Plant-plant interactions mediated by fungi impact plant fitness. plant diversity-productivity relationship extended to the root microbiota

The plant microbiota, and especially the fungal compartment, is now recognized as a major driver of plant health. The rules governing root microbiota assembly have been recently investigated and the importance of abiotic determinants, such as soil properties, has been highlighted. The role of the biotic context of the plant community however remains unclear. We tested whether the plant neighborhood could leave a fingerprint on the fungal soil pool, ultimately impacting plant health. We used outdoor experimental mesocosms comprising a large range of floristic composition and mapped plant distribution over two years. Medicago truncatula was used as a trap plant on soil samples and root DNA was sequenced to describe the fungal communities. The biomass of the trap plant was finally measured.Our results suggest the existence of plant-plant interactions mediated by fungi and impacting plant fitness. The shift between facilitation and competition may be mediated by the fungal community. The ecosystem diversity-productivity relationship may be extended to the root microbiota and depend on the plant community context.