title: System responses to equal doses of photosynthetically usable radiation of blue, green, and red light in the marine diatom Phaeodactylum tricornutum.
abstract: Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions.
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Kristin Collier
authors.initials: KC
authors.lastname: Valle
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Marianne
authors.initials: M
authors.lastname: Nymark
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Inga
authors.initials: I
authors.lastname: Aamot
authors.affiliation: Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Hancke
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Per
authors.initials: P
authors.lastname: Winge
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Kjersti
authors.initials: K
authors.lastname: Andresen
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Johnsen
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Tore
authors.initials: T
authors.lastname: Brembu
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Atle M
authors.initials: AM
authors.lastname: Bones
mesh_terms: D002338:Carotenoids / Q000096:biosynthesis; D002734:Chlorophyll / Q000096:biosynthesis / Q000235:genetics; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism; D017377:Diatoms / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D010788:Photosynthesis / Q000235:genetics*; D045332:Photosystem II Protein Complex / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000528:radiation effects; D059467:Transcriptome
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D002338:Carotenoids; D000077194:Chlorophyll A