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News
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The preprophase band of microtubules controls the robustness of division orientation in plants

L’orientation des divisions cellulaires joue un rôle important dans l’organisation spatiale des tissus de plantes. Une structure cellulaire particulière des cellules végétales, l'anneau de préprophase, est depuis sa découverte considérée comme l'acteur essentiel du positionnement du plan de division qui sépare les deux cellules filles. L'équipe IJPB de David Bouchez "Contrôle spatial de la division cellulaire" montre aujourd’hui que contre toute attente, cet anneau de préprophase intervient non pas dans le choix initial, mais plutôt dans la stabilisation du plan de division. Ces résultats sont publiés le 14 avril 2017 dans la revue Science.

L’organisation des divisions cellulaires dans le temps et dans l'espace est un élément majeur de la construction d’une plante. C’est, avec l’élongation cellulaire, le seul moteur de l’organisation tridimensionnelle des tissus végétaux car les cellules de plantes, liées les unes aux autres par une paroi rigide composée de cellulose, sont incapables de toute motilité au sein du tissu.

S'intéressant aux mécanismes moléculaires qui régissent l’organisation spatiale des divisions dans les cellules des plantes terrestres, des chercheurs de l’Inra se sont plus particulièrement focalisés sur la formation de l’anneau de préprophase (ou PPB). Structure cellulaire propre aux cellules végétales, il est considéré comme déterminant dans le choix du site de division au cours de la mitose, même si son rôle exact n’est pas totalement élucidé.

L’anneau de préprophase, un rôle stabilisateur…
Combinant des approches de génétique, de biochimie et de microscopie, les scientifiques ont d’abord obtenu, chez la plante modèle Arabidopsis thaliana, des mutants incapables de former l’anneau de préprophase avant la division cellulaire, sans autre conséquence sur le fonctionnement de la cellule. Très spécifiques, ces mutants leur ont permis d'étudier les effets de la perte de cette structure.
De façon inattendue, les chercheurs ont mis en évidence que, dans les cellules mutantes, la perte du PPB n’entraîne pas de bouleversements majeurs mais se traduit seulement par une orientation moins précise, plus variable des divisions cellulaires. Plus encore, chez ces mêmes mutants, la cellule reste capable de mettre en place un site de division à sa périphérie malgré l'absence de formation du PPB.

Autant de résultats qui suggèrent que le PBB a un rôle de stabilisateur et non de déterminant majeur dans l’orientation des divisions cellulaires chez les plantes terrestres.

... des rotations du fuseau mitotique

Le rôle de l’anneau de préprophase dans la stabilisation de l’orientation des divisions cellulaires serait lié à sa capacité à limiter les rotations du fuseau mitotique, un autre réseau de microtubules. Commun à tous les eucaryotes, le fuseau mitotique intervient dans la séparation des chromosomes pendant la division.

Renversant un dogme établi quasiment dès la découverte du PBB il y a cinquante ans, les chercheurs de l’équipe posent de nouvelles bases en ce qui concerne le contrôle spatial de la division des cellules végétales, et sa contribution au développement des plantes. Plus encore, leurs résultats donnent à penser que le facteur déterminant pour l’orientation des divisions cellulaires interviendrait en amont de l’établissement de l’anneau de préprophase, une hypothèse qu’ils vont maintenant s’employer à explorer à la faveur des outils génétiques qu’ils ont à disposition.

Estelle Schaefer, Katia Belcram, Magalie Uyttewaal, Yann Duroc, Magali Goussot, David Legland, Elise Laruelle, Marie-Ludivine de Tauzia-Moreau, Martine Pastuglia, David Bouchez, The preprophase band of microtubules controls the robustness of division orientation in plants. Science 14 Apr 2017: Vol. 356, Issue 6334, pp. 186-189 (PubMed Abstract)
DOI: 10.1126/science.aal3016

Scientific Contacts:
David Bouchez (01 30 83 36 93)
Martine Pastuglia (01 30 83 33 94)
Institut Jean-Pierre Bourgin (Inra, AgroParisTech, ELR CNRS)

Contact(s) presse :
Inra service de presse (01 42 75 91 86)
Département(s) associé(s) :
Biologie et amélioration des plantes
Centre(s) associé(s) :
Versailles-Grignon

