title: Trapping of the quenched conformation associated with non-photochemical quenching of chlorophyll fluorescence at low temperature.
abstract: The kinetics of non-photochemical quenching (NPQ) of chlorophyll fluorescence was studied in pea leaves at different temperatures between 5 and 25 degrees C and during rapid jumps of the leaf temperature. At 5 degrees C, NPQ relaxed very slowly in the dark and was sustained for up to 30 min. This was independent of the temperature at which quenching was induced. Upon raising the temperature to 25 degrees C, the quenched state relaxed within 1 min, characteristic for qE, the energy-dependent component of NPQ. Measurements of the membrane permeability (delta A515) in dark-adapted and preilluminated leaves and NPQ in the presence of dithiothreitol strongly suggest that the effect of low temperature on NPQ was not because of limitation by the lumenal pH or the de-epoxidation state of the xanthophylls. These data are consistent with the notion that the transition from the quenched to the unquenched state and vice versa involves a structural reorganization in the photosynthetic apparatus. An eight-state reaction scheme for NPQ is proposed, extending the model of Horton and co-workers (FEBS Lett 579:4201-4206, 2005), and a hypothesis is put forward concerning the nature of conformational changes associated with qE.
authors.affiliation: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, 6726, Szeged, Hungary.
authors.forename: Petar H
authors.initials: PH
authors.lastname: Lambrev
authors.forename: Tsonko
authors.initials: T
authors.lastname: Tsonev
authors.forename: Violeta
authors.initials: V
authors.lastname: Velikova
authors.forename: Katya
authors.initials: K
authors.lastname: Georgieva
authors.forename: Maya D
authors.initials: MD
authors.lastname: Lambreva
authors.forename: Ivan
authors.initials: I
authors.lastname: Yordanov
authors.forename: László
authors.initials: L
authors.lastname: Kovács
authors.forename: Gyozo
authors.initials: G
authors.lastname: Garab
mesh_terms: D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D005453:Fluorescence; D007700:Kinetics; D018532:Pisum sativum / Q000187:drug effects / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D013696:Temperature; D024341:Xanthophylls / Q000378:metabolism; D065146:Zeaxanthins