Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie

Purpose

Shelf life

CAS and PHP session cookies

Login credentials, session security

Session

Tarteaucitron

Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie

Purpose

Shelf life

atid

Trace the visitor's route in order to establish visit statistics.

13 months

atuserid

Store the anonymous ID of the visitor who starts the first time he visits the site

13 months

atidvisitor

Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at cil-dpo@inrae.fr or by post at :

INRAE

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

Last update: May 2021

Menu Logo Principal

Home page

Zone de texte éditable et éditée et rééditée

Topic 1 - Multi-scale host-pathogen adaptation: host specialization and response to qualitative and quantitative resistances

flag-fr

The use of wheat resistant varieties, one of the most effective methods of protection against fungal pathogens, is often not sustainable in current cropping systems due to their high adaptive capacity at the population level. Our research aims to understand how pathogen populations adapt to the genetic resistance of heterogeneous host populations. We address the following questions: How does the fungus adapt to its host (e.g. bread wheat, durum wheat and triticale) and to its resistances?, How to reintroduce an effective level of functional diversity into crops at plant, plot and regional scales?, How to integrate quantitative resistance into management strategies? What is the impact of the adaptation of pathogen populations on the durability of the resistances?

This first axis justifies a strong investment in understanding the impact of quantitative resistance on the evolution of pathogen life-history traits (fitness and aggressiveness). Since some years our research is carried out simultaneously on both plant and pathogen sides: the sources of resistance are characterized through a combined study of the genetic architecture of the host resistance and of the pathogenicity of the fungus (Zymoseptoria triticiPuccinia triticina).

Most of our activities are still based on long-term survey of pathogen populations in natural conditions and acquisition of phenotypic data (pathotyping and race identification, quantification of aggressiveness traits, resistance gene postulation). This is particularly the case for annual monitoring in P. striiformis and P. triticina, with a summary report sent each year to plant breeding companies and ARVALIS-Institut du Végétal. Our collection of rust isolates, stored at -80°C, constitutes an extremely rich and unique database (core collection of several hundred P. triticina and P. striiformis reference isolates collected annually since the mid-1990s, completed by an historical work collection of thousands isolates). A more recent collection of Z. tritici (worldwide and local subpopulations) is also being constructed. These collections are used in several projects conducted at various scales:

Gene scale

In order to understand how pathogen populations adapt to qualitative and quantitative wheat resistances, we characterize and genetically map resistance genes from the host and pathogenicity genes from the pathogen. This work was performed on P. triticina within Gustavo Azzimonti's PhD thesis and several MSc students. Most of our activities are focused on screening different variety panels of bread and durum wheats, developing new phenotyping methodologies, constructing linkage maps to identify QTL involved in quantitative resistance, and performing GWAS analyses to identify host resistance and pathogen aggressiveness loci. This important experimental work, essential for evaluating the durability of wheat resistance, is developed on Z. tritici for some years now. Consensus linkage maps comprising several thousand SNP markers were built for bread and durum wheat allowing the identification and comparison of robust quantitative resistance QTL to leaf rust and to Septoria leaf blotch. Those QTL are now being fine-mapped to derive diagnostic markers for breeders. GWAS analyses in French Z. tritici populations allowed the identification of several candidate avirulence genes corresponding to known Stb resistance genes. This work, developed in collaboration with ETH Zürich and Université de Neuchâtel allowed to identify and to characterize functionally the first avirulence gene (AvrStb6) in Z. tritici. These research activities continue through a post-doctoral project.

P05
Field scale
P06

Our team has investigated for about thirty years the effectiveness of cultivar mixtures to limit the spread of epidemics within a wheat canopy. While the efficacy has been demonstrated for wind-borne diseases (stripe rust), it was less clear for rain-splashed diseases (septoria leaf blotch). This efficacy was explained by biophysical effect (barrier and dilution of the susceptible host resource). The PhD theses of Christophe Gigot, then of Tiphaine Vidal, focused on the interactions between plant architecture, canopy structure and pathogen dispersal in varietal mixtures, in collaboration with EcoSys. Our team now focuses on the impact of cultivar mixtures on host-pathogen interaction and adaptive dynamics rather than on their architectural effect sensu stricto. The hypothesis developed in the Carolina Torrejon’s PhD thesis is that a varietal mixture could modify the transmission rate of virulence between two cropping seasons through the impact of both asexual and sexual reproduction. In parallel, Safa Ben Krima's PhD thesis aims to characterize the adaptation of Z. tritici to Tunisian durum wheat landraces, known to be genetically heterogeneous at an even smaller scale.

Landscape scale

The team has been interested for several years in optimizing the territorial management of wheat varieties to improve the efficiency and the durability of resistance. We based most of our research activities on our large collection of Puccinia sp. isolates, a corpus of phenotyping data (virulence and aggressiveness), the analysis of the distribution of French cultivars, and the postulation of their resistance genes. We connected, at the national level, the frequency of cultivars to the pathotypic composition of pathogen populations. The theoretical influence of strategies of resistance deployment on the intensity of epidemics and on the evolutionary dynamics of the pathogen (virulence and aggressiveness) was established by Julien Papaïx at the landscape scale during his PhD thesis. He characterized the link between environmental spatial heterogeneity and the adaptive dynamics of pathogen populations. Theoretical models showed for instance that epidemic control could be achieved by altering landscape connectivity. The presence of spatial clusters of habitats in the metapopulation was also found to facilitate specialization and to increase both the level of adaptation and the evolutionary speed of the population when dispersal is limited. Since then, studies have been conducted at the landscape scale in interaction with other BIOGER teams, focusing for instance on the management of fungicide sprays in the Maxime Garnault’s PhD thesis. Our objective is now to improve theoretical models and to validate them with experimental data to understand how host heterogeneity and landscape connectivity influence the intensity of wheat rust epidemics (see Axis 4). In her PhD thesis, as part of the H2020 RustWatch project, Cecilia Fontyn now aims to answer the question "Is aggressiveness a significant component of the adaptation of populations of P. triticina to the cultivated landscape?"

P07