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Lutte chimique contre les champignons pathogènes des plantes : évaluation de la systémie phloémienne de nouvelles molécules à effet fongicide et d'activateurs de réactions de défense

Abstract : The development of fungicides that are translocated in the phloem to control root and vascular diseases has long been needed. Attempts to derivatize fungicides to make them phloem mobile have generally had the discouraging consequence of decreasing or suppressing their biological activity.
In this work, the first approach to this problem was similar to the successful strategy used in the development of acidic herbicides. The fungicide fenpiclonil was used as a model molecule because of the possibilities of adding a carboxyl group at various sites on the benzene or pyrrole rings. One of these derivatives, N-(1-carboxyethyl)-3-cyano-4-(2,3-dichlorophenyl)pyrrole exhibits a moderate phloem mobility and a fungicidal activity against a strain of Eutypa lata comparable to that of the parent compound.
The second strategy was to synthesize phloem mobile propesticides by adding an amino acid to various xenobiotics or natural compounds involved in plant defense. These conjugates, with an a-amino acid function, are translocated by plasma membrane permeases and clearly move in the phloem. However, the enzymes which may release the parent compounds may be more specific than the carrier system.
Finally, the capacity of Ricinus phloem to load salicylic acid (SA) was investigated for two motives: 1- SA is an important signal molecule involved in the acquired systemic resistance in plants, 2- in animal cells, SA is manipulated by a carrier system which also translocates drugs of larger size. SA strongly accumulates in the phloem and is ambimobile. In addition to the ion trap mechanism, some data rise the hypothesis of a pH dependent carrier system involved in SA phloem loading.
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Submitted on : Thursday, March 29, 2007 - 2:54:09 PM
Last modification on : Thursday, October 24, 2019 - 4:16:03 PM
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  • HAL Id : tel-00138898, version 2

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Françoise Rocher. Lutte chimique contre les champignons pathogènes des plantes : évaluation de la systémie phloémienne de nouvelles molécules à effet fongicide et d'activateurs de réactions de défense. Autre. Université de Poitiers, 2004. Français. ⟨tel-00138898v2⟩

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