Poster presentation at the ISS Holobiont meeting 2022 in Lyon!

Characterization of root-associated microbiota of non-mycorrhizal plants and its contribution to phosphorus nutrition

Authors: P. Bruyant, J. Doré, Y. Moënne-Loccoz, J. Almario

UMR CNRS 5557 Ecologie Microbienne, Université Claude Bernard Lyon1, 43 Boulevard du 11 novembre 1918, 69622 Villeurbanne, France

Most land plants rely on the arbuscular mycorrhizal symbiosis for their phosphorus (P) uptake. However, there are non-mycorrhizal (NM) plant lineages (e.g. Brassicaceae, Cyperaceae and Caryophyllaceae families) that lost the ability to establish this symbiosis and it is still not clear how these plants acquire enough P to grow, especially in P-depleted soils. Recent studies suggest a potential role of newly-discovered fungi in the P nutrition of these NM plants. Indeed, it was shown that some fungi, phylogenetically distant from mycorrhizal lineages (e.g. Helotiales strain F229, Colletotrichum tofieldiae, Serendipita indica) have mycorrhizal-like features, including enhancing plant P acquisition by transferring P directly from the substrate to Brassicaceae NM species. However, the contribution of these “mycorrhizal-like” fungi to P nutrition of NM plants remains unexplored. We put forward the hypothesis that mycorrhizal-like fungi functionally replace arbuscular mycorrhizal fungi in NM plants, contributing significantly to the P nutrition of these plants. We conducted a large-scale analysis (using ITS2 metabarcoding) of the fungal root microbiota of 39 wild-growing NM and mycorrhizal plant species, along a gradient of soil P concentrations, to have a first characterization of the microbiota of these plants and identify their specificities. We will also present correlation data between P acquisition of NM plants and the composition of the fungal microbiota with the aim to pinpoint potential mycorrhizal-like taxa. Our final goal is to quantify the contribution of these fungi to the P nutrition of NM plants and determine if these associations could be a new adaptation balancing the loss of the mycorrhizal symbiosis in NM plants.