Effects of NO-Status modification, heat hardening, and hydrogen peroxide on the activity of antioxidant enzymes in wheat seedlings

In order to determine the role of nitric oxide (NO) as a potential mediator in the induction of the antioxidant system, effects of the following treatments on the activity of antioxidant enzymes in roots of etiolated wheat (Triticum aestivum L.) seedlings were investigated: a scavenger of nitric oxide, 100 A mu M PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide); an inhibitor of the enzyme similar to animal NO synthase, 2 mM L-NAME (N-G-nitro-L-arginine methyl ester); an NO donor, 2 mM sodium nitroprusside (SNP); a 1-min heat hardening at 42A degrees C; and 10 mM hydrogen peroxide. The activities of superoxide dismutase (SOD), catalase, and guaiacol peroxidase increased under the influence of PTIO and L-NAME. A similar effect was caused by the treatment with SNP and heat hardening; the increased activities of SOD and catalase were observed under the influence of hydrogen peroxide. The pretreatment of intact seedling roots with PTIO and L-NAME did not significantly alter the influence of heat hardening and hydrogen peroxide on the activity of studied enzymes. It is concluded that both the increase and decrease in intracellular NO content can induce the enzymatic antioxidant system.