The microdomains (rafts) of plasmalemma in the protection of the plant cell under oxidative stress.

The investigation of the lipid-protein microdomains of the plasmalemma isolated with the aid of the non-detergent technique in the zones of the sucrose density gradient after high-speed centrifugation from the tissue pieces of beet roots, which underwent oxidative stress, was conducted. The microdomains, whose lipid composition - according to the definition - allowed us to classify them as rafts, were studied. After the exposure to oxidative stress (100 mM hydrogen peroxide), the variations in the composition of membrane lipids bound up mainly with the elevations of the content of raft-forming lipids (sterols, sterol esters). Oxidative stress provoked redistribution in the composition of sterols, which led to an elevation in the content of campesterol and in the ratio of stigmasterol/sitosterol. Furthermore, the variations were registered in the content of phospholipids and phosphoglycerolipids, which are capable of stabilizing the lamellar structure of membranes. The results obtained allow one to assume that under the oxidative stress, variations in the composition of lipids in microdomains of the plasma membrane can take place. These variations may influence the functioning of the membranes, and the membranes may participate in the protection of the plant cell.