Développement racinaire du peuplier en réponse aux signaux fongiques lors de la mise en place de l'ectomycorhize, Poplar root development in response to fungal signals during onset of ectomycorrhiza development

Judith Richter

Description

Sous la direction de Francis Martin, Klauss Palme
Thèse soutenue le 14 décembre 2009: Université de Fribourg (Allemagne), Nancy 1
Développement racinaire du peuplier en réponse aux signaux fongiques lors de la mise en place de l'ectomycorhize Résumé français : L'interaction précoce entre les racines des arbres et les champignons ectomycorhiziens (CEM) est accompagnée d'une forte stimulation du développement de racines latérales (RLs) de la plante hôte. L'objectif de cette thèse est de décrypter les mécanismes moléculaires impliqués dans le développement des RLs de Populus tremula x Populus alba (espèce mycorhizienne) et d'Arabidopsis thaliana (espèce non-mycorhizienne) en réponse au champignon ectomycorhizien Laccaria bicolor. L'auxine étant considérée comme un élément clef de la régulation du développement des RLs, nous avons focalisé notre étude sur les protéines impliquées dans le transport et la signalisation de cette hormone. Nos résultats moléculaires (NimbleGen microarray, RT-PCR quantitative) illustrent que la présence du champignon altère le gradient auxinique dans les racines via une modification de l'expression de PtaPIN9 (AtPIN2), impliqué dans le transport polarisé de l'auxine. Des analyses de plantes mutantes ont suggéré que la stimulation des RLs lors du contact plante/champignon dépend de ce transporteur ainsi que de la signalisation auxinique dans les racines. Notre étude a été élargie à la recherche de molécules émises par le champignon qui interféraient avec les voies auxiniques de la plante. Nos résultats révèlent l'implication des voies de l'éthylène, des jasmonates, des brassinostéroides et des ROS (Reactive Oxygen Species) pendant l'interaction plante/champignon, suggérant une implication des voies de signalisation dépendantes des stress dans les étapes précoces de l'interaction. Nous proposons que Laccaria bicolor stimulerait le développement des RLs en modifiant la répartition et la signalisation de l'auxine endogène de la racine via les voies de signalisation du stress.
-Ectomycorhizes
-Auxine
-Racine latérale
-Transcriptomique
-Phytohormone
-Peuplier
The early phase of the interaction between tree roots and ectomycorrhizal (ECM) fungi is accompanied by a stimulation of lateral root (LR) development. This thesis aims on understanding by which molecular mechanisms the interaction of plant and fungus induces LR stimulation. Therefore the ECM fungus L. bicolor in interaction with one of its mycorrhizal hosts, Populus tremula x Populus alba or with the non-mycorrhizal herbaceous model plant Arabidopsis thaliana was studied. We identified gene networks that regulate LR development during the early signal exchanges between Populus tremula x Populus alba and the ECM fungus Laccaria bicolor. We focussed on auxin transport and signalling pathways, as those are key actors regulating LR development. Experiments with poplar and Arabidopsis transgenic auxin response marker lines revealed that the presence of fungal signalling molecules modified auxin gradients in roots. Using microarray- and quantitative Real-time PCR based transcript profiling of poplar roots we uncovered the accumulation of transcripts of the polar auxin efflux carrier PtaPIN9 as well as of auxin responsive transcription factors. A. thaliana transgenics defective in these targets showed that they are crucial for fungus induced LR stimulation. Finally we identified an involvement of ethylene, jasmonates, brassinosteroids and ROS (Reactive Oxygen Species) signalling during fungal LR induction. These pathways are known to be activated upon stress responses in the plant and to interact with auxin pathways. Together these data show how ECM fungi stimulate LR development in plants by interfering with endogenous auxin-levels, -distribution and -signalling most probably through stress signalling pathways.
Source: http://www.theses.fr/2009NAN10110/document

Sujets

• Auxine
• Transcriptomique
• Phytohormone
• Peuplier

Informations

• Publié par: Thesee
• Nombre de lectures: 69
• Langue: Français
• Poids de l'ouvrage: 7 Mo

Extrait

AVERTISSEMENT

Ce document est le fruit d'un long travail approuvé par le
jury de soutenance et mis à disposition de l'ensemble de la
communauté universitaire élargie.

