PLANT PHYSIOLOGY , Vol 114, Issue 4 1493-1500, Copyright © 1997 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Effect of Cold Acclimation on the Lipid Composition of the Inner and Outer Membrane of the Chloroplast Envelope Isolated from Rye Leaves
M. Uemura and P. L. Steponkus
Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, New York 14853
The lipid composition of the inner and outer membranes of the chloroplast
envelope isolated from winter rye (Secale cereale L. cv Puma) leaves was
characterized before and after cold acclimation. In nonacclimated leaves
the inner membrane contained high proportions of
monogalactosyldiacylglycerols (MGDG, 47.9 mol% of the total lipids) and
digalactosyldiacylglycerols (DGDG, 31.1 mol%) and a low proportion of
phosphatidylcholine (PC, 8.1 mol%). The outer membrane contained a similar
proportion of DGDG (30.0 mol%); however, the proportion of MGDG was much
lower (20.1 mol%) and the proportion of PC was much higher (31.5 mol%).
After 4 weeks of cold acclimation, the proportions of these lipid classes
were significantly altered in both of the inner and outer membranes. In the
inner membrane the proportion of MGDG decreased (from 47.9 to 38.4 mol%)
and the proportion of DGDG increased (from 31.1 to 39.3 mol%), with only a
slight change in the proportion of PC (from 8.1 to 8.8 mol%). In the outer
membrane MGDG decreased from 20.1 to 14.8 mol%, DGDG increased from 30.0 to
39.9 mol%, and PC decreased from 31.5 to 25.4 mol%. Thus, both before and
after cold acclimation, the proportion of MGDG was much higher in the inner
membrane than in the outer membrane. In contrast, the proportion of PC was
higher in the outer membrane than in the inner membrane. The relationship
between the lipid composition of the inner and outer membranes of the
chloroplast envelope and freeze-induced membrane lesions is discussed.
