Protective effect of inhibitors of succinate dehydrogenase on wheat seedlings during osmotic stress

The effect of malonate and sedaxane, a compound with the fungicidal effect which act as succinate dehydrogenase inhibitors, on the resistance of etiolated wheat seedlings (Triticum aestivum L.) to osmotic stress caused by 12% PEG 6000 solution, was studied. The presowing treatment of seeds with 0.3 mM sedaxane solution significantly reduced the inhibitory effect of osmotic stress on seedling growth. The protective effect of 10 mM malonate was significant when it was added to the incubation medium of the roots; the effect of preseeding treatment with malonate was less significant. Unlike malonate, malate had no positive effect on seedling growth under osmotic stress. The activity of succinate dehydrogenase and the hydrogen peroxide content decreased in seedlings after the treatment of roots with malonate and sedaxane. Pretreatment with sedaxane and the addition of malonate to the incubation medium of roots prevented the accumulation of a lipid peroxidation product, malondialdehyde, which is caused by osmotic stress, and increased peroxidase activity. It was concluded that the stress-protective effect of sedaxane and malonate on wheat seedlings might be due to the inhibition of succinate dehydrogenase-dependent formation of reactive oxygen species and the prevention of oxidative cell damage.