Alan Denis Fernández‐Valero

Institut Català de Ciències del Clima

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Albert Reñé

Institut Català de Ciències del Clima

Esther Garcés

Institut Català de Ciències del Clima

Nagore Sampedro

Institut de Ciències del Mar

Natàlia Timoneda

Institut Català de Ciències del Clima

Jordina Gordi

Institut Català de Ciències del Clima

Elisabet Alacid

Centre d'Estudis Avançats de Blanes

R. Gallisai

Institut de Ciències del Mar

Eva Flo Arcas

Institut Català de Ciències del Clima

Sergey A. Karpov

Zoological Institute

Massimo C. Pernice

Institut de Ciències del Mar

Cooperative Institutions

Institut Català de Ciències del Clima

Institut de Ciències del Mar

Consejo Superior de Investigaciones Científicas

Centre National de la Recherche Scientifique

Université Paris-Saclay

AgroParisTech

Écologie, Systématique et Évolution

University of Exeter

Government of Catalonia

Centro Mediterráneo de Investigaciones Marinas y Ambientale

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Newly identified diversity of Dinomycetaceae (Rhizophydiales, Chytridiomycota), a family of fungal parasites of marine dinoflagellates

European Journal of Protistology (2024)

Alan Denis Fernández‐Valero Sergey A. Karpov Nagore Sampedro Jordina Gordi Natàlia Timoneda

We identified two new parasite species of Chytridiomycota isolated during blooms of the dinoflagellate Alexandrium minutum in the coastal Mediterranean Sea. Light and electron microscopy together with molecular characterization of the nuclear 18S, ITS, and 28S rDNA regions led to their identification as two new species, Dinomyces gilberthii and Paradinomyces evelyniae, both belonging to the family Dinomycetaceae, order Rhizophydiales. Dinomyces gilberthii differs from the previously described D. arenysensis by the presence of discharge papillae and the development of a drop-shaped sporangium. Paradinomyces evelyniae differs from the previously described P. triforaminorum by the prominent lipid globule present in early sporangia and the pointed end producing a rhizoid. The two chytrids differed in their geographical distribution. Dinomyces gilberthii was detected in several Mediterranean habitats, including harbours and beaches, and was particularly prevalent during summer dinoflagellate blooms. This widespread occurrence in coastal ecosystems suggested a high level of adaptability in this environment. Paradinomyces evelyniae had a more restricted distribution in the coastal-marine environment, occurring in harbour sediments and only occasionally in the water column during winter and early spring. Paradinomyces evelyniae has previously been detected in the Baltic Sea, suggesting that its distribution encompasses contrasting coastal environments, although its presence is rare.

Chytridiomycota

Dinoflagellate

Oomycete

10.1016/j.ejop.2024.126053

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Citations (1)

The succession of epiphytic microalgae conditions fungal community composition: how chytrids respond to blooms of dinoflagellates

ISME Communications (2023)

Alan Denis Fernández‐Valero Albert Reñé Natàlia Timoneda Núria Pou-Solà Jordina Gordi

This study aims to investigate the temporal dynamics of the epiphytic protist community on macroalgae, during the summer months, with a specific focus on fungi, and the interactions between zoosporic chytrid parasites and the proliferation of the dinoflagellates. We employed a combination of environmental sequencing techniques, incubation of natural samples, isolation of target organisms and laboratory experiments. Metabarcoding sequencing revealed changes in the dominant members of the epiphytic fungal community. Initially, fungi comprised < 1% of the protist community, mostly accounted for by Basidiomycota and Ascomycota, but with the emergence of Chytridiomycota during the mature phase of the biofilm, the fungal contribution increased to almost 30%. Chytridiomycota became dominant in parallel with an increase in the relative abundance of dinoflagellates in the community. Microscopy observations showed a general presence of chytrids following the peak proliferation of the dinoflagellate Ostreopsis sp., with the parasite, D. arenysensis as the dominant chytrid. The maximum infection prevalence was 2% indicating host-parasite coexistence. To further understand the in-situ prevalence of chytrids, we characterised the dynamics of the host abundance and prevalence of chytrids through co-culture. These laboratory experiments revealed intraspecific variability of D. arenysensis in its interaction with Ostreopsis, exhibiting a range from stable coexistence to the near-extinction of the host population. Moreover, while chytrids preferentially parasitized dinoflagellate cells, one of the strains examined displayed the ability to utilize pollen as a resource to maintain its viability, thus illustrating a facultative parasitic lifestyle. Our findings not only enrich our understanding of the diversity, ecology, and progression of epiphytic microalgal and fungal communities on Mediterranean coastal macroalgae, but they also shed light on the presence of zoosporic parasites in less-explored benthic habitats.