Il est soumis à la propriété intellectuelle de l'auteur. Ceci
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D’autre part, toute contrefaçon, plagiat, reproduction
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➢ Contact SCD Nancy 1 : [e-mail]




LIENS


Code de la Propriété Intellectuelle. articles L 122. 4
Code de la Propriété Intellectuelle. articles L 335.2- L 335.10
http://www.cfcopies.com/V2/leg/leg_droi.php
http://www.culture.gouv.fr/culture/infos-pratiques/droits/protection.htm
Université Henri Poincaré I, Faculté de Sciences Albert-Ludwigs Universität Freiburg
U.F.R. Sciences et Techniques Biologiques Fakultät für Biologie
Ecole Doctorale « Ressources Procédés Graduiertenkolleg GRK1305 « Signal
Produits Environnement » systems in plant model organisms »

UMR 1136 INRA/UHP AG Palme
Interaction Arbres/Microorganismes Institut für Biologie II
Centre INRA de Nancy


Thèse en co-tutelle franco-allemande

Présentée pour lʼobtention du titre de docteur de
lʼUniversité Henri Poincaré, Nancy 1 Biologie Végétale et Forestière
et de la Fakultät für Biologie, Albert-Ludwigs Universität Freiburg

Par
Judith RICHTER FELTEN


Titre
Développement racinaire du peuplier en réponse aux signaux
fongiques lors de la mise en place de lʼectomycorhize

Poplar root development in response to fungal signals during onset of
ectomycorrhiza development

Thèse soutenue le 14 Décembre 2009

Membres du Jury

Rapporteurs
Laurent Laplaze Chargé de Recherche, Centre IRD de Montpellier
Uwe Nehls Professeur, Universität Bremen (Allemagne)

Examinateurs
Franck Ditengou Assistant Professeur, Universität Freiburg (Co-directeur de thèse)
Valérie Legué Maître de Conférence, INRA Nancy/UHP (Co-directrice de thèse)
Francis Martin Directeur de Recherche, INRA Nancy (Directeur de thèse)
Klaus Palme Professeur, Universität Freiburg (Directeur de thèse)

Président de Jury Uwe Nehls
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Our head is round, so our thinking can change directions.
Francis Picabia


