TEAM IMR - Interactions Multitrophiques dans la rhizosphère

Team Leader : Philippe LEMANCEAU

Research conducted within the group addresses multitrophic interactions in the rhizosphere between plants, bacteria and fungi (mutualists and phytopathogens) in order to promote plant growth and health.

More specifically, our project aims at analyzing (i) the plant effect on associated microbiota (structure, diversity and activity) and in turn (ii) the influence of this microbiota on the host-plant. The challenge of the corresponding research is to monitor the rhizosphere microbiota via the host-plant by promoting beneficial populations and therefore valuing plant rhizodeposits.

Research on rhizosphere microbiota are conducted at different levels of organization: community, population and organism.

-          Works on communities aim at identifying plant functional traits associated with nitrogen cycle that impact the structure and diversity of the rhizosphere microbiota. Two approaches are followed, the first consists in comparing the impact of different plant genotypes on the bacterial metagenome of the corresponding rhizospheres, the second consists in assessing the effect of different plant combinations on the taxonomic bacterial diversity and abundance of functional communities associated with N cycle. The researches on plant combinations are conducted in collaboration with Delphine Moreau and Laurent Philippot from EcolDur Team.

-          Works on populations and organisms are carried out on fluorescent pseudomonads and aim at characterizing populations beneficial for the host-plant and at deciphering underlying mechanisms at the molecular and cellular levels. Two bacterial traits particularly relevant for interactions with eukaryotes (plants and fungi) are analyzed: siderophore production involved in bacterial iron uptake and Type Three Secretion Systems (TSS3) involved in cell-to-cell communication between prokaryotes and eukaryotes. The strategy followed consists in analyzing the diversity of pseudomonad populations and of the above-referred traits in connection with their biological activities. These activities include (i) for siderophores, antagonism against phytopathogens and plant iron nutrition, and (ii) for T3SS, plant-fungal interactions (mycorhization, plant defense reaction). Mechanisms involved in the contribution of siderophore and T3SS in plant-bacterial interactions are analyzed at the cellular and molecular levels (optical and electron microscopy, laser microdissection microscopy).

Studies on siderophores are conducted in close connection with the group ‘NO and plant defense reaction of the plant’ led by David Wendehenne from IMP Team.

Corresponding research rely on the strong support of the Unit platforms: GenoSol, Microscopy and Serres-PPHD.