JXB Advance Access published online on April 3, 2009
Journal of Experimental Botany, doi:10.1093/jxb/erp061
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© 2009 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
Composition of secondary alcohols, ketones, alkanediols, and ketols in Arabidopsis thaliana cuticular waxes
1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, V6T 1Z1, Canada
2Department of Botany, University of British Columbia, 6270 University Blvd, Vancouver, V6T 1Z4, Canada
* To whom correspondence should be addressed. E-mail: jetter{at}interchange.ubc.ca
Arabidopsis wax components containing secondary functional groups were examined (i) to test the biosynthetic relationship between secondary alcohols and ketols and (ii) to determine the regiospecificity and substrate preference of the enzyme involved in ketol biosynthesis. The stem wax of Arabidopsis wild type contained homologous series of C27 to C31 secondary alcohols (2.4 µg cm–2) and C28 to C30 ketones (6.0 µg cm–2) dominated by C29 homologues. In addition, compound classes containing two secondary functional groups were identified as C29 diols (
0.05 µg cm–2) and ketols (
0.16 µg cm–2). All four compound classes showed characteristic isomer distributions, with functional groups located between C-14 and C-16. In the mah1 mutant stem wax, diols and ketols could not be detected, while the amounts of secondary alcohols and ketones were drastically reduced. In two MAH1-overexpressing lines, equal amounts of C29 and C31 secondary alcohols were detected. Based on the comparison of homologue and isomer compositions between the different genotypes, it can be concluded that biosynthetic pathways lead from alkanes to secondary alcohols, and via ketones or diols to ketols. It seems plausible that MAH1 is the hydroxylase enzyme involved in all these conversions in Arabidopsis thaliana.
Key words: Chain lengths, cytochrome P450, fatty acid derivatives, gas chromatography, hydroxylation, MAH1, mass spectrometry, neutral lipids, plant surface composition, wax
Received 8 December 2008; Accepted 9 February 2009