2O2, the production rate of O2− and the activity of the PM NADPH oxidase in wheat roots. The effects caused by nickel were inhibited pronouncedly by pretreatments with three widely used NADPH oxidase inhibitors (diphenylene idonium, imidazole and pyridine). Moreover, the change patterns of the Ni-induced increase and inhibitor-caused decrease in these parameters were quite similar. These data suggest that the Ni-induced enhancements in levels of H2O2 and O2−, which appear to cause membrane lipid peroxidation, originate mainly from PM NADPH oxidase. A native in-gel assay also confirmed that PM NADPH oxidase participates in the Ni-induced production of reactive oxygen species in wheat. In addition, pharmacological experiments suggest that Ca2+ may be involved in the oxidative stress induced by nickel in wheat roots.