Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free: https://www.ghostery.com/fr/products/

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site: http://www.youronlinechoices.com/fr/controler-ses-cookies/, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Realytics
Google Analytics
Spoteffects
Optimizely

Targeted advertising cookies

DoubleClick
Mediarithmics

The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at cil-dpo@inra.fr or by post at:

INRA
24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal Labex TULIP CNRS

Laboratory of Plant-Microbe Interactions - LIPM

Laboratory of Plant-Microbe Interactions

Research themes - Symbiotic functions, genome and evolution of rhizobia

cAMP signalling and autoregulation in the Sinorhizobium meliloti – Medicago symbiosis.

In contrast to the situation in animal pathogens, cAMP signaling in symbionts such as the legume symbiont S. meliloti has received little attention so far. Yet the large number of adenylate cyclases in rhizobia (27 in S. meliloti) suggest they play a prominent role in the rhizospheric and/or symbiotic life of rhizobia.

We focus our research on three adenylate cyclases and their cognate transcriptional regulator called Clr that regulate secondary infection of Medicago roots by S. meliloti. These genes belong to a pathway called AOI (for autoregulation of infection) by which endosymbiotic bacteria inhibit secondary infection by their rhizospheric peers. We aim to characterize the mechanism underlying AOI in both the plant and microbial partners, with a special emphasis on the signals and pathways involved.

Experimental evolution of the plant pathogen Ralstonia solanacearum into a legume symbiont

Rhizobia do not form a homogenous group but are phylogenetically disparate α- and β- proteobacteria that have achieved a nitrogen-fixing symbiosis with legume. How rhizobia have emerged is a fascinating, but only partly documented, question. Ample evidence supports the view that rhizobia have evolved through horizontal transfer of key symbiotic functions into diverse soil bacteria followed by subsequent recipient genome adaptation under selection in the host plant environment. To experience this evolutionary scenario we have launched an evolution experiment aiming at converting a soil bacterium into a legume symbiont. A chimeric Ralstonia strain was engineered by introducing the symbiotic plasmid of the β-rhizobium model Cupriavidus taiwanensis into the plant pathogen Ralstonia-solanacearum. This chimeric strain is being evolved under legume (M. pudica, the host plant of C. taiwanensis) selection pressure to activate and/or improve competitiveness in nodulation, infection, bacterial maintenance in infected cells and tentatively nitrogen fixation. This project exploits the recent advances in fast genome re-sequencing technology to track genome modifications, both R. solanacearum and C. taiwanensis being completely sequenced. Genomic, cellular and molecular genetics approaches are combined to elucidate the underlying genetic basis of symbiotic adaptation. This project is at the interface of symbiosis and pathogenesis.

Shaping new bacterial symbionts

Collaborations

Our collaborators on the "signalization through cAMP-AOI" project are C. Gough and F. Maillet (LIPM), V. Poinsot (IMRCP) and V. Morales/P. Polard (LMGM).

Our main collaborators on the "experimental evolution" project are D. Roche (Genoscope-CEA Evry), E. Rocha (Pasteur Institute Paris) and A. Jauneau (Imaging platform Toulouse)

 Current fundings

ANR REPLAY (2017-2020) Replaying the evolution of rhizobia: towards a conceptual and practical framework for the design of new nitrogen-fixing plant symbionts. Partners: Genoscope (D. Roche), IP Paris (E. Rocha), 460 k€.

ANR AOI (2016-2019) Autoregulation of infection in the rhizobium-legume symbiosis. Partners LIPM (C. Gough) IMRCP UMR 5326 CNRS Univ Toulouse III  (V. Poinsot). 434 k€