Meet the Winners of the 2022 Best Article Award From FEMS Microbiology Reviews
Anna Roik, Miriam Reverter and Claudia Pogoreutz wrote the excellent review article “A roadmap to understanding diversity and function of coral reef-associated fungi” for our journal FEMS Microbiology Reviews. The Editors-in-Chief of FEMS Microbiology Reviews chose this as the best article from 2022 due to its comprehensive overview of the current knowledge on coral reef-associated fungi and its valuable insight into future research directions.
We interviewed all the authors to find out more about the inspiration behind this paper:
Could you provide a brief, simple overview of the topic your paper covers?
Coral reefs are considered the ‘rainforests of the sea’, owing to their high biodiversity and productivity that is unexpected in the nutrient-poor, tropical oceans, where they fringe coastlines. The ecological basis for this seemingly paradoxical observation is owed to an intimate symbiosis of the reef-building corals with intracellular dinoflagellate algae. These algae provide nutrients in the form of photosynthetic products to the coral, and thereby support much of the coral’s carbon demand and as such driving reef formation. Overall, this microbial symbiosis forms the functional basis of the ecological success of coral reefs over millions of years. Apart from these symbiotic algae, corals are further associated with other microorganisms.
We are just starting to get insights into the dynamics and potential functions of coral-associated bacterial communities suggesting their potential role in the health of the coral host, however we still know very little about other microbes, such as fungi. While there is important seminal work on coral-associated fungi available, our understanding of these interactions is still marginal compared to coral-algae symbiosis or coral-associated bacteria. These studies suggest roles as bioeroders, but also the presence of pathogenic or opportunistic fungi in corals. Considering the important roles of fungi as ecological driving forces on land, we suspect that coral- and reef-associated fungi may engage in a diversity of functions and may even form mutualistic interactions, contributing to nutrient cycling and provisioning, and the structuring of the overall coral-associated microbial communities through chemical cross-talk. In our paper, we provide a detailed overview over such potential functions of fungi in corals and on coral reefs.
What kinds of fungi live in coral reefs and are they symbiotic with any of the other organisms?
Sequencing data reveal that Ascomycota and Basidiomycota are very abundant on coral reefs. Members of these groups are very well known, since they have an appreciable diversity of terrestrial representatives including mushroom-forming fungi that are popular delicacies, but also plant symbionts such as mycorrhiza, and human and crop pathogens. Another common group of fungi reported from corals and sea anemones are the Chytridiomycota, a group of unicellular fungi that in other ecosystems encompasses some well-studied pathogens of amphibians and parasites of freshwater algae. Also notable are members of Penicillium – perhaps best known for the first discovery of antibiotics and their frequent use in cheese production and Aspergillus, which comprises fungi known to us humans for causing respiratory illness. Interestingly, the latter was found to be associated with a disease-like state in the emblematic sea fans (a group of soft coral) off the Eastern Pacific coast. Originally, this ‘sea fan aspergillosis’ has been described as a disease, but has recently been suggested to be a case of opportunistic fungi overwhelming their hosts’ immune defense. It will be exciting to investigate whether Aspergillus (or any other marine fungi, for that matter) may also engage in mutualistic symbiotic interactions with their coral hosts, their associated algae, or other organisms on the reef.
While the research focus has been on antagonistic relationships with marine fungi, there is fairly limited information on symbiotic relationships. However, there are examples of beneficial interactions which inspire the quest for marine fungal symbioses. As such, we know about the existence of natural fungi-bacteria associations in sediments or the presence of mycorrhiza-like fungi in the roots of Mediterranean seagrasses. Last but not least, exciting insights from synthetic laboratory co-cultures between a freshwater alga and a terrestrial fungus engaging in a mutualistic exchange suggest a very high potential for new, to date overlooked, fungal symbioses in the marine realm to be discovered.
What encouraged you to perform research in this area of microbiology?
In terrestrial environments, fungi are known to be true ecological driving forces. While aquatic – especially marine – environments are obviously very different from land, we must assume a plethora of associations with different organisms and functional niches that fungi could occupy in the ocean, especially on tropical coral reefs, the ‘Rainforests of the Sea’. While coral reef microbiology – in particular mycology – is still in its infancy, we believe there is much to be discovered and that an integrated understanding of reef-associated microbes, including that of fungi, will not only be of interest for bioprospecting efforts, but also be important for the development of meaningful management actions and disease monitoring and management.
What do you see as the next steps in this area of research?
Moving forward, we propose a two-pronged effort. First, it will be important to get a better understanding on the diversity and community dynamics of reef-associated fungi. This would require continued efforts in the development and streamlining of high-throughput sequencing applications for marine fungi. Second, it will be of interest to obtain a functional understanding of these fungi and their interactions with other organisms and their hosts on the reef through increased culture-dependent and -independent efforts. New technologies will help us to uncover how fungi contribute to coral reef health and functioning, and whether they can be instrumentalized to help maintain these ecosystems for future generations.
Read the 2022 award winning paper: A roadmap to understanding diversity and function of coral reef-associated fungi