title: PROTON GRADIENT REGULATION5 is essential for proper acclimation of Arabidopsis photosystem I to naturally and artificially fluctuating light conditions.
abstract: In nature, plants are challenged by constantly changing light conditions. To reveal the molecular mechanisms behind acclimation to sometimes drastic and frequent changes in light intensity, we grew Arabidopsis thaliana under fluctuating light conditions, in which the low light periods were repeatedly interrupted with high light peaks. Such conditions had only marginal effect on photosystem II but induced damage to photosystem I (PSI), the damage being most severe during the early developmental stages. We showed that PROTON GRADIENT REGULATION5 (PGR5)-dependent regulation of electron transfer and proton motive force is crucial for protection of PSI against photodamage, which occurred particularly during the high light phases of fluctuating light cycles. Contrary to PGR5, the NAD(P)H dehydrogenase complex, which mediates cyclic electron flow around PSI, did not contribute to acclimation of the photosynthetic apparatus, particularly PSI, to rapidly changing light intensities. Likewise, the Arabidopsis pgr5 mutant exhibited a significantly higher mortality rate compared with the wild type under outdoor field conditions. This shows not only that regulation of PSI under natural growth conditions is crucial but also the importance of PGR5 in PSI protection.
authors: Department of Biochemistry and Food Chemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland.
authors: Marjaana
authors: M
authors: Suorsa
authors: Sari
authors: S
authors: Järvi
authors: Michele
authors: M
authors: Grieco
authors: Markus
authors: M
authors: Nurmi
authors: Malgorzata
authors: M
authors: Pietrzykowska
authors: Marjaana
authors: M
authors: Rantala
authors: Saijaliisa
authors: S
authors: Kangasjärvi
authors: Virpi
authors: V
authors: Paakkarinen
authors: Mikko
authors: M
authors: Tikkanen
authors: Stefan
authors: S
authors: Jansson
authors: Eva-Mari
authors: EM
authors: Aro
mesh_terms: D000064:Acclimatization / Q000502:physiology* / Q000528:radiation effects; D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019069:Cell Respiration / Q000528:radiation effects; D004579:Electron Transport / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D008958:Models, Molecular; D009154:Mutation; D010084:Oxidation-Reduction / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects; D010641:Phenotype; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000528:radiation effects*; D045332:Photosystem II Protein Complex / Q000528:radiation effects; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D018892:Proton-Motive Force / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000502:physiology / Q000528:radiation effects
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; C465062:PGR5 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species