PLASMA-MEMBRANE LIPID ALTERATIONS INDUCED BY NACL IN WINTER-WHEAT ROOTS

A highly enriched plasma membrane fraction was isolated by two phase partitioning from wheat roots (Triticum aestivum L. cv. Vivant) grown with and without 100 mM NaCl. The lipids of the plasma membrane fraction were extracted and characterized. Phosphatidylcholine and phosphatidylethanolamine were the major phospholipids with lesser amounts of phosphatidylinositol, phosphatidylglycerol, diphosphatidylglycerol, phosphatidic acid and phosphatidylserine. NaCl decreased the total phospholipids and the phosphatidylcholine portion of the plasma membranes. Salt treatment had no effect on total sterols and glycolipids, but the relative abundance of the free sterols was altered: cholesterol, stigmasterol and brassicasterol were significantly increased. Salt treatment resulted in an increase of the more planar/less planar ratio of the free sterols and in introduction of a double bond in the C-22 position in the side chain of stigmasterol and brassicasterol. The degree of fatty acid saturation of total phospholipids, phosphatidylcholine and phosphatidylethanolamine was increased after salt treatment. These lipid changes are discussed in relation to the salt tolerance mechanism.