title: The plastoquinone pool of Nannochloropsis oceanica is not completely reduced during bright light pulses.
abstract: The lipid-producing model alga Nannochloropsis oceanica has a distinct photosynthetic machinery. This organism possesses chlorophyll a as its only chlorophyll species, and has a high ratio of PSI to PSII. This high ratio of PSI to PSII may affect the redox state of the plastoquinone pool during exposure to light, and consequently may play a role in activating photoprotection mechanisms. We utilized pulse-amplitude modulated fluorometry to investigate the redox state of the plastoquinone pool during and after bright light pulses. Our data indicate that even very intense (5910 μmol photons s-1m-2 of blue light having a wavelength of 440 nm) light pulses of 0.8 second duration are not sufficient to completely reduce the plastoquinone pool in Nannochloropsis. In order to achieve extensive reduction of the plastoquinone pool by bright light pulses, anaerobic conditions or an inhibitor of the photosynthetic electron transport chain has to be utilized. The implication of this finding for the application of the widely used saturating pulse method in algae is discussed.
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Gunvor
authors.identifier: http://orcid.org/0000-0001-6960-9883
authors.initials: G
authors.lastname: Røkke
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Thor Bernt
authors.initials: TB
authors.lastname: Melø
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Martin Frank
authors.initials: MF
authors.lastname: Hohmann-Marriott
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D010971:Plastoquinone / Q000378:metabolism*; D058009:Stramenopiles / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D002734:Chlorophyll; D010971:Plastoquinone