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Lipid biosynthesis by chloroplasts from olive tree leaves
Author(s) -
Daza Luis M.,
Donaire Juan P.
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb06327.x
Subject(s) - galactolipids , chloroplast , biochemistry , biosynthesis , oleic acid , linolenic acid , stearic acid , linolenate , fatty acid , fatty acid synthesis , galactolipid , biology , chemistry , enzyme , linoleic acid , organic chemistry , gene
In vitro incubation of isolated chloroplasts from young olive tree leaves ( Olea europaea L. cv. Marteño) in acetate‐1‐ 14 C showed a high labelling of saturated fatty acids (palmitic + stearic) and, above all, of the monounsatured ones (oleic); the low biosynthetic rate of α‐linolenic acid being noteworthy. These fatty acids are mainly found as free ones, or incorporated in mono‐and diglyceride molecules. Phosphoand galactolipids, the most abundant acyl‐lipid components of chloroplast lamellae, showed low incorporation rates. The fatty acid synthesis by isolated chloroplasts depends on exogenous CoA, ATP, NADPH and, especially, on added ACP (acyl carrier protein) preparation from Escherichia coli , whereas it was strongly inhibited by Triton X‐100. In vivo experiments with acetate‐1‐ 14 C infiltration into young excised leaves showed a high labelling of chloroplast phospholipids, but a low 14 C incorporation into galactolipids, a remarkable feature because these latter are main components of chloroplast lamellae. The high biosynthetic rate of α‐linolenic acid is noteworthy and appears mainly linked to monogalactosyldiglycerides. Also the low incorporation of saturated fatty acids to neutral lipids is remarkable. The low in vitro synthesis of α‐linolenic acid in comparison with that of the in vivo conditions, suggests the existence of a cooperation between chloroplasts and other parts of the cell to carry out the synthesis of this compound.