title: Involvement of respiratory processes in the transient knockout of net CO2 uptake in Mimosa pudica upon heat stimulation.
abstract: Leaf photosynthesis of the sensitive plant Mimosa pudica displays a transient knockout in response to electrical signals induced by heat stimulation. This study aims at clarifying the underlying mechanisms, in particular, the involvement of respiration. To this end, leaf gas exchange and light reactions of photosynthesis were assessed under atmospheric conditions largely eliminating photorespiration by either elevated atmospheric CO2 or lowered O2 concentration (i.e. 2000 μmol mol(-1) or 1%, respectively). In addition, leaf gas exchange was studied in the absence of light. Under darkness, heat stimulation caused a transient increase of respiratory CO2 release simultaneously with stomatal opening, hence reflecting direct involvement of respiratory stimulation in the drop of the net CO2 uptake rate. However, persistence of the transient decline in net CO2 uptake rate under illumination and elevated CO2 or 1% O2 makes it unlikely that photorespiration is the metabolic origin of the respiratory CO2 release. In conclusion, the transient knockout of net CO2 uptake is at least partially attributed to an increased CO2 release through mitochondrial respiration as stimulated by electrical signals. Putative CO2 limitation of Rubisco due to decreased activity of carbonic anhydrase was ruled out as the photosynthesis effect was not prevented by elevated CO2 .
authors.affiliation: Institute for Wood Biology, Center of Wood Sciences, Universität Hamburg, Leuschnerstrasse 91d, 21031, Hamburg, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Lautner
authors.forename: Michaela
authors.initials: M
authors.lastname: Stummer
authors.forename: Rainer
authors.initials: R
authors.lastname: Matyssek
authors.forename: Jörg
authors.initials: J
authors.lastname: Fromm
authors.forename: Thorsten E E
authors.initials: TE
authors.lastname: Grams
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism; D003624:Darkness; D004560:Electricity; D006358:Hot Temperature; D008027:Light; D031298:Mimosa / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D010100:Oxygen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D054046:Plant Stomata / Q000502:physiology / Q000528:radiation effects; D018526:Plant Transpiration / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D014867:Water / Q000502:physiology
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water; D002734:Chlorophyll; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D002256:Carbonic Anhydrases; D010100:Oxygen
keywords: electrical signals; leaf gas exchange; photorespiration; respiration; stomatal aperture