Cerulenin-induced Changes in Lipid and Fatty Acid Content of Chloroplasts in Detached Greening Barley Leaves

Measurements were made of the monogalactosyl diglyceride, digalactosyl diglyceride, total phospholipid, and total fatty acid contents, the fatty acid compositions of the glycerolipids of plastids from detached barley leaves before and after 72 hours of greening in the presence or absence of the fatty acid biosynthesis inhibitor cerulenin. At the final stage of greening the incorporation of 1-(14)C-acetate into leaf tissue and that of U-(14)C-galactose into chloroplast galactolipids as well as the ultrastructure of chloroplasts were also studied. Cerulenin caused a marked reduction in the rate of accumulation of chloroplast lipids and fatty acids during the greening period. In addition, specific alterations were observed in the fatty acid composition of monogalactosyl diglyceride, phosphatidyl choline, and phosphatidyl inositol following cerulenin treatment, the possible reasons of which are discussed. 1-(14)C-acetate incorporation into leaf slices was only slightly reduced in cerulenin-treated leaves after 72 hours of greening, whereas nearly 3 times as much U-(14)C-galactose incorporated into chloroplast galactolipids as in the control. The chloroplasts of cerulenin-treated leaves displayed a marked membrane deficiency, probably due to the shortage of galactolipids.