Phylogenetic and environmental controls on the structure of boreal moss microbiomes

What structures moss microbiomes in high-latitude ecosystems–host or environment? High-latitude mosses harbor diverse microbes, including N2-fixers which are key contributors to nitrogen dynamics, but it’s unclear if these microbiomes are shaped more by host or environment. We characterized the microbiomes, environmental factors, and N2-fixation rates of 26 boreal moss species. While host and environment both shaped microbiomes, host evolutionary history was a more useful predictor of microbiome structure. We also identified novel bacteria and host-specific putative N2-fixers outside the well-studied Cyanobacteria. We show that mosses provide new insight into plant-microbe interactions and the roles of moss-microbes in high-latitude ecosystems.