Biosynthesis of fatty acid derived aldehydes is induced upon mechanical wounding and its products show fungicidal activities in cucumber.
Fatty acid 9/13-hydroperoxide lyase (9/13-HPL) in cucumber is an enzyme that can cleave either 9- or 13-hydroperoxides of polyunsaturated fatty acids to form C9- or C6-aldehydes, respectively, as products. In order to reveal the physiological function of 9/13-HPL, its expression profiles were analyzed, and it was found that 9/13-HPL expression was developmentally regulated and high in the hypocotyls, female flowers and mature fruits. However, its transcript as well as its activity was only induced by mechanical wounding in mature leaves. To analyze the biosynthesis of HPL-derived aldehydes in more detail we isolated and characterized the yet missing 9-lipoxygenase (LOX) that is mainly expressed in hypocotyls, cotyledons and flowers and that may provide HPL with fatty acid 9-hydroperoxides as substrates. As in the case with C6-aldehydes in most plant species, C9-aldehydes were also formed rapidly after disruption of the tissues. C9-aldehydes had fungicidal activities against fungal pathogens, Botrytis cinerea and Fusarium oxysporum. Because the concentration needed to cause toxic effect on the pathogens was almost equivalent to that found in disrupted tissues, the C9-aldehydes thus formed could be helpful to sterilize the wounds since they are less volatile in comparison to C6-aldehydes.
Matsui
Kenji
K
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan. matsui@yamaguchi-u.ac.jp
Minami
Akari
A
Hornung
Ellen
E
Shibata
Hidetoshi
H
Kishimoto
Kyutaro
K
Ahnert
Volker
V
Kindl
Helmut
H
Kajiwara
Tadahiko
T
Feussner
Ivo
I
D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D001483:Base Sequence; D020171:Botrytis / Q000187:drug effects*; D018553:Cucumis sativus / Q000737:chemistry / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005670:Fusarium / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant; D006836:Hydro-Lyases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D000447:Aldehydes; D000935:Antifungal Agents; D005227:Fatty Acids; C443399:9-hydroperoxide lyase; D006836:Hydro-Lyases