title: Alternative electron transport mediated by flavodiiron proteins is operational in organisms from cyanobacteria up to gymnosperms.
abstract: Photo-reduction of O2to water mediated by flavodiiron proteins (FDPs) represents a safety valve for the photosynthetic electron transport chain in fluctuating light. So far, the FDP-mediated O2photo-reduction has been evidenced only in cyanobacteria and the moss Physcomitrella; however, a recent phylogenetic analysis of transcriptomes of photosynthetic organisms has also revealed the presence of FDP genes in several nonflowering plant groups. What remains to be clarified is whether the FDP-dependent O2photo-reduction is actually operational in these organisms. We have established a simple method for the monitoring of FDP-mediated O2photo-reduction, based on the measurement of redox kinetics of P700 (the electron donor of photosystem I) upon dark-to-light transition. The O2photo-reduction is manifested as a fast re-oxidation of P700. The validity of the method was verified by experiments with transgenic organisms, namely FDP knock-out mutants of Synechocystis and Physcomitrella and transgenic Arabidopsis plants expressing FDPs from Physcomitrella. We observed the fast P700 re-oxidation in representatives of all green plant groups excluding angiosperms. Our results provide strong evidence that the FDP-mediated O2photo-reduction is functional in all nonflowering green plant groups. This finding suggests a major change in the strategy of photosynthetic regulation during the evolution of angiosperms.
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University, 783 71, Olomouc, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Ilík
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University, 783 71, Olomouc, Czech Republic.
authors.forename: Andrej
authors.initials: A
authors.lastname: Pavlovič
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University, 783 71, Olomouc, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Kouřil
authors.affiliation: Department of Biology, University of Padova, 35131, Padova, Italy.
authors.forename: Alessandro
authors.identifier: http://orcid.org/0000-0003-4818-7778
authors.initials: A
authors.lastname: Alboresi
authors.affiliation: Department of Biology, University of Padova, 35131, Padova, Italy.
authors.forename: Tomas
authors.initials: T
authors.lastname: Morosinotto
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, 20014, Turku, Finland.
authors.forename: Yagut
authors.initials: Y
authors.lastname: Allahverdiyeva
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, 20014, Turku, Finland.
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, 606-8502, Kyoto, Japan.|CREST, Japan Science and Technology Agency, Chiyoda-ku, 102-0076, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, 606-8502, Kyoto, Japan.|CREST, Japan Science and Technology Agency, Chiyoda-ku, 102-0076, Tokyo, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Shikanai
mesh_terms: D000458:Cyanobacteria / Q000378:metabolism* / Q000528:radiation effects; D032462:Cycadopsida / Q000378:metabolism* / Q000528:radiation effects; D004579:Electron Transport; D005420:Flavoproteins / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000528:radiation effects; D010802:Phylogeny
chemical_list: D005420:Flavoproteins
keywords: O2 photo-reduction; alternative electron transport; dark-to-light transition; evolution of green plants; flavodiiron proteins; photosystem I; redox changes of P700