Phospholipid synthesis in aging potato tuber tissue.

The effect of activation ("aging") of potato tuber slices on their phospholipid metabolism was investigated. Aged slices were incubated with (14)C labeled choline, ethanolamine, methionine, serine, and acetate. In all cases, the incorporation of radioactivity into the lipid fraction increased with the length of time the slices were aged. This incorporation was shown to be true synthesis and not exchange between precursors and existing phospholipids.The increased incorporation of labeled choline into lipids was mainly due to an increase in its uptake by the tissue, the presence of actidione during aging prevented this increased uptake. The increase in the incorporation of labeled acetate into lipids resulted from the development of a fatty acid synthetase during aging. In the case of ethanolamine, both its uptake into the tissue and its incorporation into the lipid fraction increased.The phospholipids formed from these precursors were identified by paper and thin-layer chromatography. The major compound formed from choline was lecithin, while phosphatidylethanolamine and a small amount of lecithin were formed from ethanolamine.