Journal Article

Divinyl ether synthesis in garlic bulbs

Michael Stumpe, Jan-Gerrit Carsjens, Cornelia Göbel and Ivo Feussner

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 4, pages 907-915
Published in print March 2008 | ISSN: 0022-0957
Published online March 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern010

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Formation of 13-lipoxygenase-derived divinyl ethers has been described in garlic bulbs. Here, the identification of a cDNA from garlic is described, which encodes for an enzyme that corresponds to divinyl ether synthases (DES). The recombinant protein was expressed in Escherichia coli and shown to metabolize 13-hydroperoxy as well as 9-hydroperoxy linole(n)ic acid to etherole(n)ic and colnele(n)ic acid, respectively. This biochemical feature classifies it as a member of the CYP74C subfamily of cytochrome P-450 enzymes. Product analysis after incubation of purified recombinant enzyme and fatty acid hydroperoxides revealed the formation of a mixture of different cis/trans isomers with one isomer often dominant. RNA blot analyses showed a constitutive expression of DES transcripts predominant in below-ground organs of garlic. By exogenous application of salicylic acid and sorbitol, but not by methyljasmonate, the transcript was also induced in leaves. Whereas the prominent divinyl ether in garlic was the 13-lipoxygenase-derived etheroleic acid, analysis of transgenic Arabidopsis expressing garlic DES showed that 9-lipoxygenase-derived colnelenic acid dominated 24 h after wounding. These data indicate that the product pattern of this DES from garlic depends on the substrate availability and that the enzyme is the first member in the group of 9/13-DES.

Keywords: Allium sativum; cytochrome P-450; oxylipin metabolism; product specificity; substrate specificity

Journal Article.  4610 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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