Journal of Lipid Research, Vol. 14, 664-671, November 1973
Copyright © 1973 by Lipid Research, Inc.
Lipid biosynthesis by isolated plastids from greening pea, Pisum sativum
R. A. Panter and N. K. Boardman
Division of Plant Industry, CSIRO, Canberra, A.C.T. 2601, Australia
Isolated etioplasts from 8-day-old dark-grown pea seedlings incorporated [1-14C]acetate into lipid at a relatively low rate. Plastids from seedlings that had been illuminated for at least 2 hr showed an enhanced incorporation provided the plastids were illuminated during incubation with the labeled acetate. Dark incubation or the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) decreased the acetate-incorporating activity of the developing chloroplasts to the level observed with etioplasts. Light had a marked effect on the type of fatty acid into which acetate was incorporated by the developing chloroplasts. Unsaturated fatty acids (mostly oleic acid) accounted for 60-80% of the incorporated label if the plastids were illuminated, but in the dark or in the presence of DCMU the unsaturated acids accounted for only 0-15% of the label incorporated into lipid. The effect of ATP on incorporation was dependent on the maturity of the chloroplasts; mature pea chloroplasts were inhibited by ATP, whereas in developing plastids there was a slight stimulation by ATP. Inhibition of acetate incorporation into lipid by DCMU appears to be due to inhibition of noncyclic phosphorylation. Incorporation was restored by reduced 2,3,5,6-tetramethylphenylenediamine, which restored phosphorylation, but not by reduced N,N,N',N'-tetramethylphenylenediamine.
Supplementary key words developing photosystems • desaturation • phosphatidylcholine • subcellular distribution • 3-(3,4-dichlorophenyl)-1,1-dimethylurea
Submitted on August 7, 1972
Revised on May 17, 1973
Accepted on July 17, 1973
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