Research topics

The soil-plant-microorganisms interaction in the rhizosphere is a key process that plays a key role in plant growth and health and carbon recycling/storage

1.1 The microbiota mediates interactions between the host and its environment

The plant microbiota plays a key role in plant growth and health. The structure and functions of this microbiota are modulated by the host and the environment. In feedback, the microbiota mediates interactions between the host and the environment.

Our research aims to study the interactions between the host, the microbiota and the abiotic environment in the context of anthropogenic pollution, such as metals (DUNE, PRIMARy) and nanomaterials, and the improvement of plant (ENHANCE, InSTep) and forest (RESTORE) health. https://www.biodiversa.org/1874/download).

Nanotechnologies are a major source of cutting-edge materials that can help the necessary transformation of agriculture in a context of environmental transition, and preservation of resources and the environment (adaptation to climate change, reforestation, reduction in the use of pesticides, etc.).

In the framework of the SERENADE LabEX (Ecodesign Research and Education applied to Nanomaterials, 2012-2020), microbiota from terrestrial and aquatic environments have been used as a tool to improve the knowledge of structure-intrinsic properties/environmental implications of nanomaterials (MEANTime) and to design “safer-by-design” nanomaterials (Safer-by-Design).

Our research aims at understanding how the properties of nanomaterials modulate their interactions with the plant-soil-microbiota system (ANALOGY), allowing the development of nanotechnologies for agriculture (InSTep) and reforestation (RESTORE) through a Safer-by-Design approach.

Our approach integrates the study of social representations of nanomaterials by professionals in agriculture and forest management (RESO-Nano) in partnership with Alexandra Schleyer-Lindenmann and Nelly Pares of the UMR ESPACE (Étude des Structures, des Processus d’Adaptation et des Changements de l’Espace).

1.2 Plant-microbiota molecular dialogue

Interactions between the host and its microbiota rely on sophisticated ways to communicate and coexist. We are interested in the complex and interconnected networks of signals and metabolites that modulate the dialogue between the plant and its microbiota as well as that between the microorganisms themselves to regulate these interactions

In the framework of RootAdapt “Root traits for adaptation of pearl millet to future climate in West Africa“, we aim to identify the assemblage and ecological network of the most influenced microbial populations by the changes in different pearl millet inbred lines exudation and the correlation between these populations with specific metabolic pathways related to diversity of molecules exuded by the roots. 

A better understanding of how the plant responds to phytopathogens versus phytobeneficial bacteria and how the latter potentiate the plant’s defense response to control diseases is addressed by a RNA-Seq approach.

The LEMiRE team has gained experience in exploiting the potential of microbial diversity for sustainable solutions in crop protection against disease and pests in the frame of projects developed with private companies :

• Micro-organisms for Sustainable Agriculture (MOPAD). Biological control agents based on microorganisms to protect common wheat against Fusarium head blight.
• Use of microbial diversity to identify insecticidal activities against the larva of the corn rootworm Diabrotica virgifera virgifera (DIETETIC). Bacterial genomes sequencing and exploration for in silico screening of insecticidal molecules against corn Diabrotica larvae.

Our work aims to study the mechanisms of adaptation to environmental constraints of two bacterial models that represent different modalities of tolerance to stresses related to their habitats.

2-1 Adaptative strategies of phytobeneficial bacteria

2-2 Adaptative strategies of Ramlibacter tataouinensis to extreme environments

A cell cycle under the control of light, contributes to the adaptation of Ramlibacter tataouinensis to the desert and confers tolerance to desiccation and more broadly to conditions encountered in a hot and dry desert. R. tataouinensis is a ß-proteobacterium isolated from fragments of sandy meteorites collected in the semi-desert region of Tataouine (southern Tunisia).

This desert bacterium has the particularity to alter orthopyroxene, a major constituent of meteorites. The high tolerance of this bacterium to extreme desert conditions, and in particular to desiccation, is probably linked to the original cell cycle characterized by the coexistence of coccoid cells surrounded by a protective polymer (presenting all the characteristics of a cyst resistant to desiccation: Ø 0.8 µm) and rod-like cells (Ø 0.2 x 3 µm). The mobility of the rods ensures the dissemination of the population allowing the colonization of new ecological niches. Exploration of the R. tataouinensis genome and experimental evidence suggest the involvement of light via its two bacteiophytochromes and the circadian cycle regulator KaiC in the control of the cell cycle of this bacterium.