CERES
Centre de formation sur l’environnement et la société

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Towards an agro-ecological theory of plant-pathogen interactions – application of evolutionary ecology to agro-ecosystems

2012-2013. Financement : ENS (Projet incitatif de recherche).

Participants : Corinne Robert (INRA-AgroParisTech UMR 1091 Environnement et Grandes Cultures EGC), David Claessen (ENS, CERES-ERTI), Christian Fournier (INRIA Virtual Plant, INRA Laboratoire d’Ecophysiologie des Plantes sous Stress Environnementaux UMR LEPSE), Thomas Tully (UMR 7625 Ecologie & Evolution CNRS-ENS-UPMC, IUFM)

Project

The central idea of “agro-ecology” is to study the ecological principles that underlie the dynamics and processes within agricultural ecosystems, referred to as agro-ecosystems (Wezel et al 2009). A better understanding of these ecological processes can be used to exploit these processes in order to manage the agro-ecosystems, e.g., for increasing productivity or for reducing the use of chemical products to control pests and weeds. Here we propose to use evolutionary-ecological theories to study the problem of crop plant disease and epidemics, which are a major problem to agriculture globally, representing a significant loss of annual yields. We will study plant-pathogen interactions from the point of view of evolutionary ecology.

Agriculture today faces a tough challenge : reducing chemical inputs (pesticides, fertilisers) while at the same time increasing productivity. For example, in France the objective is to reduce fungicide use by 50% by 2018 (Grenelle de l’environnment, Plan Ecophyto 2018). A novel approach to reach this goal is to use the plant’s own characteristics to regulate epidemics (Robert et al 2008). Until now, the objective of agricultural practices has been to eradicate the pathogens using pesticides or full plant resistance. However both solutions are unsustainable (due to pollution and to pathogen adaptation to the plant’s resistance). A new approach is currently emerging, referred to as agro-ecology, which aims to regulate the pathogens through considering the plant-pathosystem as an ecological system. Until now crops have been fertilised without consideration of the effect on pathogens. It has emerged, however, that strong nitrogen fertilisation can reinforce epidemics. We will use ecological theories to better understand the interactions between pathogens and their plant host for different levels and types of resources and different types of pathogens. We will characterise the plant-pathogen interactions in terms of concepts from optimal foraging theory (MacArthur and Pianka 1966), consumer-resource dynamics (Murdoch et al 2003) and ecophysiology (Lambers et al 2008), and use these theories to describe the dynamics of the within-plant nutrient components, in conjunction with the dynamics of the pathogen population, subject to specific external forcing. The external forcing corresponds to different agricultural practices.


References
Lambers, H., Chapin, F. Stuart, P., Thijs L. (2008). Plant Physiological Ecology, Second Edition. Springer.
MacArthur, R. H. and E. R. Pianka. (1966). On optimal use of a patchy environment. American Naturalist 100 : 603-609
Murdoch, W.W., Briggs, C.J. & Nisbet, R.M. (2003) Consumer–Resource Dynamics. Princeton University, Press, Princeton, NJ.
Robert C. Fournier C. Andrieu B., Ney B. 2008. Coupling a 3D virtual wheat plant model with a Septoria tritici epidemic model : a new approach to investigate plant-pathogen interactions linked to canopy architecture. Functional Plant Biology, 35/9-10:997-1013
Tully, T., Ferrière, R. (2008) Reproductive flexibility : genetic variation, genetic costs and long-term evolution in a collembol. PLoS One, 3, pe3207
Wezel, A., Bellon, S., Doré, T., Francis, C., Vallod, D., David, C. (2009). Agroecology as a science, a movement or a practice. A review. Agronomy for Sustainable Development 29 (2009) 503-515 (http://dx.doi.org/10.1051/agro/2009004)