Involvement of Plasma Membrane Alterations in Cold Acclimation of Winter Rye Seedlings (Secale cereale L. cv Puma).

Using plasma membranes with high purity isolated from winter rye seedlings (Secale cereale L. cv Puma) by an aqueous two-polymer phase partition technique, lipid and protein changes were determined during the development of cold hardiness.The degree of fatty acid unsaturation and proportions of phospholipid classes changed only slightly during cold acclimation. A small change, however, was observed in sterol composition; beta-sitosterol increased gradually with a corresponding decrease in campesterol plus stigmasterol during cold acclimation. The phospholipid to protein ratio increased proportionally to the increase in cold hardiness. During the period of acclimation, the sterol to phospholipid ratio declined and was inversely related to the development of cold hardiness.A distinct difference between polypeptide components of nonacclimated and acclimated plasma membrane was observed on two-dimensional sodium dodecyl sulfate slab polyacrylamide gels. A change was also detected in glycopeptides. These results suggest that the plasma membrane is in a dynamic state during cold acclimation, changing in response to the development of cold hardiness.