The arbuscular mycorrhizal (AM) symbiosis as a tripartite association: understanding the recruitment mechanisms among plants, AM fungi and their associated soil microbes

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The root-associated microbiome is a key determinant of soil nutrient availability, plant biomass productivity and pollutant degradation, but could not be examined in depth prior to recent advances in high-throughput sequencing and bioinformatics. Plan root-associated microbiome refers here to the whole community of bacteria and fungi living on the surface and/or inside plant roots. Arbuscular mycorrhizal fungi (AMF) constitute a widespread soil fungal group, which establishes symbiotic associations with the majority of vascular plants. Once AMF colonize plant roots, they develop an extraradical hyphal network, promote nutrient uptake, in particular phosphorus and nitrogen, and protect plants against soil-borne pathogens. As fungi that extend their hypha into the rhizosphere and the surrounding soil, AMF not only interact with plants, but also with a myriad of soil microbes. Several in vivo and in vitro studies have showed that a large range of bacterial species are living on the surface and/or inside mycelia, spores and intraradical propagules of AMF. Some fungal taxa have also been reported to be associated with AMF mycelia. My research program aims to understand and decipher the tripartite interaction of AMF with their host-plant and their associated microbes in nutrient cycling with a particular focus on AMF biology. To that end, my lab will examine the following specific fundamental questions in AMF biology: - How do AMF recruit their associated microbes? - What are the factors that influence the community structure of these associated microbes? - What are the mechanisms by which AMF filter microbial communities? - Do horizontal gene transfers occur between AMF and their associated microbes? - Do AMF have a circadian rhythm that is synchronized with plants rhythmic oscillations? Using a combination of in vitro and in vivo experiments, omics and bioinformatics approaches, my research team will seek to unravel the molecular mechanisms involved in such tripartite interaction with AMF-host plant-soil microbes. My proposed research program will train HQPs in a multidisciplinary and multicultural environments and it will lead to a better understanding of soil microbial ecology and nutrients cycling. It will also yield fundamental insights into plant-microbe interactions and expand our knowledge of symbiotic organisms. AMF play an important role in soil biology. These ubiquitous fungi exist in almost any soil and play a central role in the functioning of ecosystems by forming mycorrhizae with more than 80% of plant species. The understanding of their biology is therefore a key factor in strategies to modify agricultural practices and enhance a perspective for sustainable agriculture. Graduate students engaged in the proposed work will receive excellent interdisciplinary training in genomics, bioinformatics and soil microbiology.