A symbiotic footprint in the plant root microbiome

A major aim in plant microbiome research is determining the drivers of plant-associated microbial communities. While soil characteristics and host plant identity are important drivers of the root microbiome, it is still unexplored whether the presence or absence of important plant root symbionts determine microbiome composition. We profiled the root microbiome of 17 plant species differing in their symbiotic associations with rhizobia and arbuscular mycorrhizal fungi and tested the hypothesis that symbiosis types define root microbiome diversity and composition. We discovered that symbiotic association is a significant driver of root microbiome diversity and revealed taxonomic patterns of OTUs that were characteristic for the different symbiosis groups. Our results reveal that symbiotic associations of the host plant leaves an imprint on the wider root microbiome – which we term the symbiotype – and highlight the existence of a fundamental assembly principle of root microbiomes, dependent on the symbiotic associations of the host plant.