Abstract
The effects of inhibitors on the incorporation of label from [2-14C]-acetate into the epicuticular wax classes with even carbon numbers have been determined. They include the free fatty acids, the primary alcohols, the aldehydes, 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 are precursors of the alkanes. Mercaptoethanol, which greatly stimulates wax synthesis at low concentrations and has no effect on β-diketone synthesis, blocks further elongation of fatty acyl precursors having 20 carbons at higher concentrations. A relatively small inhibition of decarboxylation was also observed with mercaptoethanol. Arsenite, which inhibits β-diketone synthesis presumably by blocking the entrance of C16 precursors into the β-diketone elongation mechanism, was also found to prevent the C20–C22 elongation step in the sequence leading to the alkanes. Cyanide, which blocks β-diketone synthesis by an unknown mechanism, greatly stimulated synthesis of the other wax classes. At higher concentrations a block in the elongation sequence leading to the alkanes was also apparent between C26–C28. These results are incorporated into a composite figure illustrating the biosynthetic relationships among the wax classes. All identified chemical and genetic blocks have been included. The conclusion is reached that at least three elongation systems must be involved.
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Abbreviations
- DTE:
-
1,4-dithioerythritol
- DTT:
-
1,4-dithiothreitol
- GLC:
-
gas liquid chromatography
- HEA:
-
hexane: diethylether: acetic acid
- ME:
-
2-mercaptoethanol
- TCA:
-
sodium trichloroacetate
- TLC:
-
thin layer chromatography
- u-l:
-
unknown lipid 1
- u-2:
-
unknown lipid 2
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Dalgaard Mikkelsen, J. The effects of inhibitors on the biosynthesis of the long chain lipids with even carbon numbers in barley spike epicuticular wax. Carlsberg Res. Commun. 43, 15–35 (1978). https://doi.org/10.1007/BF02906546
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DOI: https://doi.org/10.1007/BF02906546