Chytridiomycota

Dinoflagellate

Epiphyte

Protist

10.1038/s43705-023-00304-x

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New Perkinsea Parasitoids of Dinoflagellates Distantly Related to Parviluciferaceae Members

Frontiers in Microbiology (2021)

Albert Reñé Elisabet Alacid R. Gallisai Aurélie Chambouvet Alan Denis Fernández‐Valero

Perkinsea is a phylogenetic group of protists that includes parasites of distantly related hosts. However, its diversity is still mainly composed of environmental sequences, mostly obtained from freshwater environments. Efforts to isolate and culture parasitoids of dinoflagellates have led to the description of several phylogenetically closely related species constituting the Parviluciferaceae family. In this study, two new parasitoid species infecting dinoflagellates during recurrent coastal blooms are reported. Using the ribosomal RNA (rRNA) gene phylogenies, we show that both cluster within Perkinsea, one of them at the base of Parviluciferaceae and the other in a distinct branch unrelated to other described species. The establishment of host-parasite lab cultures of the latter allowed its morphological characterization, resulting in the formal description of Maranthos nigrum gen. nov., sp. nov. The life-cycle development of the two parasitoids is generally the same as that of other members of the Parviluciferaceae family but they differ in the features of the trophont and sporont stages, including the arrangement of zoospores during the mature sporangium stage and the lack of specialized structures that release the zoospores into the environment. Laboratory cross-infection experiments showed that the parasitoid host range is restricted to dinoflagellates, although it extends across several different genera. The maximum prevalence reached in the tested host populations was lower than in other Parviluciferaceae members. The findings from this study suggest that Perkinsea representatives infecting dinoflagellates are more widespread than previously thought.

Zoospore

10.3389/fmicb.2021.701196

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Citations (11)

Host preferences of coexisting Perkinsea parasitoids during coastal dinoflagellate blooms

bioRxiv (Cold Spring Harbor Laboratory) (2021)

Albert Reñé Natàlia Timoneda Nagore Sampedro Elisabet Alacid R. Gallisai

ABSTRACT Parasites in aquatic systems are highly diverse and ubiquitous. In marine environments, parasite-host interactions contribute substantially to shaping microbial communities, but their nature and complexity remain poorly understood. In this study, we examined the relationship between Perkinsea parasitoids and bloom-forming dinoflagellate species. Our aim was to determine whether parasite-host species interactions are specific and whether the diversity and distribution of parasitoids are shaped by their dinoflagellate hosts. Several locations along the Catalan coast (NW Mediterranean Sea) were sampled during the blooms of five dinoflagellate species and the diversity of Perkinsea was determined by combining cultivation-based methods with metabarcoding of the V4 region of 18S rDNA. Most known species of Parviluciferaceae, and others not yet described, were detected, some of them coexisting in the same coastal location, and with a wide distribution. The specific parasite-host interactions determined for each of the studied blooms demonstrated the host preferences exhibited by parasitoids in nature. The dominance of a species within the parasitoid community is driven by the presence and abundances of its preferred host(s).The absence of parasitoid species, often associated with a low abundance of their preferred hosts, suggested that high infection rates are reached only under conditions that favour parasitoid propagation, especially dinoflagellate blooms.