Plus d'info : conmmuniqué de presse INRA

20th April 2017



Events
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Symposium IJPB 2018

March 19-20th 2018, INRA, Versailles, France

Registration deadline 28th february 2018

The First Symposium IJPB will offer a chance to listen to some of the best research developed at IJPB (but only a fraction of it!) with talks from David Bouchez, Nicolas Arnaud, Hervé Vaucheret, José Jiménez-Gómez, Raphaël Mercier, Enrico Magnani, Helen North, Stéphanie Baumberger, Bertrand Hirel. Contacts

As well as talks from prestigious external invited speakers:
Thomas Greb (Heidelberg University, Germany)
Claudia Köhler (Swedish University of Agricultural Sciences, Uppsala, Sweden)
Gwyneth Ingram (ENS Lyon, France)
Yves Van de Peer (Ghent University, Belgium)
Jonathan Jones (Sainsbury Laboratory, Norwich, United Kingdom)


Anne Krapp et Olivier Loudet

Programme and flyer

Scientific Committee : Nicolas Bouché, Jasmine Burguet, Sylvie Dinant, Jean-Denis Faure, Martine Gonneau, Herman Höfte, Anne Krapp, Patrick Laufs, Loïc Lepiniec, Olivier Loudet, Céline Masclaux-Daubresse, Raphaël Mercier, Christian Meyer, Helen North et Jean-Christophe Palauqui

Organizing Committee : Corine Enard (Institut Jean-Pierre Bourgin (IJPB), Versailles), Maria-Jesus Lacruz (IJPB, Versailles), Philippe Poré (INRA, Versailles) et Stéphane Raude (IJPB, Versailles)

Contact and more information: Symposium IJPB 2018 website



21th November 2017


 

Fascination of Plants Day 2017

La biologie végétale expliquée aux lycéens...

A l'occasion de cette journée, jeudi 18 mai 2017, l'Institut Jean-Pierre Bourgin accueille des lycéens pour leur faire découvrir la biologie des plantes. Elle est organisée par le Laboratoire d'Excellence Sciences des Plantes de Saclay (LabEx SPS).

Programme

Plus d'info
:
conmmuniqué de presse INRA

site Internet Fascination of Plant Day 2017



     

11th May 2017


 

"3èmes Journées du Réseau France Microtubules"
French Microtubule Network

3th & 4th Jully 2017, INRA, Versailles

 

Microtubules are found in almost all eukaryotic cells -from fungi and plants to mammals and human- and play a crucial role during mitosis as well as during interphase. Defects in microtubules organization or dynamics lead in animals to pathologies, such as metastatic tumors and neuronal diseases and in plants to altered development and reproduction.
The “Microtubule French Network“ has been created in 2013. This network has the ambition to gather every two years French groups and laboratories working in the microtubules field and using a wide variety of models, in various physiological, developmental, pathological or therapeutic situations. This symposium is held alternately with the international EMBO conference taking place in Heidelberg in even years. Previous editions of this symposium were held in Marseille in 2013 and in Grenoble in 2015, bringing together researchers, post-docs and students from over 34 laboratories. The 3rd days of the “French microtubules network” will be held in Versailles on July 3rd and 4th 2017.

Local Organization Committee: Katia Belcram (Institut Jean-Pierre Bourgin (IJPB), Versailles), Frédéric Coquelle (Institut Curie, Université Paris-Sud), Corine Enard (IJPB, Versailles), Benoit Gigant (I2BC, Gif-sur-Yvette), Maria-Jesus Lacruz (IJPB, Versailles), Christophe Leclainche (I2BC, Gif-sur-Yvette), Anne Nehlig (Institut Gustave Roussy, Villejuif), Martine Pastuglia (IJPB, Versailles), Philippe Porée (INRA, Versailles), Magalie Uyttewaal (IJPB, Versailles)

Scientifc committee: David Bouchez (IJPB, Versailles), Denis Chrétien (Institut de Génétique et Développement de Rennes, Rennes), Anne Fourest-Lieuvin (Grenoble Institut des Neurosciences, Grenoble), Stéphane Honoré (Centre de Recherche en Oncobiologie et Oncopharmacologie, Marseille), Andreas Merdes (Centre de Biologie Intégrative, Toulouse), Christian Poüs (Faculté de Pharmacie, Chatenay-Malabry)

Contact and more information: 3èmes Journées du Réseau France Microtubules website





11th May 2017


" Plant Epigenetics"

22th - 23th June, 2017 - Gif-sur-Yvette, France

The objective of this Symposium is to create a scientific event that is at the forefront of fundamental research on Plant Epigenetics.

