Exogenous spermidine alters in different way membrane permeability and lipid peroxidation in water stressed barley leaves

In order to see whether polyamines will modify membrane functioning in the water stressed plants, barley (Hordeum vulgare) seedlings were treated with spermidine (Spd) prior to dehydration and then the stress-evoked changes in membrane permeability (i.e. in electrolyte leakage from leaves) and lipid peroxidation (indicated by modifications of the malondialdehyde (MDA) level, and of the lipoxygenase (LOX) activity) were followed. The Spd treatement lowered injury index in plants subjected to water deficit, although it slightly increased the stress-promoted LOX activity and increased the MDA level in the studied leaves. Presented results confirm that spermidine stabilizes plant membranes under water stress conditions. However, this effect does not seem to be associated with the Spd-induced modifications in the lipid peroxidation activities.