Gas chromatographic analysis of fatty acids of maize phospholipids under various aeration conditions

Abstract

Lipids are crucial structural, repair, and functional component of plant cells. At the same time, phos-pholipids, relating to polar lipids, are the integral components of cell membranes determining together with proteins their structure and functions. Despite these facts, the number of works dedicated to oxygen deficit effect on lipid content and their fatty acid composition is very limited due to the complexity of research meth-ods of these plant cell components. The composition and dynamic pattern of fatty acids content in phospholip-ids of maize seedlings exposed to short-term hypoxia (3-24h) were investigated by gas-liquid chromatography method. Lipids were extracted after probe fixation by boiling isopropanol – the mixture of hexane: isopropanol (3:2). Phospholipids from lipid fraction were evolved by the method of thin layer chromatography. Hydrolysis of phospholipids and fatty acids methylation were conducted in vacuum-sealed ampoules under +100℃ for 2 hours. Gas chromatographic analysis revealed that palmitic (C16:0) and linoleic (C18:2) acids dominated in phospholipids of maize seedlings (27.39 and 54.78% of all acids respectively). In the case of oxygen deficit, within the first 3-6 hours, the content of dienoic C18:2 acid in phospholipids decreased and the unsaturation index fell from 1.15 (aeration) to 0.96. The reduction in unsaturated acids content in phospholipids of maize seedlings under hypoxia could be driven by phospholipids destruction or by the intensification of their fatty acids’ peroxidation as a result of lipoxygenases. By 24 hours of hypoxia, the content of C18:2 had been rising to the level of aerated plants probably because of synthesis enhancement. The UI of fatty acids was growing, however, it was lower than in aerated plants because of a decrease in palmitoleic (C16:1) acid from 7.74% to 0.92% and an increase in palmitic (C16:0) acid up to 29.17%. The research showed that changes in the fatty acid composition of maize phospholipids under oxygen deficit (hypoxia) become noticeable even during short-term (3-6h) expositions and not only during expositions that lasted several days, as was previously reported. Recovery of the unsaturation level of phospholipids fatty acids’ at the end of the experiment suggests that under short-term (less than 24h) oxygen deficit, mid-tolerant maize seedlings can stabilize the structure and the prop-erties of their biological membranes, which increases their adaptation properties.