The Symposium will bring together about 120 participants in a rather informal atmosphere, facilitating exchanges. We also aim at proposing a highly attractive program at a moderate inscription fee to give the opportunity to researchers - in particular those at the early stage of their career - to participate to an exciting top-level scientific event. Young researchers will have the opportunity to present their work.

Programme (fichier .pdf)

Scientifc committee:

Nicolas Bouché (IJPB), Martin Crespi, Moussa Benhamed, Abdel Bendahmane, Clémentine Vitte, Fredy Barneche, Vincent Colot, Jean Molinier

For more information, Please contact and visit the websitePlant Epigenetics Meeting



11th May 2017


" Bilateral Closure Symposium of GDRI Integrative Plant Biology Network"

23th-25th october, 2017 - Lyon, France

This network gathering French and Japanese laboratories, working in the field of plant biology,organized and supported bitateral actions from 2014 to 2017.

.

Programme (fichier .pdf)

Le comité scientifique :
Thierry GAUDE (ENS de Lyon), Gwyneth INGRAM (ENS de Lyon, France), Loïc LEPINIEC (IJPB, INRA, Versailles), Annie MARION-POLL (IJPB, INRA, Versailles), Laurent NUSSAUME (BIAM, CEA, Cadarache), Akira SUZUKI (IJPB, INRA, Versailles), Mitsunori SEO (RIKEN, Yokohama, Japan), Hidehiro FUKAKI (Kobe University, Kobe, Japan), Kohki YOSHIMOTO (Meiji University, Kawasaki, Japan), Kimitsune ISHIZAKI (Kobe University, Kobe, Japan)

Pour plus d'information, merci de visiter le site GDRI-IPB

29th June 2017


Séminars
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____________________________________________________

Monday 16th january 2017

_______________________________________________
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2:00 PM
Invited Speaker

Dr. Grégory VERT
(Institute for Integrative Biology of the Cell (I2BC), Department of Cell Biology, CNRS, Gif/Yvette)
Zooming in and out on ubiquitin-dependent regulatory mechanisms

As sessile organisms, plants are fixed to a specific location. They have therefore evolved sophisticated strategies to constantly monitor and respond to ever changing environmental conditions by adjusting their growth and development. My lab has long been studying the regulatory mechanisms allowing plants to fine tune and integrate signaling pathways to create robust responses to both endogenous and exogenous cues. Ubiquitin-dependent processes play a paramount role in the control of basic cellular processes and in the regulation of signaling pathways. Except for lysine-48-linked polyubiquitin chains, which mediate proteasome-dependent degradation, our knowledge about all other types of post-translational modifications involving ubiquitin is still scarce. Over the past few years, my lab has been deconstructing the networks and role(s) of the second most abundant and yet poorly-characterized ubiquitin form using plants as model. We have initiated the identification of the machinery driving the formation of lysine-63 polyubiquitin chains, and have characterized the prominent role of K63 polyubiquitination in the dynamics of plant cell-surface proteins and its contribution to growth and development in the context of a fluctuating environment.

Grégory VERT : Signalisation Cellulaire et Ubiquitination chez les Plantes : http://www.i2bc.paris-saclay.fr/spip.php?article129&lang=fr

Invité par Alia Dellagi

_________________________________________________

Friday 20th January 2017

_______________________________________________
____

9:30 AM
Bibliothèque physio-phyto Bât. 2

Visitor

Dr. Stéphane NICOLAS
(Génétique Quantitative et Évolution
Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Gif/Yvette)
Deciphering the genetics of complex traits and diversity using high-troughput genotyping approaches in maize: New prospects for old challenges

Invited by Sylvie Coursol

___________________________________________________

Monday 30th January 2017

_______________________________________________
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2:00 PM
Invited Speaker

Dr. Marie-Laure MARTIN-MAGNIETTE
(Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universités Paris-Sud, Evry, Paris-Diderot, Sorbonne Paris-Cite, Paris-Saclay, Orsay,
Mathématiques et Informatique Appliquée (MIA-Paris), AgroParisTech, INRA, Université Paris-Saclay)

From gene expression modeling to gene network to investigate Arabidopsis thaliana stress response

