title: Light-harvesting mutants show differential gene expression upon shift to high light as a consequence of photosynthetic redox and reactive oxygen species metabolism.
abstract: The amount of light energy that is harvested and directed to the photosynthetic machinery is regulated in order to control the production of reactive oxygen species (ROS) in leaf tissues. ROS have important roles as signalling factors that instigate and mediate a range of cellular responses, suggesting that the mechanisms regulating light-harvesting and photosynthetic energy transduction also affect cell signalling. In this study, we exposed wild-type (WT) Arabidopsis and mutants impaired in the regulation of photosynthetic light-harvesting (stn7, tap38 and npq4) to transient high light (HL) stress in order to study the role of these mechanisms for up- and downregulation of gene expression under HL stress. The mutants, all of which have disturbed regulation of excitation energy transfer and distribution, responded to transient HL treatment with surprising similarity to the WT in terms of general 'abiotic stress-regulated' genes associated with hydrogen peroxide and 12-oxo-phytodienoic acid signalling. However, we identified distinct expression profiles in each genotype with respect to induction of singlet oxygen and jasmonic acid-dependent responses. The results of this study suggest that the control of excitation energy transfer interacts with hormonal regulation. Furthermore, the photosynthetic pigment-protein complexes appear to operate as receptors that sense the energetic balance between the photosynthetic light reactions and downstream metabolism.
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, , 20014 Turku, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Tikkanen
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Gollan
authors.forename: Nageswara Rao
authors.initials: NR
authors.lastname: Mekala
authors.forename: Janne
authors.initials: J
authors.lastname: Isojärvi
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics; D019295:Computational Biology; D003517:Cyclopentanes / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D055537:Light Signal Transduction / Q000502:physiology*; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism*; D046228:Microarray Analysis; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D054883:Oxylipins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000235:genetics; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D026082:Singlet Oxygen / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D045342:Light-Harvesting Protein Complexes; C489731:NPQ4 protein, Arabidopsis; D054883:Oxylipins; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; C011006:jasmonic acid; D017346:Protein Serine-Threonine Kinases; C497212:STN7 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; C550563:TAP38 protein, Arabidopsis
keywords: light-harvesting; phosphorylation; reactive oxygen species; retrograde signalling; thermal dissipation