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|Title:||Photoadaptation in the green alga Spongiochloris sp. A three-fluorometer study||Authors:||Koblizek, M
|Issue Date:||1999||Publisher:||INST EXPERIMENTAL BOTANY, ACAD SCI CZECH REPUBLIC||Source:||PHOTOSYNTHETICA, 37(2). p. 307-323||Abstract:||The dark-adapted cells of the green alga Spongiochloris sp. were exposed to "white light" of 1000 mu mol(photon) m(-2) s(-1) for 2 h and then dark adapted for 1.5 h. Changes of photochemical activities during photoadaptation were followed by measurement of chlorophyll (Chl) fluorescence kinetics, 77 K emission spectra, photosynthetic oxygen evolution, and pigment composition. We observed a build-up of slowly-relaxing non-photochemical quenching which led to a decrease of the F-v/F-m parameter and the connectivity. In contrast to the depression of F-v/F-m (35 %) and the rise of non-photochemical quenching (similar to 1.6), we observed an increase in effective absorption cross-section (20 %), Hill reaction (30 %), photosynthetic oxygen evolution (80 %), and electron transport rate estimated from the Chl fluorescence analysis (80 %). We showed an inconsistency in the presently used interpretation schemes, and ascribe the discrepancy between the increase of effective absorption cross-section and the photosynthetic activities on one side and the effective nonphotochemical quenching on the other side to the build-up of a quenching mechanism which dissipates energy in closed reaction centres. Such a type of quenching changes the ratio between thermal dissipation and fluorescence without any effect on photochemical yield. In this case the F-v/F-m ratio cannot be used as a measure of the maximum photochemical yield of PS2.||Notes:||Acad Sci Czech Republ, Inst Microbiol, Dept Autotroph Microorganisms, Trebon 37981, Czech Republic. Univ S Bohemia, Dept Plant Physiol, Ceske Budejovice 37005, Czech Republic. Limburgs Univ Ctr, Dept SBG, Lab Bot, B-3590 Diepenbeek, Belgium. Acad Sci Czech Republ, Inst Plant Mol Biol, Dept Photosynth, Ceske Budejovice 37005, Czech Republic.Koblizek, M, Acad Sci Czech Republ, Inst Microbiol, Dept Autotroph Microorganisms, Trebon 37981, Czech Republic.email@example.com||Keywords:||chlorophyll fluorescence; photochemical yield; non-photochemical quenching; connectivity; electron transport rate||Document URI:||http://hdl.handle.net/1942/2995||ISI #:||000085348900014||Type:||Journal Contribution||Validations:||ecoom 2001|
|Appears in Collections:||Research publications|
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