title: Diversity and oceanic distribution of prasinophytes clade VII, the dominant group of green algae in oceanic waters.
abstract: Prasinophytes clade VII is a group of pico/nano-planktonic green algae (division Chlorophyta) for which numerous ribosomal RNA (rRNA) sequences have been retrieved from the marine environment in the last 15 years. A large number of strains have also been isolated but have not yet received a formal taxonomic description. A phylogenetic analysis of available strains using both the nuclear 18S and plastidial 16S rRNA genes demonstrates that this group composes at least 10 different clades: A1-A7 and B1-B3. Analysis of sequences from the variable V9 region of the 18S rRNA gene collected during the Tara Oceans expedition and in the frame of the Ocean Sampling Day consortium reveal that clade VII is the dominant Chlorophyta group in oceanic waters, replacing Mamiellophyceae, which have this role in coastal waters. At some location, prasinophytes clade VII can even be the dominant photosynthetic eukaryote representing up to 80% of photosynthetic metabarcodes overall. B1 and A4 are the overall dominant clades and different clades seem to occupy distinct niches, for example, A6 is dominant in surface Mediterranean Sea waters, whereas A4 extend to high temperate latitudes. Our work demonstrates that prasinophytes clade VII constitute a highly diversified group, which is a key component of phytoplankton in open oceanic waters but has been neglected in the conceptualization of marine microbial diversity and carbon cycle.
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.
authors: Adriana
authors: A
authors: Lopes Dos Santos
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.
authors: Priscillia
authors: P
authors: Gourvil
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.
authors: Margot
authors: M
authors: Tragin
authors: National Institute for Environmental Studies, Tsukuba, Japan.
authors: Mary-Hélène
authors: MH
authors: Noël
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.|Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
authors: Johan
authors: J
authors: Decelle
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.
authors: Sarah
authors: S
authors: Romac
authors: Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.
authors: Daniel
authors: 0000-0002-0717-5685
authors: D
authors: Vaulot
mesh_terms: D000460:Chlorophyta / Q000145:classification / Q000235:genetics*; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D056890:Eukaryota / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D014644:Genetic Variation; D008522:Mediterranean Sea; D009792:Oceans and Seas; D010788:Photosynthesis; D010802:Phylogeny; D010839:Phytoplankton / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D012623:Seawater
chemical_list: D004275:DNA, Ribosomal