Interactions Team

The team is interested in the response of tree cover interacting with other organisms (plants or microorganisms) subject to fluctuating water and nitrogen availability in soil (Figure 1). It takes a holistic approach that integrates plant ecophysiology (particularly in relation to nitrogen nutrition) and ecogenomics, the metagenomics of associated microbial communities, and the physicochemistry of the aerial and underground microenvironment.

Figure 1. Projet d'équipe

Context

Climate change is characterized by an increase in extreme weather events that profoundly affect the development and, de facto, the production performance of cultivated plants. Among these environmental constraints, fluctuations in the availability of water (due to more pronounced rainfall patterns) and mineral nitrogen (correlated with soil water availability and also modified by human activity) represent one of the major challenges for agriculture and forestry. In a context of recurring climate hazards and agro-ecological transition, crop diversification not only improves plant production but also enhances associated biodiversity and several supporting and regulating ecosystem services. These performances result from biotic interactions between plants and their microbial environment, which determine access to environmental resources (radiation, water, nitrogen), and vice versa. However, these interactions are not always beneficial: they can accentuate competition for access to these resources. It therefore seems relevant to explore in greater detail the underlying molecular mechanisms, as well as their temporal and spatial dynamics in relation to the ecophysiology of interacting plant species.

Objectives

The team has set itself the goal of studying the ecophysiological and ecogenomic response of trees to water stress in interaction with other plants and microorganisms, as observed in agroforestry or forest environments. The team thus aims to contribute to improving understanding of how trees function in their environment with a view to identifying potential solutions for sustainable agriculture and (agro-) forestry management in the face of climate challenges. This objective will be addressed through two  actions: (1) Characterizing the efficiency of water and nitrogen use by trees under water and nitrogen stress and in interaction with other plant species in mixed stands, and (2) Identifying rhizosphere and root microbial communities and their putative functions in relation to the ecophysiological and ecogenomic response capacity of trees under water stress. One of the envisaged applications is the development of biostimulation solutions using candidate microorganisms to make tree cover more resilient to fluctuating water and nitrogen availability conditions.

Experimental approaches

The research approach is based on three key elements:

• controlled experimentation: availability of a network of greenhouses on the University site (Cézeaux and Aurillac campus) and at INRAE (Crouël),
• network of in situ plots: partnership with technical institutes and chambers of agriculture specializing in temperate (CTIFL, Drôme Chamber of Agriculture) and tropical (French Rubber Institute) agroforestry,
• modeling: use of the RReShar model developed within the Capsis modeling database,

Beyond the devices themselves, the available tools and the expertise required for their use and data analysis enable the ecophysiological (Licor-6800, isotope (¹⁵N), dendrometer, Cavitron, cryostat, pressure chamber, psychometer, drought box), biochemical, and molecular characterization of the trees' response, as well as the physicochemical characterization of their microenvironment (radiation, temperature, and humidity sensors in the air, soil, and organs).

Ongoing national and international collaborations allow the team to address its research question in relation to issues raised by stakeholders in production sectors through reserach projects such as:

• Fertim: Improving fertility and NPK fertilization in rubber trees through agroecological management (Partner: French Rubber Institute)
• AgriAuRA20250: Climate Change and Agroecological Transition (Partners: Regional Chamber of Agriculture, CTIFL),
• PEPIT AGROFOREST: Exploring ecosystem services in multi-sector agroforestry plots across the Auvergne-Rhône-Alpes region (Partner: Regional Chamber of Agriculture),
• MaFHé: Foliar diseases of rubber trees (Partner: French Rubber Institute, CIRAD-AGAP),
• PhD thesis funded by IRC-SAE on the effect of tree cover on microclimate: a tool for mitigating climate change impacts climate change (Partner: Forest National Board).

Some notable publications

Larissa Adamik, Philippe Balandier, Jean-Stéphane Venisse, Marine Fernandez, Philippe Malagoli. Water-based root exudates of Molinia caerulea (L.) Moench disrupt root nitrogen metabolism in Quercus petraea (Matt.) Liebl. seedlings with a fast negative effect on budburst. Annals of Forest Science, 2025, 82 (1), pp.31. ⟨hal-05267771⟩

Marine Fernandez, Philippe Malagoli, Lucie Vincenot, Antoine Vernay, Thierry Ameglio, et al.. Molinia caerulea alters forest Quercus petraea seedling growth through reduced mycorrhization. AoB Plants, 2022, 15 (2), plac043. ⟨hal-03977500⟩

Marine Fernandez, Antoine Vernay, Ludovic Henneron, Larissa Adamik, Philippe P. Malagoli, et al.. Plant N economics and the extended phenotype: Integrating the functional traits of plants and associated soil biota into plant‐plant interactions. Journal of Ecology, 2022, 110, pp.2015-2032. ⟨hal-03694422⟩

Lucas Mazal, Alex Fajardo, Irène Till-Bottraud, Dov Corenblit, Boris Fumanal. Kin selection, kin recognition and kin discrimination in plants revisited: A claim for considering environmental and genetic variability. Plant, Cell and Environment, 2023, 46 (7), pp.2007 - 2016. ⟨hal-04243901⟩