METHOD: Content Assay CONDITIONS: Green House - 14h light at 18-20C or 2-4C METHOD NARR: Methods included the following procedures: preparation of the plasma membrane, protein concentration assay, lipid extraction, polar lipid factionation of total lipids, isolation and analysis of free sterols, glycolipids, phospholipids and fatty acid analysis. RESULTS NARR: Cold acclimation treatment resulted in an increased freeze tolerance from -4.5 to -9C inn tbr. Leaf plasma membrane lipids of cmm and tbr showed qualitative similarity but differed in quantitative respects. Acclimating cmm showed several plasma membrane lipid changes that did not occur in freezing-sensitive non-a in phospholipid content appears to be associated with increased freezing tolerance following acclimation in cmm. AUTHOR EXPLANATION: Comparing the plasma membrane from leaves of non-acclimated plants, a lower sterol-to-phospholipidportion of acylated steryl glycoside, and a lower proportion of free sterol were evident in cmm and may be related to greater freezing tolerance. These results suggest that the differences in freezing tolerance in the non to increase freezing tolerance during cold acclimation cannot be explained by the same biochemical and/or genetic mechanisms.