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3386267 
Journal Article 
Divinyl ether synthesis in garlic bulbs 
Stumpe, M; Carsjens, J; Goebel, C; Feussner, Ivo 
2008 
Yes 
Journal of Experimental Botany
ISSN: 0022-0957
EISSN: 1460-2431 
59 
4 
907-915 
English 
18326559 
WOS:000254293800016 
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. (copyright) 2008 The Author(s). 
Allium sativum; cytochrome P-450; oxylipin metabolism; product specificity; substrate specificity