Labex ARBRE

Fungi provide relevant ecosystem services contributing to primary productivity and the cycling of nutrients in forests. These fungal inputs can be decisive for the resilience of Mediterranean forests under global change scenarios, making necessary an in-deep knowledge about how fungal communities operate in these ecosystems. By using high-throughput sequencing and enzymatic approaches, we studied the fungal communities associated with three genotypic variants of Pinus pinaster trees, in 45-year-old common garden plantations. We aimed to determine the impact of biotic (i.e., tree genotype) and abiotic (i.e., season, site) factors on the fungal community structure, and to explore whether structural shifts triggered functional responses affecting relevant ecosystem processes. Tree genotype and spatial-temporal factors were pivotal structuring fungal communities, mainly by influencing their assemblage and selecting certain fungi. Diversity variations of total fungal community and of that of specific fungal guilds, together with edaphic properties and tree's productivity, explained relevant ecosystem services such as processes involved in carbon turnover and phosphorous mobilization. A mechanistic model integrating relations of these variables and ecosystem functional outcomes is provided. Our results highlight the importance of structural shifts in fungal communities because they may have functional consequences for key ecosystem processes in Mediterranean forests.

Filamentous fungi genome sequencing began in the early 2000s and there are currently 1204 fungal genomes deposited in the NCBI database. The mycorrhizal species genome was sequenced during the Mycorrhizal Genome Initiative project. We initially identified the general features of basidiomycete ectomycorrhizal genome species. To gain information on Ascomycete ectomycorrhizal genome species, the sequencing of Pezizomycetes genomes, such as truffles, is ongoing. To date, sequencing of the Tuber aestivum and T. magnatum haploid genomes is complete. Genome sequencing of T. brumale, T. borchii, T. canaliculatum, T. dryophilum, T. excavatum, T. gibbosum, T. indicum, T. lyonii, T. macrosporum, T. maculatum, T. oregonense, and T. rufum will be performed in 2016–2017. A population genomic project was completed by resequencing T. melanosporum geographic isolates, which identified single nucleotide polymorphism resources and traced specific genome evolution. Comparative and population genomic studies provided a better understanding of the main features of truffles, such as their particular organoleptic qualities, evolution, and adaptation to environmental stresses.