title: In situ associations between marine photosynthetic picoeukaryotes and potential parasites - a role for fungi?
abstract: Photosynthetic picoeukaryotes (PPEs) are important components of the marine picophytoplankton community playing a critical role in CO2 fixation but also as bacterivores, particularly in the oligotrophic gyres. Despite an increased interest in these organisms and an improved understanding of the genetic diversity of this group, we still know little of the environmental factors controlling the abundance of these organisms. Here, we investigated the quantitative importance of eukaryotic parasites in the free-living fraction as well as in associations with PPEs along a transect in the South Atlantic. Using tyramide signal amplification-fluorescence in situ hybridization (TSA-FISH), we provide quantitative evidence of the occurrence of free-living fungi in open ocean marine systems, while the Perkinsozoa and Syndiniales parasites were not abundant in these waters. Using flow cytometric cell sorting of different PPE populations followed by a dual-labelled TSA-FISH approach, we also demonstrate fungal associations, potentially parasitic, occurring with both pico-Prymnesiophyceae and pico-Chrysophyceae. These data highlight the necessity for further work investigating the specific role of marine fungi as parasites of phytoplankton to improve understanding of carbon flow in marine ecosystems.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.|Université Clermont Auvergne, Université Blaise Pascal, Laboratoire 'Microorganismes : Génome et Environnement', BP 10448, Clermont-Ferrand, F-63000, France.|CNRS, UMR 6023, LMGE, Aubière, F-63171, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Lepère
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, NSW, 2109, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Ostrowski
authors.affiliation: National Oceanography Centre, Hampshire, SO14 3ZH, UK.
authors.forename: Manuela
authors.initials: M
authors.lastname: Hartmann
authors.affiliation: National Oceanography Centre, Hampshire, SO14 3ZH, UK.
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Zubkov
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Scanlan
mesh_terms: D056893:Alveolata / Q000235:genetics / Q000302:isolation & purification*; D001267:Atlantic Ocean; D044822:Biodiversity; D005434:Flow Cytometry; D005658:Fungi / Q000235:genetics / Q000302:isolation & purification*; D006790:Host-Parasite Interactions; D017404:In Situ Hybridization, Fluorescence; D010839:Phytoplankton / Q000382:microbiology* / Q000469:parasitology*