Energy exchange and ultrastructure of plant cells under generation of nitric oxide

• Published in: Russian journal of plant physiology 2011, Vol.58 (1), p.100-108
• Main Authors: Rakhmatullina, D. F, Gordon, L. Kh, Ponomareva, A. A, Ogorodnikova, T. I, Alyab'ev, A. Yu, Iyudin, V. S, Obynochnyi, A. A
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; cell ultrastructure; heat generation; Life Sciences; mitochondria; nitric oxide; Plant Physiology; Plant Sciences; Research Papers; respiration; Triticum aestivum
• ISSN: 1021-4437; 1608-3407
• DOI: 10.1134/S1021443710061044

The effects of nitric oxide (NO) on oxygen consumption, heat generation, and cell ultrastructure were investigated in the seedlings of wheat (Triticum aestivum L.). The experiments were conducted with the excised roots of 5-day-old seedlings grown in the solution of CaCl₂ (2.5 × 10⁻⁴ M). The source of NO was NaNO₂ (5 × 10⁻³ M) where the roots were incubated. Production of NO was determined by means of EPR, respiration -- gasometrically, heat generation -- using a microcalorimeter. The results showed that NO was formed in the presence of NaNO₂. This was accompanied by a decrease in the respiration rate by about 30%, which lasted for 5-6 h. Apparently, NO inhibited mitochondrial oxidation because stimulation of oxygen consumption induced by 2,4-DNP was completely removed in the presence of NaNO₂. When the cells were affected by succinic acid in the presence of NaNO₂, respiration was strongly inhibited. The effects of succinic acid and NaNO₂ were negated by ascorbic acid. A decrease in the rate of respiration was accompanied by a reduction in heat generation. Moreover, the efflux of potassium ions to the root incubation medium was stimulated, which may point to changes in ionic membrane permeability. The observed changes in energy exchange were accompanied by disturbances in the cell ultrastructure. Nitric oxide induced a clarification of the mitochondrial matrix and a reduction in the number of cristae. It was concluded that NO excess in plant tissues brings about a deceleration of energy exchange, disturbance of the ultrastructural organization, and cell death.