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Dernière mise à jour : Mai 2018

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Institut Sophia Agrobiotech

UMR INRA - Univ. Nice Sophia Antipolis - Cnrs

http://www.paca.inra.fr/institut-sophia-agrobiotech_eng/

Aggregation molecular patterns in Phytophthora parasitica zoospores

Vendredi 21 juin à 14:00 - Sophia Antipolis - Inra PACA - Salle A010

Séminaire scientifique
Dans le cadre de l'animation scientifique de l'Institut Sophia Agrobiotech, Vendredi 21 Juin à 14h, salle A10; Ilaria Bassani, postdoc dans l'équipe IPO, nous présentera ses travaux.

Abstract

Within Oomycetes, Phytophthora genus includes some of the most damaging plant pathogens. They are eukaryotic filamentous microorganisms that spread in soil water (or hydroponic systems) as unicellular and biflagellate zoospores. Zoospores perceive plants’ signals through detection of chemical gradients (chemotaxis) and ionic fields (electrotaxis). They also produce signals to attract other zoospores, leading to in vitro aggregation (autotaxis) or to biofilm formation on plant surface. The mechanisms underlying intercellular communication and consequent attraction, adhesion and multicellular development are unknown.
Recent studies conducted in our labs demonstrated that in P. parasitica the perception of a K+ gradient induced coordinate motion and rapid aggregation, as result of a succession of negative chemotaxis and bioconvection.
Using this model, we combined RNAseq analysis with live cell imaging and ultrastructural microscopy to propose a first definition of molecular mechanisms involved in signal perception and transduction, leading to oomycetes collective movement and aggregation.
Firstly, the RNAseq analysis defined the transcriptome of zoospores freely swimming in water, to identify sequences related to motion, perception, adhesion and pathogenesis.
Moreover, it revealed that the K+ gradient induced significant upregulation (up to 30-fold) of gene expression for pathogenesis, vesicular trafficking, transcription factors and pH homeostasis. Enzyme kinetics and pH imaging data converged toward the hypothesis of an association between membrane-bound/cytosolic upregulated enzymes playing a core role on pH balance and consequently on collective motion and aggregation. Finally, ultrastructural analyses showed the accumulation of an intercellular filamentous matrix, likely comprising fibronectin-like and cadherin-like proteins.
This study will help us raising the first molecular model of the origin of multicellular behavior, within oomycetes-producing zoospores. Moreover, it will contribute to the development of biomimetic materials, as alternative to pesticides in oomycete outbreaks management.