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What are you working on?

We live in a symbiotic world. Mutual associations exist in all ecosystems, but it is also important to note that no species evolves alone. Understanding how mutualist, parasitic and commensal associations evolve and sustain themselves on the ecological and evolutionary scale is the key to future progress in medicine or in agriculture. This is the general topic that we explore in my team.

In recent years, my team has been working on leaf symbiosis as a model of interaction between plants and their microbiota. Some families of tropical plants form specific associations with bacteria that manifest themselves by the formation of visible galls or nodules on the leaves. Rare in plants and in opposition to root symbioses, these bacteria, although extracellular, are transmitted in a hereditary way and are sometimes even obligatory for the development of their host!

Our recent work has shown that foliar symbioses have in common the production of secondary metabolites. Indeed, symbiotic Burkholderia bacteria of Psychotria or Ardisia evolved protective functions by the synthesis of large quantities of insecticidal compounds.

It is by studying thesse particularly intimate symbioses that we hope to discover how plants select their mutualistic bacteria at the level of aerial tissues. To do this, we combine genomic, metagenomic, genetic and biochemical approaches.

How attaractive was the TULIP package for you and how does it help you to settle down?

The support of TULIP was decisive in my decision to join the LIPM in Toulouse. Before being recruited at INRA, I was a professor at the University of Ghent, Belgium, where I headed a small team of four PhD students. The logistical and financial aspects of moving an international research team are not simple, even within Europe. Ensuring a smooth transition without penalizing non-permanent staff would probably not have been possible without the support of TULIP. The TULIP package allows me to financially support the projects of doctoral students who follow me in this new Toulouse adventure, but will also allow me to consolidate my team by recruiting new staff.

What are your future projects?

The disadvantage of the symbiotic systems we have studied so far is that they are difficult to manipulate in the lab, our plants having long life cycles and bacteria being difficult or not at all cultivable. We have recently discovered a new bacterial foliar symbiosis in a species of wild yam that is  well adapted to experimental work. My immediate plans are therefore to establish this new system as a model not only of foliar symbiosis with nodules, but as a simple binary model for the study of plant-endophytic bacteria interactions. This new model will also allow to establish which traits are necessary for the evolution of heritable symbioses in plants.

The Toulouse scientific landscape - and the LIPM in particular - are ideal to carry out this project at the interface between plant biology and microbiology. It is also a risky project because it is based on species whose biology is poorly known. Again, the TULIP package allows me to undertake projects that are difficult to finance with other calls for proposals.