Stéphane Firmin, deputy director of the AGHYLE research unit and a faculty member and researcher in Toxicology and Chemical Risks, successfully defended his thesis for the [HDR] qualification. The defense took place on Tuesday, October 27, 2026, at UniLaSalle Beauvais.
Plasticity of Communication Networks in the Plant Holobiont: Toward an Integrative Framework Linking Soil Health and Human Health
Jury
- Sylvie Baltora-Rosset, Professor, Jules Verne University of Picardy
- Christian Mougin, Research Director, INRAe Versailles
- Simon Labarthe, Research Director, INRAe Bordeaux
- Philippe Laval-Gilly, Professor, University of Lorraine
- Franck Vandenbulcke, Professor, University of Lille
Abstract
Today, toxicology and agroecology share common scientific challenges related to understanding the effects of human activities on living organisms, their interactions, and, more broadly, the functioning of ecosystems (habitats). However, the integration of these disciplines remains limited, even as environmental and health challenges call for more systemic and interdisciplinary approaches. This thesis is part of this trend, proposing a scientific path at the intersection of environmental health, functional ecology, and the study of plant–microbiome interactions. Its central theme is the analysis of the effects of chemical contaminants on biological systems, ranging from molecular mechanisms to the functioning of agroecosystems.
The first part of this thesis discusses my main achievements in characterizing chemical hazards to human and animal health through the study of the fate of contaminants in food and environmental matrices, their mechanisms of action, and their contribution to the emergence of chronic diseases. Gradually, this research expanded to include the study of interactions between living organisms and their abiotic environment in agroecosystems, focusing on the study of rhizodeposition.
This development leads us to view biological systems as dynamic systems in which the response to contaminants arises from the interaction between the host, associated microbial communities, and the physicochemical characteristics of the environment.
With this in mind, my research project aims to better understand how soil properties influence plant production and rhizodeposition, as well as the nature of the molecular signals they convey. More specifically, this work seeks to identify the mechanisms that determine the resilience of the soil–plant system in the face of environmental stresses and promote the transition toward more sustainable agriculture. Beyond its agronomic applications, this research initiative contributes to a broader discussion on the evolution of chemical risk assessment methods. It leads to the proposal of a holistic approach that integrates interactions between organisms, microbiomes, and the environment within a One Health framework.
