Involvement of Nitric Oxide in the Implementation of the Stress-Protective Action of Cadaverine on Wheat Seedlings under Hyperthermia and Its Relations to Different Signal Messengers

The effect of exogenous cadaverine on heat resistance of etiolated wheat (Triticum aestivum L.) seedlings and possible roles of nitric oxide, hydrogen peroxide, and calcium ions in stress-protective effect of cadaverine were explored. Treatment of roots of intact seedlings with 1 mM cadaverine boosted their survival after a damage heating (10 min at 45 degrees C). Transitory elevations in the levels of nitric oxide and hydrogen peroxide were simultaneously observed in the seedlings' roots. The inhibitor of the oxidative pathway of nitric oxide synthesis (aminoguanidine) prevented the above cadaverine-induced accumulation of NO. The scavenger of H2O2 (dimethylthiourea) and the inhibitor of calcium influx to the cytosol (neomycin) also attenuated the effect of cadaverine on the NO content. These antagonists of NO and the modulators of calcium homeostasis partially reduced the augmentation of hydrogen peroxide caused by cadaverine. Treatment of the seedlings with dimethylthiourea, NO and calcium antagonists diminished the stress-protective effect afforded by exogenous cadaverine. The conclusion was drawn on the role of NO and its functional relations with ROS and Ca2+ in the processes of the cadaverine-induced adaptation of the wheat seedlings to high temperatures.