title: Cold acclimation and BnCBF17-over-expression enhance photosynthetic performance and energy conversion efficiency during long-term growth of Brassica napus under elevated CO2 conditions.
abstract: The effects of cold acclimation and long-term elevated CO(2) on photosynthetic performance of wild-type (WT) and BnCBF17-over-expressing line of Brassica napus cv. Westar (BnCBF17-OE) grown at either 20/16 °C (non-acclimated) or 5/5 °C (cold acclimated) and at either ambient (380 μmol C mol(-1)) or elevated (700 μmol C mol(-1)) CO(2) were studied. Compared with non-acclimated WT, the BnCBF17-OE grown at 20 °C mimicked the effects of cold acclimation on WT B. napus with respect to compact dwarf phenotype and increased rates of light-saturated CO(2) assimilation and photosynthetic electron transport. This was associated with enhanced energy conversion efficiency into biomass as assessed by decreased excitation pressure coupled to decreased dependence on non-photochemical energy dissipation for a given irradiance. Growth at elevated CO(2) decreased the light and CO(2)-saturated rates of photosynthesis by 30 % for non-acclimated WT relative to growth at ambient CO(2). This was associated with inhibition in electron transport rates (20 %), decrease in amount of rbcL (35 %) and cytosolic FBPase (70 %) and increased excitation pressure and non-photochemical quenching in elevated versus ambient CO(2)-grown non-acclimated WT. In contrast, light and CO(2)-saturated rates of photosynthesis, electron transport, excitation pressure, non-photochemical quenching and levels of rbcL, cytosolic FBPase and Lhcb1 were insensitive to growth under elevated CO(2) in BnCBF17-OE and cold-acclimated WT. Thus, BnCBF17-over-expression and cold acclimation maintain enhanced energy conversion efficiency and reduced sensitivity to feedback-limited photosynthesis during long-term growth of B. napus under elevated CO(2). Our results indicated that CBFs transcription factors regulate not only freezing tolerance but also has major whole plant effects.
authors: Department of Biology, The Biotron Centre for Experimental Climate Change Research, The University of Western Ontario, London, ON, N6A 5B7, Canada. kdahal@uwo.ca
authors: Keshav
authors: K
authors: Dahal
authors: Winona
authors: W
authors: Gadapati
authors: Leonid V
authors: LV
authors: Savitch
authors: Jas
authors: J
authors: Singh
authors: Norman P A
authors: NP
authors: Hüner
mesh_terms: D000064:Acclimatization; D029688:Brassica napus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D002245:Carbon Dioxide / Q000494:pharmacology; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D003080:Cold Temperature; D004579:Electron Transport; D004734:Energy Metabolism; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology; D030821:Plants, Genetically Modified
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D002245:Carbon Dioxide; D000077194:Chlorophyll A