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Abstract Host‐associated microbes influence host health and function and can be a first line of defence against infections. While research increasingly shows that terrestrial plant microbiomes contribute to bacterial, fungal, and oomycete disease resistance, no comparable experimental work has investigated marine plant microbiomes or more diverse disease agents. We test the hypothesis that the eelgrass (Zostera marina) leaf microbiome increases resistance to seagrass wasting disease. From field eelgrass with paired diseased and asymptomatic tissue,16S rRNAgene amplicon sequencing revealed that bacterial composition and richness varied markedly between diseased and asymptomatic tissue in one of the two years. This suggests that the influence of disease on eelgrass microbial communities may vary with environmental conditions. We next experimentally reduced the eelgrass microbiome with antibiotics and bleach, then inoculated plants withLabyrinthula zosterae, the causative agent of wasting disease. We detected significantly higher disease severity in eelgrass with a native microbiome than an experimentally reduced microbiome. Our results over multiple experiments do not support a protective role of the eelgrass microbiome againstL. zosterae. Further studies of these marine host–microbe–pathogen relationships may continue to show new relationships between plant microbiomes and diseases.
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This content will become publicly available on July 27, 2027
Microbiota assembly in Zostera marina during early host development across controlled growth experiments
ABSTRACT Seagrass restoration practices are evolving to leverage microbiome applications, similar to agricultural systems that have demonstrated how targeted microbial communities enhance crop resilience in challenging environments. While adult seagrass microbiome research has expanded significantly, research on the seed microbiome remains critically understudied. This gap is important given that seeds represent a large portion of restoration efforts. Advancing seed microbiome research requires standardized experimental systems for controlled plant–microbe interaction studies, which are currently lacking in seagrass research. Here, we tested fabricated ecosystem devices (EcoFAB 2.0) as a standardized system for growingZostera marina(eelgrass) seedlings, enabling a controlled study of aquatic plant–microbe interactions. Using these chambers, we addressed three key questions: (i) can we reliably grow eelgrass in a controlled laboratory setting, (ii) can we manipulate eelgrass microbiota assembly and its long-term trajectory, and (iii) can we detect shifts in the microbiota during plant development (host filtering)? Host morphology measurements and 16S rRNA gene amplicon sequencing were used to track microbiota assembly across three early developmental stages of the host. Because plants were grown in a sterile environment, surface sterilization of seeds (bleach and ethanol) removed epiphytes without disturbing the shared endophytic community, yet microbiota composition remained divergent at Stage 6 (143 differentially abundant ASVs), indicating that seed coat epiphytes make a lasting and distinct contribution to assembly trajectory. We also identified 26 stage-specific indicator ASVs across eelgrass development, suggesting stage-specific microbial associations during seedling establishment. This work demonstrates the potential for targeted manipulation of the microbiome in seagrass for restoration efforts.IMPORTANCEUsing the Fabricated Ecosystem 2.0 (EcoFAB 2.0), we were able to successfully control the microbial environment of eelgrass,Zostera marina, resulting in the reduction of epiphytes and maintaining low microbial diversity across plants without compromising the morphology and growth of seedlings. Our findings advance the marine plant model system,Z. marina, by identifying taxonomic indicators across life stages. This work lays the foundation for a targeted understanding and application of microbiomes for seagrass restoration, bridging the critical knowledge gap between agricultural seed microbiome success and marine restoration applications.
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- Award ID(s):
- 2311577
- PAR ID:
- 10706147
- Editor(s):
- Bittleston, Leonora S
- Publisher / Repository:
- ASM Journal
- Date Published:
- Journal Name:
- mSystems
- ISSN:
- 2379-5077
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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