Characterization and localization of plant phenolics likely involved in the pathogen resistance expressed by endomycorrhizal roots |
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Authors: | Jacques Grandmaison Gyorgy M. Olah Marie-Rose Van Calsteren Valentin Furlan |
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Affiliation: | (1) Plant Biochemistry Laboratory, Department of Biology, Concordia University, SGW Campus, 1455 De Maisonneuve Boulevard West, H3G 1M8 Montreal, Quebec, Canada;(2) Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Lavai, G1K 7P4 Sainte-Foy, Québec, Canada;(3) Centre de Recherche et de Développement sur les Aliments, Agriculture Canada, J2S 8E3 Saint-Hyacinthe, Québec, Canada;(4) Station de Recherches, Agriculture Canada, G1V 2J3 Sainte-Foy, Québec, Canada |
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Abstract: | Phytochemical characterization of the major phenolic compounds and their ultrastructural localization were carried out on onion roots (Allium cepa L.) colonized by two vesicular-arbuscular mycorrhizal (VAM) fungi: Glomus intraradix Schenck & Smith and G. versiforme (Karst.) Berch. Free and wall-bound forms of phenolic components were quantified in relation to the duration of symbiosis. Both ferulic and p-coumaric acids, as well as N-feruloyltyramine were identified as the major phenolic metabolites bound to the cell walls of VAM onion roots. Results from mycorrhized and control plants suggest the presence of a mechanism leading to the oxidative condensation of phenols, the latter process depending on the presence or absence of symbiosis. Bioassays reveal that N-feruloyltyramine induces the branching of hyphae and reduces total fungal development. The overall results lead us to suggest that the progressive binding of phenolic compounds in VAM roots is directly involved in the control of VAM endophytic establishment and development, as it gradually reduces the plasticity and elasticity of the symbiotic matrix. Phenolic compounds bound to cell walls could also be indirectly responsible for the resistance of VAM roots to pathogenic fungi, since they result in increased resistance by the cell wall to the action of digestive enzymes.Presented in part at the 31st Annual Meeting and Symposium of the Phytochemical Society of North America, Fort Collins, Colo., June 1991 |
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Keywords: | Vesicular-arbuscular mycorrhizae Phenolic metabolism Cinnamoyl amides Ultrastructural localization Disease resistance |
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