Plant roots are inhabited by a diversity of microorganisms known to be key drivers of plant growth and health. Although the rules governing root microbiota assembly have been investigated and the importance of abiotic determinants highlighted, the consequences of the biotic context of the plant community have often been overlooked. We tested the hypothesis that the abundance of species in a given plant neighborhood could leave a fingerprint on its root-endophytic fungal community, ultimately impacting its biomass. Outdoor experimental mesocosms, comprising a range of floristic compositions and spatially mapped plant distributions, were monitored for 2y. Medicago truncatula was used as trap-plant and grown under standardized conditions on soil samples collected in the mesocosms. The root-endophytic fungal community of M. truncatula was described by amplicon mass sequencing and M. truncatula performance was also assessed. The richness and evenness of M. truncatula's root-endophytic fungal community were explained by the small-scale plant neighborhood of the soil samples. For instance, the occurrence of Brachypodium pinnatum in the neighborhood induced higher and lower richness of Sordariomycetes and Glomeromycetes, respectively, whereas Holcus mollis decreased the OTU evenness of the entire mycobiota. These changes in fungal clade OTU richness and evenness were related to modifications in the biomass of M. truncatula. These results indicate that a given plant endophytic fungal community is determined in part by the neighboring plants. Considering that changes in endophytic fungal community are correlated with the plant biomass, this suggests that plant-plant interactions (i.e. competition, facilitation) impacting plant biomass can be mediated by endophytic fungal community changes.

植物根部栖息着多种微生物，这些微生物被认为是植物生长和健康的关键驱动因素。尽管已经研究了控制根微生物群落装配的规则，并强调了非生物决定因素的重要性，但植物群落生物环境的后果常常被忽略。我们测试了以下假设：给定植物邻里中的丰富物种可能在其根-内生真菌群落上留下指纹，最终影响其生物量。监测包括2个植物区系组成和空间分布的植物分布的室外实验中观。紫花苜蓿用作捕集植物，并在标准化条件下在中观收集的土壤样品上生长。通过扩增子质量测序描述了截叶分枝杆菌的根-内生真菌群落，并且还评估了截叶分枝杆菌的性能。truncatula根内生真菌群落的丰富性和均匀性可以通过土壤样品的小规模植物邻域来解释。例如，发生羽状短柄草在附近分别诱导和粪壳菌纲Glomeromycetes，较高和较低的丰富性，而Holcus mollis的降低了整个真菌菌群的OTU均匀度。这些真菌进化枝OTU的丰富度和均匀度的变化与截枝芒的生物量的改变有关。这些结果表明，给定的植物内生真菌群落部分地由邻近植物决定。考虑到内生真菌群落的变化与植物生物量相关，这表明影响植物生物量的植物-植物相互作用（即竞争，促进）可以通过内生真菌群落的变化来介导。