Thin-layer chromatography of phospholipids in Zea mays (L.) under oxygen deficit

Abstract

Environmental factors have a significant impact on the composition and properties of the lipids of plants. However, up to now, the lipid metabolism in plants under conditions of hypoxia or anoxia has not been studied as thoroughly as protein and carbohydrate metabolism. In our study, we analysed the dynamics of the concentration of certain classes of phospholipids in maize seedlings under the condition of short-term (24 hours) hypoxia and large concentrations of carbon dioxide. The samples were fixed using boiling isopropanol and extracted using a mixture of hexane:isopropanol (3:2). After purification from nonlipid impurities, lipids were evaporated on a rotary evaporator and dissolved in chloroform. Phospholipids were obtained by means of thin-layer chromatography on silica gel W plates and were then separated into classes on plates with silica gel 60G (Merk, Germany). The article demonstrates that the total concentration of phospholipids in plant cells subjected to hypoxia decreased to 82.4% and was almost two times lower in the carbon dioxide medium than it was for aerated plants. The study determined that phosphatidyl-choline (PC) and phosphatidylethanolamine (PE) were dominant in maize seedlings. The concentration of PC was 13.86±1.00, and the concentration of PE was 9.98±0.30 µg Р g^-1 of raw weight respectively which was up to 78% of all the phospholipids in the seedlings. We should note that the PC/PE ratio under oxygen deficit increased from 1.12 (for aerated seedlings) to 1.73 under hypoxia and 1.97 in the media with increased concentrations of carbon dioxide. At the same time, hypoxia was accompanied by a decrease in the concentration of phosphatidylserine and a slight increase in the concentration of phosphatidylglycerol. During the early hours of the experiment, we observed an increase in the concentration of phosphatidic acids in the seedlings as a result of activation of the corresponding phospholipases. The observed fluctuations in the concentrations of certain classes of phospholipids and the total concentration of phospholipids in the cells of maize seedlings were more significant at large concentrations of carbon dioxide rather than under hypoxia caused by a noble gas.

Our study confirmed the assumption that the ability of plants to adapt to the effect of adverse factors, including a lack of oxygen, is to a large degree determined by the changes that occur in the total concentration of phospholipids as well as the concentrations of certain types of phospholipids, including phosphatidic acids, which form as a result of their degradation.