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Rôle des extensines et leur glycosylation dans la défense racinaire

Abstract : Extensins are cell wall glycoproteins involved in various biological processes including plant protection. However, their mode of action in plant immunity response is not clearly established and remains to be elucidated. Extensins are able to strengthen the cell wall, one of the first cellular barriers against pathogens, through intra- and intermolecular cross-links. This cross-linking is catalysed by specific peroxidase enzymes and requires a correct conformation of extensins conferred by their glycan moiety. This PhD project aimed to investigate the impact of extensin glycosylation in root defence and to characterize, as a preliminary study, the peroxidases potentially involved in the extensin crosslinking in Arabidopsis thaliana. Through immunocytochemistry techniques on mutants impaired with extensin glycosylation, we have revealed that a modulation of extensin distribution occurs in A. thaliana root in response to elicitation with the bacterial peptide, flagellin 22. We have also showed that extensin arabinosylation plays a major role, although probably indirect, in the root colonization by the pathogen oomycete Phytophthora parasitica. We have therefore elaborated a model proposing to illustrate the importance of extensin arabinosylation in the cell wall organization and architecture, modulating pathogen adhesion on root cells and influencing in fine root colonization.
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Submitted on : Tuesday, October 1, 2019 - 9:24:32 AM
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Romain Castilleux. Rôle des extensines et leur glycosylation dans la défense racinaire. Biochimie, Biologie Moléculaire. Université de Rouen Normandie, 2017. Français. ⟨tel-02302069⟩



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