THE EFFECT OF CYCLOHEXIMIDE ON THE CONTENT OF LIPIDS AND SOLUBLE-PROTEINS IN WINTER-WHEAT PLANTS DURING COLD-ACCLIMATION

The effect of cycloheximide on the content and composition of proteins and lipids in the leaves and crowns of wheat (Triticum aestivum L., cv. Mironovskaya 808) was studied, in relation to the development of cold hardiness during plant acclimation to low temperatures. Plants in the tillering stage were hardened at 2 degrees C for seven days in the light. The content of soluble proteins increased twofold during hardening, which correlated with the increased hardiness of the plant. Four ''new'' polypeptides appeared during hardening; they comprised about 10% of the total soluble proteins. Cycloheximide retarded the accumulation of soluble proteins, partly inhibited ''new'' protein biosynthesis, and completely suppressed the development of cold hardiness in plants. Cycloheximide also affected the composition and total content of lipids. The content of the polar lipids of membranes decreased threefold. The relative amounts of linoleic and linolenic acids decreased, while those of lauric, miristic, and palmitic acids increased. These changes were more pronounced in the crowns than in the leaves. The trend toward decreasing the polar lipid unsaturation was quite consistent. Cycloheximide was suggested to decrease the cold hardiness in plants through a direct blocking of protein biosynthesis and an indirect inhibition of lipid biosynthesis due to inactivation of the enzymes of lipid synthesis and dehydrogenation.