Chytrid infecting the bloom-forming marine diatom Skeletonema sp.: Morphology, phylogeny and distribution of a novel species within the Rhizophydiales

• Published in: Fungal biology Vol. 123; no. 6; pp. 471 - 480
• Main Authors: Garvetto, Andrea, Badis, Yacine, Perrineau, Marie-Mathilde, Rad-Menéndez, Cecilia, Bresnan, Eileen, Gachon, Claire M.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.06.2019
• Subjects: Marine fungi; Marine microbial diversity; NGS; Plankton parasites; Single-cell analysis; Plankton parasites; Marine fungi; Marine microbial diversity; NGS; Single-cell analysis
• ISSN: 1878-6146; 1878-6162
• DOI: 10.1016/j.funbio.2019.04.004

Chytrids have long been recognised as important parasites of microalgae in freshwater systems, able to shape the dynamics of blooms, the gene pool of their host and phytoplankton succession. In the sea however, where the presence of these organisms is erratic and ephemeral, studies concerning chytrids are sparse and confined to metabarcoding surveys or microscopy observations. Despite the scarcity of data, chytrid epidemics are supposed to play an important role in marine biogeochemical cycles, being one of the drivers of phytoplankton dynamics. Here we combine microscopy observations and in silico mining of a single-cell whole genome to molecularly and morphologically characterise a novel chytrid parasite of the dominant diatom genus Skeletonema. Morphological observations highlight features of the thallus and ascertain the parasitic nature of the interaction whilst the genetic markers obtained allows for a phylogenetic reconstruction, placing the new species in the order Rhizophydiales. Thanks to the molecular data obtained we are also able to provide a first investigation of the global distribution of this organism by screening the Ocean Sampling Day (OSD) dataset, highlighting a northern transatlantic dissemination. •We report a novel chytrid infecting the bloom-forming marine diatom Skeletonema sp.•Specimens are characterised via microscopy and SC whole genome amplification.•A SAG is mined to reconstruct the phylogeny of this novel Rhizophydiales.•Screening of metabarcoding databases highlights two distinct Atlantic populations.