Possible pathways of heat resistance induction in plant cells by exogenous nitrogen oxide

The mechanisms of exogenous nitrogen oxide (NO) influence on heat resistance of wheat coleoptiles have been studied. The treatment of plant cells with an NO donor (sodium nitroprusside) resulted in an increase in the generation of superoxide anion radicals (O 2 ·− ) after 10 min. The inhibitor of protein biosyn-thesis—cycloheximide—did not inhibit the O 2 ·− generation by coleoptiles induced by the NO donor, whereas the inhibitor of phosphatidic acid formation (butanol-1) inhibited it partially. Treatment of coleoptiles with calcium ionophore (A23187) or with an activator of the inositol cycle (inositol) compensated for the suppression effect of butanol-1 on NO-dependent O 2 ·− formation. Butanol-1 also leveled out the increase in the heat resistance of coleoptiles caused by the NO donor, whereas calcium ionophore and inositol almost completely removed the butanol-1 effect. The possible participation mechanisms of reactive oxygen species, phosphatidic acid, and calcium ions in the realization of NO physiological effects are discussed.