title: Photosystem II repair in marine diatoms with contrasting photophysiologies.
abstract: Skeletonema costatum and Phaeodactylum tricornutum are model marine diatoms with differing strategies for non-photochemical dissipation of excess excitation energy within photosystem II (PSII). We showed that S. costatum, with connectivity across the pigment bed serving PSII, and limited capacity for induction of sustained non-photochemical quenching (NPQ), maintained a large ratio of [PSII(Total)]/[PSII(Active)] to buffer against fluctuations in light intensity. In contrast, P. tricornutum, with a larger capacity to induce sustained NPQ, could maintain a lower [PSII(Total)]/[PSII(Active)]. Induction of NPQ was correlated with an active PSII repair cycle in both species, and inhibition of chloroplastic protein synthesis with lincomycin leads to run away over-excitation of remaining PSII(Active), particularly in S. costatum. We discuss these distinctions in relation to the differing capacities, induction and relaxation rates for NPQ, and as strain adaptations to the differential light regimes of their originating habitats. The present work further confirms the important role for the light-dependent fast regulation of photochemistry by NPQ interacting with PSII repair cycle capacity in the ecophysiology of both pennate and centric diatoms.
authors.affiliation: UMRi 7266 'LIENSs', Institut du Littoral et de l'Environnement (ILE), CNRS-University of La Rochelle, 2 rue Olympe de Gouges, 17000, La Rochelle Cedex, France. johann.lavaud@univ-lr.fr.
authors.forename: Johann
authors.initials: J
authors.lastname: Lavaud
authors.affiliation: Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada.|UMR 7144 'Adaptation et Diversité en Milieu Marin', 'Marine Phototrophic Prokaryotes' group, Centre National pour la Recherche Scientifique (CNRS), Station Biologique de Roscoff, Place George Teissier, 29680, Roscoff, France.|UMR 7144 'Adaptation et Diversité en Milieu Marin', 'Marine Phototrophic Prokaryotes' group, Université Pierre et Marie Curie (Paris 06), Station Biologique de Roscoff, Place George Teissier, 29680, Roscoff, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Six
authors.affiliation: Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Campbell
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D017377:Diatoms / Q000378:metabolism* / Q000528:radiation effects; D005453:Fluorescence; D007700:Kinetics; D008027:Light; D010777:Photochemistry; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D012623:Seawater
chemical_list: D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit; D002734:Chlorophyll
keywords: Diatoms; Ecophysiology; Non-photochemical fluorescence quenching; Photoprotection; Photosystem II repair; PsbA (D1) protein