2022 Fiscal Year Annual Research Report
The functional role of photosynthesis-related genes in non-photosynthetic symbionts of corals
| Project/Area Number |
21F21081
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| Allocation Type | Single-year Grants |
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| Research Institution | Okinawa Institute of Science and Technology Graduate University |
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| Host Researcher |
HUSNIK Filip 沖縄科学技術大学院大学, 進化・細胞・共生の生物学ユニット, 准教授 (30886130)
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| Foreign Research Fellow |
ALVES DOS SANTOS MARIA 沖縄科学技術大学院大学, 進化・細胞・共生の生物学ユニット, 外国人特別研究員
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| Project Period (FY) |
2021-09-28 – 2024-03-31
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| Keywords | evolution / symbiosis / corals |
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| Outline of Annual Research Achievements |
I sequenced and analyzed the symbionts of over 100 coral samples from Okinawa and 16 regions worldwide. Our results clarified their global distribution, as well as their localization in the coral tissues. For instance, Sanger sequencing of the 18S-rRNA gene region of corallicolids showed that coral species from Japan are associated with the same lineage, and this same corallicolid clade is also symbiotic with coral species from different Hawai’i and the Caribbean Sea. Additionally, our results with amplicon sequencing (16S, 18S, and ITS2) indicated global patterns of coral-symbiont diversity. The predominant bacteria phylum associated with coral samples worldwide was Proteobacteria, such as the mutualistic Endozoicomonas and the pathogenic Vibrios. As expected, the most abundant eukaryote associated with coral colonies was Dinoflagellate, especially zooxanthellae of Cladocopium, followed by Durisdinium. A few samples were also associated with lineages of Symbiodinium, mostly restricted to the Atlantic Ocean. Other common microeukaryotes were apicomplexans of corallicolids, chromerids, and Fungi. Furthermore, our results indicated that corallicolids were more abundant in samples from the Atlantic Ocean compared to the Indo-Pacific Ocean, including Okinawa.
Our metagenomic and genomic results confirmed the high diversity of coral microbes. Moreover, we reported a potentially undescribed bacteria species of the genus Spiroplasma, and its genes indicated that this might be a mutualistic symbiont.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The initial aims of the project (primary focus on corallicolids) were slightly changed during the project in order to avoid competition with several other research groups who we realized were working on similar goals. The project has resulted in a massive dataset on the population-level diversity of coral symbioses and evolution across the globe.
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| Strategy for Future Research Activity |
One large manuscript is currently in its final preparation stage (all figures ready and a preliminary text drafted) for publication with expected submission in 2024. Several additional manuscripts on evolution of coral symbiosis at global scale will take advantage of the large dataset generated by this project. The comprehensive nature of the data will also allow us to propose new questions and continue the research project with in-depth analyses and experiments (e.g., the role of certain bacteria such as the newly identified Spiroplasma). Future work, including single cell ‘omics’, will contribute to further clarifying the function of these symbionts.
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[Presentation] Global diversity of coral symbionts2022
Author(s)
Santos MEA, Reimer JD, Mizuyama M, Kise H, Boo WH, Iguchi A, Dudoi A, Toonen R, Kitahara MV, Husnik F
Organizer
3rd OIST-Tohoku University Joint Workshop “Biodiversity: From genes and species to ecosystem services and resilience”