Transcriptome data allow investigating the gene behaviors and co-expression studies have rapidly been considered as a way to identify sets of candidate gene modules. Generally co-expression is established by analyzing correlations between all gene pairs in multiple microarray experiments collected from public repositories. Such approaches may suffer from both heterogeneity of data and the choice of the clustering method, usually based on gene pairs.
Tackling these limitations, we propose an analysis based on a large and homogeneous set of transcriptome data extracted from CATdb: 387 stress conditions organized into 9 biotic and 9 abiotic stress categories. Instead of correlation analysis, a model-based clustering was applied to identify clusters of co-expressed genes per stress category. Various resources were then analyzed and integrated to characterize functions associated with genes in these clusters. Protein–protein interactions and transcription factors-targets interactions were exploited to display gene networks. All the results are stored and managed in GEM2Net, a new module of CATdb (Zaag et al., 2015). We are currently using this resource to identify a coregulation network and possible determinants of expression regulation. We are also proposing a high-throughput functional annotation of Arabidopsis thaliana. During my talk, I will present these different projects.

ML Martin-Magniette Team : http://www.ips2.u-psud.fr/spip.php?rubrique69&lang=en

Invited by Catherine Rameau

____________________________________________________

Thusday 23th March 2017

_______________________________________________
_____

2:00 PM
Grande salle de réunion Bât.7
Visitor

Dr. Mireille BETERMIER
(Réarrangements programmés du génome, Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Gif/Yvette)

Developmentally programmed dynamics of the somatic genome in the ciliate Paramecium

Invited By Mathilde Grelon

____________________________________________________

Friday 12th May 2017
_______________________________________________
_____

11:00 AM
Visitor
Pr. Dominique LOQUÉ
(Microbiology, Adaptation and Pathogenesis, Université Lyon 1, Univ. of California, USA)
Development of Novel Approaches to Optimize Energy Crop

Development of highly performant energy-crops is needed to provide sustainable and large resources of biomass to feed our biorefineries and to support cost-effective conversion of the biomass into biofuels and bio-products. Plant biomass is mainly composed of polymers made of fermentable sugars (cellulose and hemicellulose) that are embedded in a robust aromatic polymer called lignin. Recalcitrant to degradation, lignin inhibits efficient extraction and hydrolysis of cell wall polysaccharides and prevents low-cost lignocellulosic-biofuel production. Unfortunately, content and composition of these polymers cannot be drastically manipulated to the same extend in all tissues without causing deleterious consequences on plant productivity. Therefore, technologies allowing precise manipulation of content and composition of various components of plant cell walls should be developed to facilitate the production of cheap and large quantities of fermentable sugars without compromising plant growth. Moreover, engineering plants with complex metabolic pathways or multiple traits is often inhibited by the number of genes that are required to reach the final product. This presentation will highlight our progress in crop engineering. In addition to biomass trait engineering strategies, it will include tools such as in vitro and in vivo DNA assembly methods to stack multiple gene cassettes, promoter libraries developed to support tissue specific expression, and approaches used to support expression strength and precision of one and multiple genes in plants. We are convinced that the development of these tools and approaches will offer new directions to support basic science and the optimization of agronomical and energy traits. They will also provide support to scientists and engineers who are looking at stacking and controlling multiple genes and interested in manipulating endogenous metabolic pathways.

Invited by Herman Höfte

____________________________________________________

Monday 22th May 2017
_______________________________________________
_____

2:00 PM
Visitor
Dr. Christian VOIGT
(Department of Animal and Plant Sciences, University of Sheffield, GB)
Improving plant resistance to fungal pathogens by callose modification


Invited By Samantha Vernhettes

___________________________________________________

Tuesday 23th May 2017
_______________________________________________
_____

11:00 AM
Invited Speaker
Dr. Johnathan NAPIER
(Rothamsted Research, Harpenden, GB)
Metabolic engineering of the omega-3 long chain polyunsaturated fatty acid pathway
in transgenic Camelina saliva -making fish oils in plants

We have been evaluating the possibility of producing omega-3 LC-PUFAs in different transgenic hosts, to provide a sustainable source of these important nutrients. Attempts to metabolically engineer plants with the primary algal biosynthetic pathway for LC-PUFAs has been successfully carried out in a range of species, allowing insights into factors constraining the accumulation of these fatty acids in non-native hosts. The use of lipidomics has allowed us to identify further metabolic bottlenecks in the transgenic pathway, ultimately leading to the breakthrough production of a transgenic oilseed crop which contains up to 30% omega-3 LC-PUFAs in its seed oil. This omega-3 trait represents probably the most complex plant metabolic engineering to undergo field-trialing to date, and as such, has implications for applied synthetic biology in agriculture. Recently, we have evaluated the use of glasshouse-grown GM Camelina seed oil as a replacement for fish oil in aquafeed diets, observing effective substitution in feeds for salmon and sea bream. These data further confirm the potential of these novel oils and their potential role in human nutrition, direct or otherwise


