title: Plants impaired in state transitions can to a large degree compensate for their defect.
abstract: Arabidopsis thaliana plants lacking the PSI-H or PSI-L subunit of photosystem I have been shown to be severely affected in their ability to perform state transitions, but no visual phenotype was observed when these plants were grown under different light quantities and qualities. However, the chloroplasts in the PSI-H- and PSI-L-less plants contained fewer and more extended grana stacks. The plants lacking PSI-H or PSI-L were characterised with respect to their photosynthetic performance. Wild-type plants adjusted the non-photochemical fluorescence quenching to maintain constant levels of PSII quantum yield and reduction of the plastoquinone pool. In contrast, the plants deficient in state transitions had a more reduced plastoquinone pool and consequently, a less efficient PSII-photochemistry under growth-light conditions and in state 2. The maximal photosynthetic capacity and the quantum efficiency of oxygen evolution were diminished by 8-14% in the PSI-H-less plants. Under growth-light conditions, the stroma was similarly reduced in the PSI-H-less plants and the rate of cyclic electron transport was unchanged. Pigment analysis showed that the xanthophyll cycle was not upregulated in order to compensate for the lack of state transitions. In general, the plants lacking PSI-H and PSI-L showed a decreased ability to optimise photosynthesis according to the light conditions.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: Christina
authors.initials: C
authors.lastname: Lunde
authors.forename: Poul Erik
authors.initials: PE
authors.lastname: Jensen
authors.forename: Lisa
authors.initials: L
authors.lastname: Rosgaard
authors.forename: Anna
authors.initials: A
authors.lastname: Haldrup
authors.forename: Margaret Joan
authors.initials: MJ
authors.lastname: Gilpin
authors.forename: Henrik Vibe
authors.initials: HV
authors.lastname: Scheller
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D002736:Chloroplasts / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D004579:Electron Transport / Q000502:physiology / Q000528:radiation effects; D005453:Fluorescence; D008027:Light; D008854:Microscopy, Electron; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D045331:Photosystem I Protein Complex; D010860:Pigments, Biological / Q000378:metabolism; D010971:Plastoquinone / Q000378:metabolism; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010860:Pigments, Biological; D024341:Xanthophylls; D010971:Plastoquinone; D010100:Oxygen