Lipid composition of tomato leaves as related to plant cold tolerance

We studied the effects of a low nonlethal temperature (6 degreesC) on the c ontent and composition of polar lipids and their fatty acids in tomato (Lyc opersicon esculentum Mill., cv. Sibirskie skorospelye) leaves. We demonstra ted that chilling resulted in a decrease in the content of total polar lipi ds per 1 mg protein. The content of lipids in chloroplast membranes (monoga lactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacyl glycerols, and phosphatidylglycerols) changed less substantially than the c ontent of phospholipids in other cell organelles and in the cytoplasm. Neut ral lipids comprised only 1% of total lipids, and their content also decrea sed after chilling. The relative amounts of unsaturated and saturated fatty acids in polar lipids were practically unchanged. The conclusion was drawn that the maintenance of a high level of chloroplast membrane lipids under low temperatures could play an important role in the survival of cold-toler ant plants.