EFFECTS OF BENZYLADENINE ON [U-C-14]ACETATE INCORPORATION INTO LIPIDS OF LEMNA-MINOR

The effect of a growth inhibiting concentration (22 muM) of benzyladenine (BA) on the incorporation of [U-C-14]acetate into the lipid fatty acids of Lemna minor fronds has been investigated. The incorporation of [U-C-14]acetate into phosphatidylcholine (PC), phosphatidylethanolamine (PE) and diacylgalactosylglycerol (DGG) fatty acids, especially alpha-linolenic acid, was stimulated in BA treated plants as compared with controls. The proportion of labelled alpha-linolenic acid in PC, PE and diacylglycerol of BA treated fronds increased during the period of incubation. These results seem to indicate that de novo synthesis and incorporation of labelled fatty acids into lipids of L. minor are not inhibited by a growth-inhibiting BA concentration. In BA-treated plants, the radioactivity incorporated into the alpha-linolenic acid of PC was always higher than that incorporated into the alpha-linolenic acid of DGG during 4 hr of labelling. This indicates that the desaturation of linoleic acid to alpha-linolenic acid occurs mainly with PC in Lemna minor but our results show that, DGG can, to a lesser extent, also achieve this desaturation.