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

Menu Institut Sophia Agrobiotech Logo Marque Etat - République Française Logo_INRAE_noir Logo Université Côte d'Azur CNRS

Home page

Institut Sophia Agrobiotech

UMR INRA - Univ. Nice Sophia Antipolis - Cnrs

Nitrate reductases and hemoglobins contribute to nitric oxide (NO) balance in the Medicago truncatula – Sinorhizobium meliloti symbiosis

Friday 9 February - 11:00 - Sophia Antipolis - Inra PACA - Room A010

Séminaire scientifique
As part of the scientific animation of Institut Sophia Agrobiotech, Antoine BERGER, PhD in Symbiose team, will present: "Nitrate reductases and hemoglobins contribute to nitric oxide (NO) balance in the Medicago truncatula – Sinorhizobium meliloti symbiosis"


The symbiosis between legumes and bacteria of rhizobium type leads to the formation of nitrogen-fixing nodules. In the symbiotic model Medicago truncatula/Sinorhizobium meliloti, nitric oxide (NO) is produced throughout the whole symbiotic process, from early interaction between the plant and the bacteria to senescence of nitrogen fixing nodules. Toxic, signalling or metabolic effects of NO depend on its concentration at the site of action. Therefore, NO steady-state concentration inside the cells should be tightly controlled to limit toxic effects and allow the signalling and metabolic functions to occur. In plants, several sources of NO have been described including nitrate reductase (NR), mitochondrial electron transfer chain (ETC) and NOS-like activity. Hemoglobins (Hbs) are known to metabolise NO. Based on their sequence homology and affinity for oxygen, three classes of Hbs have been essentially described in plants: non-symbiotic hemoglobins (ns-Hbs, Class 1), leghemoglobins (Lbs, Class 2) and truncated hemoglobins (tr-Hbs, Class 3). The three types of Hbs were reported to be expressed in legumes.     

To precisely assess the occurrence of NO during the whole symbiotic process, and the respective role of the different NRs and Hbs in its balance, we analysed the production of NO, the expression of 3 NRs and 6 Hb genes, and the global NR activity during short term (0 to 14 days post-inoculation and long term (0 to 8 weeks post-inoculation) symbiosis experiments.

Four peaks of NO production, which levels depend on nitrate concentration in culture medium, were observed 10 hours, 4 days, 3-4 weeks and 6 weeks post-inoculation. NO production was correlated with NR1, NR2, ns-HBs and tr-Hbs genes expression at the different stages of nodule formation. The use of various NO source inhibitors showed that NO production mainly depends on NR activity during early interaction steps as well as in mature and senescent nodules.

The different roles of NO, as a signalling and/or metabolic molecule, and its regulation by NRs and Hbs, in young, mature and senescent nodules are discussed.