# More Than a Stick in the Mud: Eelgrass Leaf and Root Bacterial Communities Are Distinct From Those on Physical Mimics

## TL;DR

Eelgrass leaves and roots host unique microbial communities distinct from physical mimics, suggesting biotic interactions shape these microbial ecosystems.

## Contribution

The study identifies distinct microbial taxa associated with eelgrass leaves and roots, linked to plant-microbe interactions and environmental stress mitigation.

## Key findings

- Eelgrass leaves host microbes linked to algal disease, suggesting potential roles in plant-microalgal interactions.
- Root-associated microbes are involved in sulfur and nitrogen cycling, possibly aiding plant stress tolerance.
- Microbial communities on eelgrass differ significantly from those on physical mimics, indicating host-specific interactions.

## Abstract

We examine the role of physical structure versus biotic interactions in structuring host‐associated microbial communities on a marine angiosperm,
Zostera marina
, eelgrass. Across several months and sites, we compared microbiomes on physical mimics of eelgrass roots and leaves to those on intact plants. We find large, consistent differences in the microbiome of mimics and plants, especially on roots, but also on leaves. Key taxa that are more abundant on leaves have been associated with microalgal and macroalgal disease and merit further investigation to determine their role in mediating plant–microalgal–pathogen interactions. Root associated taxa were associated with sulphur and nitrogen cycling, potentially ameliorating environmental stresses for the plant. Our work identifies targets for future work on the functional role of the seagrass microbiome in promoting the success of these angiosperms in the sea through identifying components of microbial communities that are specific to seagrasses.

Unique communities inhabit eelgrass leaves and roots compared to physical mimics and their environment. We examine which taxa vary to determine what host–microbe relationships may be mediate by biotic interactions. This indicates that eelgrass leaves and roots may just unique environments for microbes, but also could indicate more active partnership/inhibition involved in the host–microbe relationship worthy of further exploration.