Johnathan Napier web page : http://www.rothamsted.ac.uk/people/napier



Invited by Herman Höfte
____________________________________________________

Monday 12th June 2017
_______________________________________________
_____

2:00 PM
Visitor
Dr. Emmanuelle SCHMITT
(Laboratoire de biochimie, Démarrage de la traduction,
CNRS, Ecole polytechnique, Palaiseau)
Structural and functional studies of the translation initiation factor e/alF2


Eukaryotic and archaeal translation initiation complexes have in common a functional core containing mRNA, the ternary initiation complex (e/aIF2, GTP, Met-tRNAiMet), e/aIF1 and e/aIF1A bound to the small ribosomal subunit. In eukaryotes, the functional core is made more complicated by many additional factors, most of them being involved in a long-range scanning of mRNA, necessary to decipher the initiation codon. In archaea, long-range scanning does not occur thanks to the occurrence of Shine-Dalgarno sequences or of very short 5’ untranslated regions on mRNA. Concomitantly, archaeal translation initiation only requires the core complex. Within the core complex, e/aIF2, in its GTP-bound form, is responsible for selecting the methionylated initiator tRNA and bringing it to the small ribosomal subunit. The establishment of the connection between the start codon on the mRNA and the anticodon of the initiator tRNA is also coupled to the release of one molecule of phosphate resulting from the hydrolysis of GTP bound to eIF2. The function of the e/aIF2 protein in eukaryotes and archaea is therefore crucial for translation initiation. We have been studying factor e/aIF2 for the last few years. In particular, using eukaryotic or archaeal versions of this factor, many data have been accumulated to help understand how it operates. Finally, using purified versions of the archaeal translation initiation complexes, we recently solved the structure of two stages of archaeal translation initiation by Cryo-EM. The two snapshots highlight a new network of interactions crucial for translation initiation in archaea. According to the conservation of the core complex in eukaryotes, this network of interactions is also anticipated to be relevant for the eukaryotic translation initiation process.


Invited by Thierry Chardot
____________________________________________________

Later on
Friday 23th June 2017

_______________________________________________
_____

2:00 PM
Grande salle Bat 7

visitor
Pr. Meike BUROW
(Plant and Environmental Sciences, University of Copenhagen, Danmark)

Feedback regulation of metabolism and development by glucosinolate defense compounds


Glucosinolates are well known as direct mediators of biotic and abiotic stress responses and more recent work revealed that they feedback-regulate their own biosynthetic pathway in a structure-specific manner.
To identify the mechanisms that allow the plant to specifically sense glucosinolate structures, we conducted a survey of transcriptomic responses to the application of exogenous glucosinolates.
AOP2 and AOP3 feedback regulate their own pathway and link to jasmonate signaling, primary nitrogen metabolism, the circadian clock, and the onset of flowering. Thus, glucosinolates have the capacity to provide regulatory input to their own and other regulatory networks. As the effect on flowering time is dependent on the genetic background, natural variation in this cross-talk between defense chemistry and development might reflect an adaptation to survival in different environments.


Invited byChristian Meyer
____________________________________________________

Monday 26th June 2017
_______________________________________________
_____

2:00 PM
Visitor
Dr. Akira IWASE
(Epigénomique et épigénétique chez la plante Arabidopsis, IBENS, ENS Paris
RIKEN CSRS, Japon)

Stress-induced plant cell reprogramming: Accelerators and brakes for regeneration


