Lipid composition of plant mitochondria and of chloroplasts.

The mitochondrial lipids from avocado fruit, cauliflower buds, and potato tubers, and the lipids of chloroplasts isolated from avocado fruit and from cauliflower leaves were identified and the concentrations were determined. The lipid composition was compared with that of beef heart mitochondria. Phospholipids constituted 50-56% of total lipids in plant mitochondria while this fraction made up 90% of the lipids in beef heart mitochondria. In both cases the chief phospholipids were phosphatidylcholine and phosphatidylethanolamine. A characteristic feature of plant mitochondria was the presence of monogalactosyl- and digalactosyldiglyceride and of sulfolipid. Potato mitochondria differed from the particles of other species investigated by their higher content of galactolipids, sterol glycosides, and carotenoids and lower content of phospholipids and of total lipids in the lipidprotein complex. The galactolipid content was markedly higher in chloroplasts from all sources than in mitochondria. The spectrum of lipids in the phospholipid fraction differed more strikingly between chloroplasts of the leaf and the mitochondria of the bud of cauliflower than between the two organelles of the avocado mesocarp. The fatty acid distribution of individual lipids and of classes of lipids was also more similar in the two organelles of the fruit tissue than in the cauliflower material.