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Acknowledgements
I am grateful for the financial support of this work by the European Commission within the Seventh
Framework Program for Research, Project Energypoplar (FP7-211917), the EVOLTREE network of
excellence, the French Space Agency (CNES), the French Ministry for Higher Education and
Research, the International Graduateschool GRK1305 (Freiburg University) and mobility grants
from the German-French University (DFH and Egide/Procope (DAAD) (German-French Research
Cooperation) from the.
I thank Laurent Laplaze, Uwe Nehls and Michel Chalot as members of my jury for giving me the
honour of accomplishing my PhD under their experienced and critic view. MERCI in advance for your
opinion on my work that will encourage me to become still more sharp-sighted but also, I hope,
more open-minded in my future research.
During the last three years many people had their hands in giving me an excellent time, with their
scientific or other support, their ideas, their good humour and the time they spent listening whenever
there was a problem. Saying MERCI to everyone is maybe the most challenging part of a PhD project,
if it comes to the point of not forgetting anyone. So first, I want to apologize and to say MERCI to
everyone who cannot find his or her name within these two pages but who has helped me in one way
or another.
MERCI to Francis and Klaus, my official supervisors, for having received me as a member of your
labs and for your support of my work. I am grateful for each moment of your tight work-schedule
you took to listen to my ideas, to support me or to bring me back onto the right way and to give me
new impulses of inspiration. There were some moments when I though I hit rock bottom and talking
to you always gave me new energy to get over them. MERCI also for your faith in me and my work
and for the numerous possibilities you have given me to get in touch with excellent researchers
outside of your labs and to present my work.
Valérie and Franck, the next MERCI is for you. You had the idea to set up as co-supervisors this co-
tutelle PhD project and I’m happy that you have made me your choice as a candidate. I’m glad to
have had the opportunity to work in such an exciting field with so many tools (as made by the
combination of both labs) and especially with you. You have founded and enriched this work but
you also knew how to leave me enough liberty to make up and work out my own ideas, while always
keeping an experienced eye on what I did. I thank you both for the time I spent with each of you in
front of the microscope to try to convince the world with our results that microscopy is not only
“BEAU” but that there’s something more about it than just making decorative images.
Valérie, your enthusiasm and inexhaustible energy were a big motivation for me everyday we
worked together. Due to your brilliant teaching, I learned tons of things about confocal microscopy –
but I hope you will reveal some more secrets to me before I leave! You always tried to find time,
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even if there was none, to help me when my days would have needed 36 hours to finish the work I
planned (I should have learned more in my Time-Management lecture concerning this!). You
reassured me, whenever I was too impatient, and always found a solution to get things going.
Sharing your excitement about our results was a big pleasure. I had a great time with you in and
outside the lab and will miss this.
Franck, I’m glad you always had a more critical opinion than everyone else and opened my mind to
new ideas. I learned from you how and what to observe in a root and how to exercise care when
interpreting results. I would have liked spending more time in Freiburg to learn still more and to try
out new things. Unfortunately I didn’t manage to clone myself within these three years but I keep on
trying!
From the UMR 1136 in Nancy I say MERCI to: Annegret for your advice during microarray analysis,
Joëlle and Jean-Pierre L. for your excellent technical support at UHP, Zachary and Céline for having
worked with me during your lab-projects and having asked me many questions that made me think a
lot, Emilie, Manu and Benoit for the bioinformatics support, Mélanie from Jean-Pierre’s lab for
instructions for Western-Blotting and Nico for exchanging about ROS in ECM, Michel for having
given me the possibility to make auxin-quantification experiments in your lab and for discussions
with you, Frédéric and Eva from Michel’s lab for your help with the GC-MS, Nicole and Marie-
Claude from INRA and Chantal from UHP for your administrative work. MERCI to the people who
have made the daily lab-life so pleasant: Vero for being gifted with your calm temper and for always
having an open ear to me, Jessy for your good mood and your ideas that solve any problem, Jonathan
for having shared the last year of my work with a lot of fruitful and lively discussions and Krista for
proofreading my texts, Stéphane for having worked out during your Master’s project a basis for my
PhD project and for your ideas to make the doc’s and postdoc’s lab-life a bit more animated, Jaime
for having helped me practicing my Spanish and for having made me discover the Chilean cuisine,
Bea for your company clearing out the dishwasher (raller ensemble c’est mieux que de raller toute
seule), Christine for placing urgent orders for me, and Patrice for taking care of the greenhouse and
growth-chamber. MERCI to Jean-Louis’ calm hand whenever the balance-bubble of the balance didn’t
want to go into the centre of the circle (je n’aime vraiment pas ce jeu), to Stéphane U., Marc, Seb,
Annick and Claire for your advice and discussions, to Sara, Angela, Adeline, Christelle, Carine,
Felicia, Cyrille, and Claude for the good atmosphere in the lab and to François le Tacon and Jean-
Garbaye for being the “wise-men” of the lab.
From Klaus Palme’s lab: Katja, MERCI for the excellent technical support, the nice discussions and
all the seeds you got urgently to me, Philipp, MERCI for your precious advice on protocols, Tarasz,
MERCI for your instructions for ROS measurements, Cri and Sasha, MERCI for having offered me
several times a bed in your house when I came to Freiburg and Cri for the excellent Italian cuisine
and for organizing the pub evenings, Dorothée, MERCI for the nice dinners, Karsten, MERCI for
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having laughed about the French accent you always told me I had in German when just coming from <