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Les composés secondaires soufrés des Allium : Rôle dans les systèmes de défense du poireau et actions sur la biologie des insectes

Abstract : Allium plant species such the leek, Allium porrum, produce sulphur secondary compounds. These compounds seem to be involved in Allium plants defence processes. Toxicity tests realised in confined atmosphere showed that sulphur compounds, thiosulfinates and disulfides, emitted by the leek, are very toxic against different insect species. One of these compounds, dimethyl disulfide (DMDS), kills insects by an inhibition of the mitochondrial respiratory chain complex IV (cytochrome oxydase). This DMDS-induced inhibition of complex IV subsequently decreased the intracellular ATP concentration, which thereby activated KATP channels mediating membrane hyperpolarisation and reduction of neuronal activity. Nevertheless, the larvae of leek moth, Acrolepiopsis assectella, specialist lepidoptera of Allium plant species were less susceptible to these sulphr compounds than the other tested species. This insect has developed unknowed specific mecanism to better tolerate sulphur compounds.
By repulsive and toxicity phenomena, sulphur compounds produced by Allium plants act in the field as constitutive direct defence against non specialist insects of Allium plants. This defence process could certainely explain why there is only a few number of insect species being able to consume leek leaves.
When they are strongly attacked by the leek moth, leek plants respond by an increase of non volatile sulphur compounds production which can leads to an increase of sulphur volatiles emission. This induced response has consequences on leek moth subsequent performances and thereby could be considered as an induced direct defence. Besides, the sulphur volatile compounds emitted by induced leeks are attractives for the leek moth natural enemy, the parasitic wasp, Diadromus pulchellus. In this way sulphur compounds produced by leek plants could be involved both in direct and indirect defence against the leek moth. In this model, complex indirect and direct defence processes coexist and stabilize the tritrophic interactions
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Contributor : Christine Besse <>
Submitted on : Monday, November 13, 2006 - 8:40:41 AM
Last modification on : Friday, June 7, 2019 - 10:55:59 AM

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S. Dugravot. Les composés secondaires soufrés des Allium : Rôle dans les systèmes de défense du poireau et actions sur la biologie des insectes. Ecologie, Environnement. Université François Rabelais - Tours, 2004. Français. ⟨tel-00113329⟩

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