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:

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:, 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

Google Analytics

Targeted advertising cookies


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 or by post at:

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

Dernière mise à jour : Mai 2018


Laboratory of Plant-Microbe Interactions - LIPM

Laboratory of Plant-Microbe Interactions

Research themes - Rhizobia, legumes and environment

The general stress response in Sinorhizobium meliloti

The general stress response has been well studied in Escherichia coli: in response to various stress conditions, the alternative sigma factor sigmaS accumulates and permits the RNA polymerase to transcribe hundreds of new genes, some of which are involved in stress adaptation. This allows bacteria to survive not only the stress they currently experience, but also many other stresses that they could potentially face in the future, in particular in periods of prolonged nutrient starvation. This multiple and preventive protection is believed to be of primary importance for the survival of bacteria in nature. However, no sigmaS orthologue is encoded in the genome of S. meliloti and other a-proteobacteria.

For the first time, we identified the σ factor RpoE2 as a major regulator of the general stress response in S. meliloti (Sauviac et al. 2007). Indeed, in response to various stress conditions, RpoE2 controls the expression of >45 genes including stress resistance genes. Interestingly, RpoE2 orthologues are widely distributed among α-proteobacteria where they play various roles in stress adaptation and/or host colonization, which suggests they are the long-searched functional analogs of E. coli sigmaS. We more recently characterized the mechanism of activation of RpoE2 in response to stress. A complex model was proposed, involving 2 anti-sigma and 2 anti-anti-sigma factors working together in a partner-switching cascade (Bastiat et al. 2010).

Our present objectives are i) to better characterize the RpoE2-dependent response, in particular the mechanisms of stress perception and signal transduction, ii) to better understand the physiological functions of the RpoE2-dependent response, iii) to identify other regulators of the general stress response in S. meliloti.

Study of the NO response in Sinorhizobium meliloti

NO (nitric oxide) plays a key role in intracellular signaling in eukaryotic cells. In animal as well as in plant cells NO at toxic concentration is also part of the anti-bacterial arsenal against pathogens. Surprisingly, several indications of the occurrence of NO during legume–rhizobia interactions have also been reported, and recently NO was detected in M. truncatula nodules infected by S. meliloti. On the other hand, NO is also produced in the soil by denitrifying bacteria. In both cases, this toxic molecule may represent a stress for S. meliloti and it is interesting to understand how rhizobia cope with the presence of NO and what role is played by the bacterial NO response in the interaction with the host plant. Using a transcriptomic approach on bacteria in free living conditions, we identified about 100 genes induced by NO, and two major transcriptional regulators (FixLJ and NnrR) involved in this response (Meilhoc et al. 2010). We showed that one of the genes belonging to the NO stimulon, hmp, encodes a flavohemoglobin involved in NO detoxification in S. meliloti. By using hmp as a tool to modulate the NO level in planta we established a dual role for NO: positive on the early steps of symbiosis and negative on nitrogen fixation efficiency (del Giudice et al. 2011).

Our present objectives are i) to decipher the role of the bacterial response to NO in symbiosis ii) to characterize NO role(s) at the different steps of the symbiotic process.

Current fundings

  • ANR STAYPINK 2016-2019 (Coord. C. Bruand)
  • TULIP New Frontiers 2016-2018 (B. Gourion)
  • INRA SPE 2016-2019 (B. Gourion)
  • ANR Trolesinfidels 2018-2022 (B. Gourion)
  • FRAIB ILUMINER 2018-2020 (JM. Couzigou LRSV/B. Gourion LIPM)