title: Genetic decrease in fatty acid unsaturation of phosphatidylglycerol increased photoinhibition of photosystem I at low temperature in tobacco leaves.
abstract: Leaves of transgenic tobacco plants with decreased levels of fatty acid unsaturation in phosphatidylglycerol (PG) exhibited a slightly lower level of the steady state oxidation of the photosystem I (PSI) reaction center P700 (P700(+)) than wild-type plants. The PSI photochemistry of wild-type plants was only marginally affected by high light treatments. Surprisingly, all plants of transgenic lines exhibited much higher susceptibility to photoinhibition of PSI than wild-type plants. This was accompanied by a 2.5-fold faster re-reduction rate of P700(+) in the dark, indicating a higher capacity for cyclic electron flow around PSI in high light treated transgenic leaves. This was associated with a much higher intersystem electron pool size suggesting over-reduction of the PQ pool in tobacco transgenic lines with altered PG unsaturation compared to wild-type plants. The physiological role of PG unsaturation in PSI down-regulation and modulation of the capacity of PSI-dependent cyclic electron flows and distribution of excitation light energy in tobacco plants under photoinhibitory conditions at low temperatures is discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, Canada. aivanov@uwo.ca
authors.forename: A G
authors.initials: AG
authors.lastname: Ivanov
authors.forename: S I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: N P A
authors.initials: NP
authors.lastname: Huner
authors.forename: N
authors.initials: N
authors.lastname: Murata
mesh_terms: D003080:Cold Temperature; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008027:Light; D010715:Phosphatidylglycerols / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D010715:Phosphatidylglycerols; D045331:Photosystem I Protein Complex