Many plant species display remarkable regeneration ability upon severe environmental stresses, especially wounding 1. Plants often repair the wounded sites via the formation of unorganized cell mass called callus and regenerate new organs from callus cells. This potential is exerted only when plants encounter stresses, therefore plant cells must possess two mechanisms; one is to promote callus induction and tissue regeneration at wound site, another is to prevent unscheduled regeneration in normal development. However, molecular mechanisms on the two mechanisms are still elusive. We previously identified an AP2/ERF transcription factor WOUND INDUCED DEDIFFERENTIATION 1 (WIND1), and its close homologues WIND2, WIND3 and WIND4 are the central regulators of wound-induced cellular reprogramming in plants2. All of the WIND genes are strongly activated by wounding, and overexpression of each of WIND genes is sufficient to produce callus in wild-type plants. Interestingly, we often observe regeneration phenomena from WIND1-indiced callus, and have recently discovered another AP2/ERF transcription factor ENHANCER OF SHOOT REGENERATION1 is one of direct targets of WIND1 to promote callus formation as well as shoot regeneration at wound site3. We have also recently uncovered that some of the WIND genes need to be epigenetically silenced to maintain the differentiated status of mature plant cells4. In this talk, I will discuss how wound stress promotes cellular reprogramming leading to regeneration, and how mature plant cells repress unscheduled dedifferentiation.


Invited by Marco Da Costa & Philippe Rech
____________________________________________________

Wenesday 28th June 2017
_______________________________________________
_____

2:00 PM
Grande salle Bât. 7
Visitor
Pr. Bernard CARROLL
(School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australie)

Systemic RNA silencing in plants


Post-transcriptional gene silencing (PTGS) is graft-transmissible and involves abundant 21 nt siRNAs and low abundance 22 nt siRNAs produced by DCL4 and DCL2, respectively. We developed a reporter line expressing double-stranded RNA (dsRNAs) specifically in the root tip, which then required RNA-dependent RNA polymerase 6 (RDR6) for PTGS to spread from the root tip to throughout the plant. This reporter line was used in a genetic screen to identify mutants impaired in systemic PTGS. As expected, the screen identified new alleles of rdr6 and other genes known to be required for RDR6-dependent PTGS. Surprisingly, however, we also recovered dcl2 but not dcl4 mutants. Thus, even though DCL4 outcompetes DCL2 for siRNA biogenesis in wild-type plants, DCL2 is crucial for systemic RDR6-dependent PTGS. Other genes required for systemic PTGS will also be discussed. Finally, the potential of topical application of double-stranded RNA for inducing systemic RNA silencing in plants will also be discussed.


Invited by Hervé Vaucheret
___________________________________________________

Friday 1st September 2017
_______________________________________________
_____

9:30 AM
Bibliothèque physio-phyto Bât.2
Visitor
Pr. Shaul YALOVSKI
(Tel Aviv University, Israël)
Intersection of ROP and Ca2+ signaling during root growth and development

Invited by Herman Höfte
____________________________________________________

Monday 11th september 2017
_______________________________________________
_____

2:00 PM
Focus Seminar IJPB
Dr. Christian MEYER
(Team "Signalisation, Transport et Utilisation de l’Azote")
The plant Target of Rapamycin kinase: a central translaTOR of environmental information

___________________________________________________

Friday 29th september 2017
_______________________________________________
_____

9:30 AM
Bibliothèque physio-phyto Bât. 2
Visitor
Dr. Nadine PARIS
(Equipe "KaliPHruit", Biochimie et physiologie moléculaire des plantes, SupAgro, Montpellier)

New fluorescent ratiometric pH sensors to study proton homeostasis in living plants

Invitée par Herman Höfte
___________________________________________________

Tuesday 3th october 2017
_______________________________________________
_____

11:00 AM
Visitors
Dr. Jean-Luc GALLOIS et Anna BASTET
(Résistance aux Virus, Génétique et d’Amélioration des Fruits et Légumes (GAFL), INRA, Avignon)

Résistances aux virus médiées par eIF4E : de la variabilité naturelle aux allèles synthétiques

eIF4E translation initiation factors have emerged as major susceptibility factors for RNA viruses. Natural eIF4E-based resistance alleles are found in many species and are mostly variants that maintain the translation function of the protein. eIF4E genes represent major targets for engineering viral resistance, and gene-editing technologies can be used to make up for the lack of natural resistance alleles in some crops, often by knocking out eIF4E susceptibility factors. However, we report here how redundancy among eIF4E genes can restrict the efficient use of knockout alleles in breeding. We therefore discuss how gene-editing technologies can be used to design de novo functional alleles, using knowledge about the natural evolution of eIF4E genes in different species, to drive resistance to viruses without affecting plant physiology.

