Effect of Drought Stress on the Structure of Mitochondrial Membranes of Pisum sativum L. Pea Seedlings Epicotyls in the Presence of the Nitric Oxide (II) Donor

The changes of the structural characteristics of mitochondrial membranes isolated from the pea (Pisum sativum L.) seedlings epicotyls under the influence of the nitric oxide donor (TNIC-thio) under water deficiency conditions were studied. Low-temperature structural rearrangements, which are associated with the “crystal–liquid crystal” transition, for the lipid and near-protein regions of the mitochondrial membranes of the pea seedlings epicotyls of the control group and under drought stress conditions were observed. The microviscosity of both regions of the mitochondrial membranes under water deficiency conditions was higher than for the control. Pre-treatment of seeds with the nitric oxide (II) donor caused a shift of the thermo-induced structural transition toward higher temperatures, indicating an increase a crystallinity of the pea seedlings epicotyls mitochondrial membranes. An increase in membrane crystallinity may suggest enhanced plant resistance to water deficiency. The increase in the microviscosity of mitochondrial membranes pre-treated with TNIC-thio under water deficiency was less pronounced compared to seeds not treated with the NO donor. However, the fluidity of the lipid bilayer of pea seedlings epicotyls mitochondria was restored only partially and did not reach control values.