title: Inhibition of lipoxygenase affects induction of both direct and indirect plant defences against herbivorous insects.
abstract: Herbivore-induced plant defences influence the behaviour of insects associated with the plant. For biting-chewing herbivores the octadecanoid signal-transduction pathway has been suggested to play a key role in induced plant defence. To test this hypothesis in our plant-herbivore-parasitoid tritrophic system, we used phenidone, an inhibitor of the enzyme lipoxygenase (LOX), that catalyses the initial step in the octadecanoid pathway. Phenidone treatment of Brussels sprouts plants reduced the accumulation of internal signalling compounds in the octadecanoid pathway downstream of the step catalysed by LOX, i.e. 12-oxo-phytodienoic acid (OPDA) and jasmonic acid. The attraction of Cotesia glomerata parasitoids to host-infested plants was significantly reduced by phenidone treatment. The three herbivores investigated, i.e. the specialists Plutella xylostella, Pieris brassicae and Pieris rapae, showed different oviposition preferences for intact and infested plants, and for two species their preference for either intact or infested plants was shown to be LOX dependent. Our results show that phenidone inhibits the LOX-dependent defence response of the plant and that this inhibition can influence the behaviour of members of the associated insect community.
authors.affiliation: Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands.
authors.forename: Maaike
authors.initials: M
authors.lastname: Bruinsma
authors.forename: Sarah
authors.initials: S
authors.lastname: van Broekhoven
authors.forename: Erik H
authors.initials: EH
authors.lastname: Poelman
authors.forename: Maarten A
authors.initials: MA
authors.lastname: Posthumus
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Müller
authors.forename: Joop J A
authors.initials: JJ
authors.lastname: van Loon
authors.forename: Marcel
authors.initials: M
authors.lastname: Dicke
mesh_terms: D000818:Animals; D001937:Brassica / Q000187:drug effects / Q000201:enzymology*; D002080:Butterflies / Q000502:physiology*; D005247:Feeding Behavior; D008084:Lipoxygenase / Q000378:metabolism* / Q000502:physiology; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D009036:Moths / Q000502:physiology*; D009822:Oils, Volatile / Q000737:chemistry / Q000378:metabolism; D010058:Oviposition; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D011720:Pyrazoles / Q000494:pharmacology*
chemical_list: D016859:Lipoxygenase Inhibitors; D009822:Oils, Volatile; D010940:Plant Proteins; D011720:Pyrazoles; D008084:Lipoxygenase; C015429:phenidone