Invited by Fabien Nogué
___________________________________________________

Monday 9th october 2017
_______________________________________________
_____

14:00 PM
Visitor
Pr. Luis VIDALI
(Biology & Biotechnology Dtp, Worcester Polytechnic Institut, Massachusetts, US)
The moss Physcomitrella patens as a model system to investigate polarized cell growth

Contact : Fabien Nogué
___________________________________________________

Thursday 19th october 2017
_______________________________________________
_____

2:00 PM
Visitor
Dr. Sebastian MARQUARDT
(Non-Coding Transcription, Copenhagen Plant Science Centre, University of Copenhagen, Danemark)

Rules and Roles of non-coding Transcription

RNA Polymerase II (Pol II) transcription occurs mainly outside of genes, which is referred to as “pervasive transcription”. This raises the question: does pervasive transcription serve a purpose? My lab studies the roles of pervasive transcription near genes in yeast and plants. Long non-coding RNA (lncRNA) molecules can serve important functions in cells, for example by recruiting chromatin modifying enzymes to target loci. However, lncRNA often lack sequence conservation and accumulate to low levels as they are targeted for degradation by nuclear RNA decay pathways. These considerations pose a challenging question to the field: how could lncRNA that are not conserved on sequence level nevertheless elicit equivalent functions? My lab addresses this question by focusing on gene regulation through the process of transcribing lncRNA in the vicinity of genes. Proper execution of gene expression by Pol II relies on a “positional information” system across genes. As lncRNA and mRNA Pol II transcripts use similar molecular hallmarks to inform the positional information system, lncRNA transcription near genes can confuse this system to affect gene expression. I will present our latest findings addressing gene regulation through the act of non-coding Pol II transcription in yeast and plants.


Invité par Grégory Mouille
___________________________________________________

Tuesday 31th October 2017
_______________________________________________
_____

11:00 PM
Bibliothèque physio-phyto Bât. 2
Visitor
Dr. Pradeep DAS
(Biophysique et développement,
Reproduction et Developpement des Plantes, ENS, Lyon)

Patterning and morphogenesis during early flower development

The mechanisms that drive growth, development and morphogenesis in plants and animals have been an important area of investigation for decades. It is clear that the emergence of stereotypical positions, shapes and sizes of tissues or organs requires the coordinated regulation of very specific growth patterns across space and time during development. Much of this coordination occurs via signalling cues provided by growth regulators (morphogens, growth factors etc.). In this context, our group seeks to gain a clearer understanding of how flower development in the model plant Arabisopsis thaliana, is governed by the underlying molecular, genetic and physical events. While much is known about the genetics of flower development, much less is known about its mechanical aspects, and about how growth manifests at a physical level. The most obvious way to measure and describe growth is at the cellular level, and to this end, we have developed an experimental method to computationally track the growth of Arabidopsis flowers at cell resolution and in four dimensions. We use this resource to address different aspects of patterning and morphogenesis in the flower. I will present two such projects below. The first aims to explore the molecular mechanisms necessary for the establishment of very specific spatio-temporal floral gene expression patterns. The second project revolves around the increased mechanical rigidity that we have recently observed in stem cells at the shoot apex; I will outline our efforts to understand the role of this increased stiffness on plant morphogenesis.


Invité par : Léo Serra et Patrick Laufs
____________________________________________________

Monday 6th November 2017
_______________________________________________
_____

2:00 PM
Bibliothèque physio-phyto Bât. 2
Visitor
Dr. Jason W. REED
(The University of North Carolina at Chapel Hill, USA)

Auxin regulation of elongation in seedlings and flowers

Invited by:
___________________________________________________

Thursday 9th november 2017
_______________________________________________
_____

2:00 PM
Invited Speaker
Pr. Alexis MAIZEL
(Centre for Organismal Studies, University of Heidelberg, Allemagne)


Lateral root morphogenesis in Arabidopsis thaliana

Plants form new organs with patterned tissue organization throughout their lifespan. As plants cells are encaged in a rigid cell wall cell migration is impossible. In consequence, plants rely on oriented cell divisions and anisotropic growth to shape their organs and precisely organise their tissues.
Lateral roots are formed postembryonically and determine the final shape of the root system, a determinant of the plants ability to uptake nutrients and water. Lateral root formation commences when founders cells located in the pericycle divide and create a dome-shaped lateral root primordium (LRP), which has to cross three overlying tissues to emerge at the surface of the parent root: the adjacent endodermis, the cortex and the outermost layer, the epidermis. In a previous work [1], we combined modelling with empirical observations using light sheet microscopy of whole organ development to identify the principles governing lateral root formation in Arabidopsis. Lateral roots derive from a small pool of founder cells, in which some take a dominant role as seen by lineage tracing. The first division of the founders is asymmetric, tightly regulated, and determines the formation of a layered structure. Our recent results indicate that auxin plays a crucial role in the control of this first essential formative division. To preserve the structural and functional integrity of the primary root, it is necessary to coordinate growth and proliferation within the LRP and the responses of the overlying tissues. Auxin plays a pivotal role in coordinating these responses. Our results show in particular that auxin controls the dynamics of cortical microtubule rearrangements which has a critical impact on the control of plane of division and the ability of cells to alter their geometry.