Dinoflagellate

Dominance (genetics)

10.1101/2021.02.17.431570

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Citations (0)

Dinoflagellate hosts determine the community structure of marine Chytridiomycota: Demonstration of their prominent interactions

Environmental Microbiology (2022)

Alan Denis Fernández‐Valero Albert Reñé Natàlia Timoneda Nagore Sampedro Esther Garcés

Abstract The interactions of parasitic fungi with their phytoplankton hosts in the marine environment are mostly unknown. In this study, we evaluated the diversity of Chytridiomycota in phytoplankton communities dominated by dinoflagellates at several coastal locations in the NW Mediterranean Sea and demonstrated the most prominent interactions of these parasites with their hosts. The protist community in seawater differed from that in sediment, with the latter characterized by a greater heterogeneity of putative hosts, such as dinoflagellates and diatoms, as well as a chytrid community more diverse in its composition and with a higher relative abundance. Chytrids accounted for 77 amplicon sequence variants, of which 70 were found exclusively among different blooming host species. The relative abundance of chytrids was highest in samples dominated by the dinoflagellate genera Ostreopsis and Alexandrium , clearly indicating the presence of specific chytrid communities. The establishment of parasitoid‐host co‐cultures of chytrids and dinoflagellates allowed the morphological identification and molecular characterization of three species of Chytridiomycota, including Dinomyces arenysensis , as one of the most abundant environmental sequences, and the discovery of two other species not yet described.

Chytridiomycota

Dinoflagellate

Protist

Gymnodinium

10.1111/1462-2920.16182

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Citations (12)

Newly Identified Diversity of Dinomycetaceae (Rhizophydiales, Chytridiomycota), a Family of Fungal Parasites of Marine Dinoflagellates

Alan Denis Fernández‐Valero Sergey A. Karpov Nagore Sampedro Jordina Gordi Natàlia Timoneda

We identified two new parasite species of Chytridiomycota isolated during blooms of the dinoflagellate Alexandrium minutum in the coastal Mediterranean Sea. Light and electron microscopy together with molecular characterization of the 18S, ITS, and 28S rDNA regions led to their identification as two new species, Dinomyces gilberthii and Paradinomyces evelyniae, both belonging to the family Dinomycetaceae, Order Rhizophydiales. D. gilberthii differs from the previously described D. arenysensis by the presence of discharge papillae and the development of a drop-shaped sporangium. P. evelyniae differs from the previously described P. triforaminorum by the prominent lipid globule present in early sporangia and the pointed end producing a rhizoid. The two chytrids differed in their geographical distribution. D. gilberthii was detected in several Mediterranean habitats, including harbours and beaches, and was particularly prevalent during summer dinoflagellate blooms. This widespread occurrence in coastal ecosystems suggested a high level of adaptability in this environment. P. evelyniae had a more restricted distribution in the coastal-marine environment, occurring in harbour sediments and only occasionally in the water column during winter and early spring. P. evelyniae has previously been detected in the Baltic Sea and this suggests that its distribution encompasses contrasting coastal environments, although its presence is rare.

Chytridiomycota

Fungal Diversity

10.2139/ssrn.4601774

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Citations (0)

Host preferences of coexisting Perkinsea parasitoids during coastal dinoflagellate blooms

Molecular Ecology (2021)

Albert Reñé Natàlia Timoneda Nagore Sampedro Elisabet Alacid R. Gallisai

Parasites in aquatic systems are highly diverse and ubiquitous. In marine environments, parasite-host interactions contribute substantially to shaping microbial communities, but their nature and complexity remain poorly understood. In this study, we examined the relationship between Perkinsea parasitoids and bloom-forming dinoflagellate species. Our aim was to determine whether parasite-host species interactions are specific and whether the diversity and distribution of parasitoids are shaped by their dinoflagellate hosts. Several locations along the Catalan coast (NW Mediterranean Sea) were sampled during the blooms of five dinoflagellate species and the diversity of Perkinsea was determined by combining cultivation-based methods with metabarcoding of the V4 region of 18S rDNA. Most known species of Parviluciferaceae, and others not yet described, were detected, some of them coexisting in the same coastal location, and with a wide distribution. The specific parasite-host interactions determined for each of the studied blooms demonstrated the host preferences exhibited by parasitoids in nature. The dominance of a species within the parasitoid community is driven by the presence and abundances of its preferred host(s). The absence of parasitoid species, often associated with a low abundance of their preferred hosts, suggested that high infection rates are reached only under conditions that favour parasitoid propagation, especially dinoflagellate blooms.

Dinoflagellate

10.1111/mec.15895

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Citations (15)