Tree seedling genetics structure soil microbiome communities

Summary:1) The influence of soil microbial communities on the performance of forest trees is well-established, while less is known about how individual trees structure the same communities. We investigated the soil microbiome of the seedlings of a foundation tree species to explore the extent to which soil microbial communities differed between plant genotypes.2) We tested the hypothesis that plant genotype would structure soil microbial communities using a common garden containing recently-established pinyon pine (Pinus edulis) seedlings which exhibit genetically-based drought tolerance or intolerance. Soil cores were collected at the base of 19 seedlings from each drought tolerance category and soil microbial community data was obtained using Illumina sequencing of rRNA gene PCR amplicon pools for bacterial, archaeal, and fungal communities. qPCR was used to assess differences in target gene abundance.3) Alpha diversity and rRNA gene abundance were similar in soils of drought tolerant and drought intolerant seedlings. Drought tolerant seedlings had higher relative abundances of two mycorrhizal fungal genera, while drought intolerant trees were associated with more xerotolerant nonmycorrhizal fungi. Several bacterial taxa also differed between genotypes, though overall beta diversity was similar.4) Our data demonstrate that tree genotype significantly influenced soil microbial communities, even in young plants with a relatively small footprint in the soil. Pronounced differences were present in microbial taxa known to influence plant growth, suggesting rapid establishment of plant-soil relationships.