Host-virus interactions in marine diatoms across environmental and ecophysiological gradients

Project Information

InterDiVE

Grant agreement ID: 101076118

DOI

10.3030/101076118

EC signature date 20 December 2022

Start date 1 May 2023

End date 30 April 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 868 196,00

EU contribution

€ 1 868 196,00

Coordinated by

BAR ILAN UNIVERSITY
Israel

Periodic Reporting for period 1 - InterDiVE (Host-virus interactions in marine diatoms across environmental and ecophysiological gradients)

Reporting period: 2023-05-01 to 2025-10-31

Summary of the context and overall objectives of the project

Diatoms are a ubiquitously distributed group of microalgae and key contributors to the global carbon cycle, regulating the drawdown of atmospheric carbon dioxide and its burial in the deep ocean. This global significance underscores the importance of elucidating the underlying factors that shape diatom population dynamics and ultimately determine diatom fate. Decades of research demonstrate, unequivocally, that marine viruses significantly influence microbial communities and are catalysts of biogeochemical transformation in the water column. Yet we know very little about how viruses impact diatom populations. When and where does virus infection of diatom populations occur in the ocean? What are the factors that contribute to the ability of diatom-infecting viruses to propagate within and terminate a population? And, how does viral infection manifest within the taxonomic and functional diversity of a natural diatom assemblage? Considering recent advances in our ability to detect and study diatom host-virus dynamics, we are now poised to address these questions.

Understanding how microscale, microbial dynamics in the ocean respond to fluctuating environmental conditions is essential for an accurate assessment of primary production and biogeochemical cycles in our changing oceans. In this proposal, we aim to elucidate how environmental and ecophysiological gradients shape diatom host-virus interactions. Using a combination of laboratory and field-based approaches, we will explore these dynamics on multiple scales, encompassing both host-virus population dynamics and viral infection at single cell resolution. We will determine how diverse environmental stressors influence virus life history traits and virus-mediated mortality in diatoms and resolve the ecophysiological frameworks that underscore and drive divergent diatom host-virus interactions. Furthermore, we aim to capture and contextualize host-virus interactions across spatial and temporal gradients within diverse, natural diatom assemblages in the ocean. We anticipate that this research will advance a new and exciting frontier in aquatic virology, unravelling the factors that contribute to the ecology of a distinct and understudied group of marine viruses. Altogether, proposed research will provide a comprehensive view of host-virus interactions in diatoms that spans from the single cell to the community, offering both environmental context and molecular insight into the factors that regulate diatom fate.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In order to capture diatom host-virus interactions in a natural diatom assemblage, and as part of the ERC project, we have conducted several targeted field sampling campaigns tracking diatom community dynamics within the spring bloom in the Gulf of Aqaba, Northern Red Sea and additionally, had the opportunity to conduct parallel sampling in the seasonal upwelling plumes in the northeast Pacific. Using a combination of quantitative microeukaryote metatranscriptomics and targeted virus quantification within the peak of a diatom bloom event in the Red Sea, we were able to track dynamic transitions in diatom taxa and corresponding transitions in several distinct RNA viruses, suggesting active virus infection and possibly virus-mediated diatom succession within a single bloom event. To explore these dynamics more broadly and elucidate how viruses interface with diatom communities over environmental gradients, we recently completed a two month-long sampling of the spring bloom in the Red Sea, paired with a series of short-term microcosm, incubation experiments. In parallel, using a combination of physiological, molecular, biogeochemical and 'omics-based techniques, we are working with model diatom and virus isolates in a series of controlled, laboratory-based experiments to better understand how diverse environmental conditions shape host-virus dynamics in diatoms. Since the beginning of the InterDIVE project we found: a) rapid RNA virus population turnover within the aforementioned diatom bloom in the Red Sea, b) unique transcriptomic reprogramming of diatoms infected by RNA viruses, c) a subset of putative biomarker genes and antiviral genes related to RNA virus infection in diatoms and d) a shift in virus life history traits and transient resistance to virus-mediated infection across gradients of macronutrient availability.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Based on what we have accomplished during the project thus far, we anticipate that our research will resolve a continuum of diatom host-virus interactions and ultimately determine how environmental and ecophysiological gradients regulate virus infection dynamics in diatoms. Most of our field sampling is complete, much of the proposed experimental pipelines for sample processing and analysis are up and running and our preliminary data suggest that we are on the right track to meet the long-term goals of the project. Proposed research will not only substantially expand our knowledge of when, where and how viruses might regulate diatom fate, but will also open new directions of research in marine virus and diatom molecular ecology and ecophysiology, helping to further resolve the microscale, microbial interactions that underpin large scale processes in the global ocean.

InterDIVE Graphic