Influence of environmental factors on the generation of nitric oxide in the roots of etiolated pea seedlings

The article studies the nitric oxide (NO) levels in the roots of etiolated seedlings of sowing peas (Pisum sativum L.) using the DAF-2DA fluorescent probe and fluorescent microscopy. Cross sections of roots of 100–150 µm (the site of a root which is 10–15 mm from the apex) are analyzed. It is shown that the level of NO in the roots after 24 h increased by more than a factor of 2 in the versions with NaNO2 and sodium nitroprusside. At feeding the seedlings with KNO3, a peak in the accumulation of NO in the roots (twofold increase) was observed after 30 min. Fertilizing seedlings with L-arginine (2 mM) increased the intensity of the fluorescence of the root sections by more than a factor of 2. The inoculation of seedlings of rhizobia (Rhizobium leguminosarum bv. viceae) contributed to the reduction of NO on the background of the control (H2O) and sodium nitroprusside and nitrogen compounds. Scavengers of NO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), hemoglobin) and inhibitors of nitrate reductase and animal NO synthase (sodium tungstate and aminoguanidine hydrochloride) reduced the level of NO in the roots. The results are discussed in relation to the role of NO in plants under the influence of biotic and abiotic factors.