The effects of inhibitors on the incorporation of label from [2-14C]-acetate into the epicuticular wax classes witheven carbon numbers have been determined. They include the free fatty acids, the primary alcohols, thealdehydes, the ester acids and a newly identified wax class on barley spikes, the short chain esters. Dithiothreitol,which has no effect on β-diketone synthesis, inhibits decarboxylation of very long fatty acyl chains which areprecursors of the alkanes. Mercaptoethanol, which greatly stimulates wax synthesis at low concentrations andhas no effect on 13-diketone synthesis, blocks further elongation of fatty acyl precursors having 20 carbons athigher concentrations. A relatively small inhibition of decarboxylation was also observed with mercaptoethanol.Arsenite, which inhibits 13-diketone synthesis presumably by blocking the entrance of C16 precursors into the 13-diketone elongation mechanism, was also found to prevent the C20-C22 elongation step in the sequence leading tothe alkanes. Cyanide, which blocks 13-diketone synthesis by an unknown mechanism, greatly stimulated synthesisof the other wax classes. At higher concentrations a block in the elongation sequence leading to the alkanes wasalso apparent between C26-C28. These results are incorporated into a composite figure illustrating the biosyntheticrelationships among the wax classes. All identified chemical and genetic blocks have been included. The conclusionis reached that at least three elongation systems must be involved.
|Journal||Carlsberg Research Communications|
|Publication status||Published - 1978|
- Fatty acids
- Primary alcohols