[1] Wangenheim, von, D.et al (2016). Curr Biol 26, 439–449

Maizel Lab: http://www.maizel-lab.org/

Invited by:

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Monday 13th November 2017
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2:00 PM
Invited Speaker IJPB/SPS
Dr. Kentaro TAMURA
(University of Kyoto, Japan)

The functional versatility at the nuclear pore complex in higher plants:

The nuclear pore complex (NPC) is composed of more than 30 nucleoporins (Nups) and regulates macromolecular trafficking between the nucleoplasm and the cytoplasm in eukaryotes. In 2010, we successfully revealed the overall molecular structure of plant NPC by using an interactive proteomic approach, which identified novel 22 nucleoporins. Recently, we found that two plant specific nucleoporins function in plant immunity response. In this seminar, I will introduce our recent works and discuss the versatile function of plant NPC.

Invited by: Valérie Gaudin
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Monday 27th November 2017
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2:00 PM
Focus Seminar IJPB
Dr. Sébastien BAUD
(Team "Development and seed quality"
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Plant-based omega-7 fatty acids, molecules of therapeutic and industrial interest

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Monday 29th January 2018
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2:00 pm

Invited Speaker
Pr. Oren OSTERSETZER-BIRAN
(Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel)

Plant mitochondria group II introns splicing: A window into the evolution of the nuclear spliceosomal machineries

Mitochondria serve as principal sites for cellular energy metabolism and play pivotal roles in the biosynthesis of many essential metabolites for the (plant) cell. As dependences of a free-living organism, mitochondria contain their own genome, the mtDNA. The mtDNAs in plants are notably larger and more complex in structure than their corresponding ones in Animalia. Plant mitochondria are also remarkable with respect to the presence of numerous group II introns that reside in many organellar genes. The removal of the introns from the coding sequences they interrupt is essential for respiratory functions and is mediated by enzymes that belong to a diverse set of protein-families. These include intron-encoded related proteins (i.e. maturases) that function in the splicing of group II introns in bacteria and mitochondria in fungi and plants, usually with high specificity towards the intron in which they are encoded. While the splicing of group II introns in vivo is facilitated by maturase factors, canonical group II introns are catalytic RNAs that are able to excise themselves from their pre-RNA hosts in vitro, in the absence of the protein cofactors, using a mechanism identical to that utilized by the spliceosome. Structural analyses and phylogenetic data may indicate that the spliceosomal RNAs have evolved from group II intron-related ancestors. Yet, it remains unclear how could such general players in spliceosomal splicing evolve from the monospecific bacterial systems (i.e. a group II intron RNAs and their highly specific intron-encoded maturase factors). Analysis of the organellar splicing machinery in plants may provide us with important clues into the evolution of the nuclear splicing machineries. Genetic and biochemical studies led to the identification of different protein factors that facilitate the splicing of many of the mitochondrial introns in plants. We established the native RNA targets of different maturase factors in plants and analyzed the organellar and developmental defects associated with their mutant lines in vivo. Interestingly, while model maturases in bacteria and fungi mitochondria act specifically on their cognate intron RNAs, the plant maturases are acting on multiple mtRNA targets, thus seem to be acting as organellar proto-spliceosomal factors. The ability of the mitochondrial maturases in plants to act on different intron targets further support the notion that the early organellar self-splicing and mobile group II RNAs spread in the eukaryotic genomes and later ‘degenerated’ into the universal splicing system, known as the spliceosome. The similarities between maturases and the core spliceosomal factor, Prp8, may support this intriguing hypothesis.

Oren Ostersetzer-Biran webpage

Invited by:  

Registration compulsory up to 25/01/18
Except for INRA Versailles members

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Seminars location except other indications
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Amphitheatre, Building 10
INRA Centre de Versailles-Grignon
Route de St Cyr (RD10)
F-78026 Versailles Cedex
France

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