The Zostera muelleri seagrass microbiome

Publication Type:
Issue Date:
Full metadata record
As many other terrestrial macroorganisms, marine benthic animals and plants establish tight relationships with a collection of microbes widely known as the microbiome. These interactions are maintained in a delicate ecological equilibrium that affects hostsโ€™ metabolism and health, and ultimately the biogeochemical processes and ecosystems that rely on them. Seagrasses are aquatic angiosperms that play critical ecological roles and provide very valuable ecosystem services. These plants are now considered holobiont models in the ocean, given the increasing evidence of the relevance of their associations with a wide range of microorganisms. However, seagrass microbiome research is still on its infancy, and our understanding of their dynamics at different spatial scales and the influence of the external environment is still very limited, particularly for the seagrass species ๐˜ก๐˜ฐ๐˜ด๐˜ต๐˜ฆ๐˜ณ๐˜ข ๐˜ฎ๐˜ถ๐˜ฆ๐˜ญ๐˜ญ๐˜ฆ๐˜ณ๐˜ช. Despite the undeniable importance of microscale heterogeneity for marine microbial ecology, most investigations on the seagrass microbiome have identified microbial associates within the phyllosphere and rhizosphere, rather than at smaller microenvironmental scales that are likely most relevant to the organisms of interest. The aims of this thesis were to identify the microbial communities that live in association with ๐˜ก. ๐˜ฎ๐˜ถ๐˜ฆ๐˜ญ๐˜ญ๐˜ฆ๐˜ณ๐˜ช and to investigate how changes in the environment or the host influence the seagrass microbiome. Microbial community structure, diversity and levels of conservation, and co-occurrence patterns of bacterial, microalgal and fungal members were explored at the regional and plant scales in a variety of marine locations characterised by different environmental conditions. The dynamics of the ๐˜ก. ๐˜ฎ๐˜ถ๐˜ฆ๐˜ญ๐˜ญ๐˜ฆ๐˜ณ๐˜ช microbiome were also investigated within the contexts of disease and environmentally-driven physiological changes of the host, to assess how and to what extent intrinsic features of the plant influence its associated microbiota. Throughout the thesis, it was consistently demonstrated that the seagrass microbiome is highly dynamic and influenced by environmental and host-associated factors, and as a consequence significantly different microbial communities associate with disparate microenvironments or tissue types within a single plant. I also showed that certain core members within these communities are conserved at larger spatial scales, although this biogeographical signal can be lost in a diseased holobiont. Moreover, I demonstrated that substantial microbial changes in the phyllosphere, with potential detrimental effects, are concomitant with physiological responses of the host against climate stressors.
Please use this identifier to cite or link to this item: