Article (Scientific journals)
PSI Mehler reaction is the main alternative photosynthetic electron pathway in Symbiodinium sp., symbiotic dinoflagellates of cnidarians
Roberty, Stéphane; Bailleul, Benjamin; Berne, Nicolas et al.
2014In New Phytologist, 204 (1), p. 81-91
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Keywords :
Water water cycle; chlororespiration; coral bleaching; mitochondrial respiration; cyclic electron flow
Abstract :
[en] • Photosynthetic organisms have evolved various photoprotective and regulatory mechanisms to cope with changing and high light intensities. The nature and relative amplitude of these mechanisms is matter of debate in dinoflagellates that live in symbiosis with cnidarians. In this work, the amplitude of photosynthetic alternative electron flows to oxygen (chlororespiration, Mehler reaction, mitochondrial respiration) and PSI cyclic electron flow were investigated in Symbiodinium clades A1, B1 and F1. • Cultured Symbiodinium strains were maintained semi-continuously under identical environmental conditions. Joint measurements of oxygen evolution, fluorescence emission, and absorption changes at specific wavelengths were used to evaluate PSI and PSII electron transfer rates (ETR). • A light-dependent and O2-dependent ETR was observed in all strains. This ETR involved PSII and PSI and was insensitive to addition of mitochondrial and carbon fixation inhibitors. • These results demonstrate that photoreduction of oxygen downstream of PSI by the so-called Mehler reaction is the main alternative electron sink at the onset and steady state of photosynthesis in all strains. This mechanism in Symbiodinium sustains significant levels of photosynthetic electron flux under high light, thus acting as a photoprotective mechanism and increasing the ATP/NADPH ratio by the electron transfer chain.
Disciplines :
Biochemistry, biophysics & molecular biology
Phytobiology (plant sciences, forestry, mycology...)
Aquatic sciences & oceanology
Author, co-author :
Roberty, Stéphane  ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et physiologie des microalgues
Bailleul, Benjamin ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et physiologie des microalgues
Berne, Nicolas 
Franck, Fabrice  ;  Université de Liège - ULiège > Labo de Bioénergétique
Cardol, Pierre   ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et physiologie des microalgues
 These authors have contributed equally to this work.
Language :
English
Title :
PSI Mehler reaction is the main alternative photosynthetic electron pathway in Symbiodinium sp., symbiotic dinoflagellates of cnidarians
Publication date :
October 2014
Journal title :
New Phytologist
ISSN :
0028-646X
eISSN :
1469-8137
Publisher :
Blackwell Publishing, Oxford, United Kingdom
Volume :
204
Issue :
1
Pages :
81-91
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 28 May 2014

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