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Biogenic volatile organic compound and respiratory CO2 emissions after 13C-labeling: online tracing of C translocation dynamics in poplar plants.

Ghirardo A, Gutknecht J, Zimmer I, Brüggemann N, Schnitzler JP - PLoS ONE (2011)

Bottom Line: The daily C loss as BVOC ranged between 1.6% in mature leaves and 7.0% in young leaves.Non-isoprene BVOC accounted under light conditions for half of the BVOC C loss in young leaves and one-third in mature leaves.We quantified the plants' C loss as respiratory CO(2) and BVOC emissions, allowing in tandem with metabolic analysis to deepen our understanding of ecosystem C flux.

View Article: PubMed Central - PubMed

Affiliation: Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Garmisch-Partenkirchen, Germany.

ABSTRACT

Background: Globally plants are the primary sink of atmospheric CO(2), but are also the major contributor of a large spectrum of atmospheric reactive hydrocarbons such as terpenes (e.g. isoprene) and other biogenic volatile organic compounds (BVOC). The prediction of plant carbon (C) uptake and atmospheric oxidation capacity are crucial to define the trajectory and consequences of global environmental changes. To achieve this, the biosynthesis of BVOC and the dynamics of C allocation and translocation in both plants and ecosystems are important.

Methodology: We combined tunable diode laser absorption spectrometry (TDLAS) and proton transfer reaction mass spectrometry (PTR-MS) for studying isoprene biosynthesis and following C fluxes within grey poplar (Populus x canescens) saplings. This was achieved by feeding either (13)CO(2) to leaves or (13)C-glucose to shoots via xylem uptake. The translocation of (13)CO(2) from the source to other plant parts could be traced by (13)C-labeled isoprene and respiratory (13)CO(2) emission.

Principal finding: In intact plants, assimilated (13)CO(2) was rapidly translocated via the phloem to the roots within 1 hour, with an average phloem transport velocity of 20.3±2.5 cm h(-1). (13)C label was stored in the roots and partially reallocated to the plants' apical part one day after labeling, particularly in the absence of photosynthesis. The daily C loss as BVOC ranged between 1.6% in mature leaves and 7.0% in young leaves. Non-isoprene BVOC accounted under light conditions for half of the BVOC C loss in young leaves and one-third in mature leaves. The C loss as isoprene originated mainly (76-78%) from recently fixed CO(2), to a minor extent from xylem-transported sugars (7-11%) and from photosynthetic intermediates with slower turnover rates (8-11%).

Conclusion: We quantified the plants' C loss as respiratory CO(2) and BVOC emissions, allowing in tandem with metabolic analysis to deepen our understanding of ecosystem C flux.

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Net assimilation and respiratory CO2 emissions of intact poplar plants upon 13CO2 feeding.(A) Calculated δ13C of respired CO2 in the absence of net CO2 assimilation, assimilation rate of (B) 13CO2 and (C) 12CO2 of the mature 13CO2-fumigated leaf (black symbols), a younger fully expanded leaf (red), the apical bud with enclosed young leaves (green) of intact plants. (B) Release of CO2 from root systems immersed in hydroponic solution (blue). Calculated respiratory δ13C of roots during the period of 13CO2 labeling could not be presented (see Materials and Methods), they were replaced instead by sigmoidal fitted data (SigmaPlot v9.0, CA, USA; equation “sigmoid, 3 parameters”; R2 = 0.9997) shown in black. The labeling period is shown in orange, the period of stress (absence of CO2) by a blue background, and the dark periods are marked grey. Note that the stress period and the last dark period overlap. Data represent the mean of 3 experiments ± s.e.
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pone-0017393-g002: Net assimilation and respiratory CO2 emissions of intact poplar plants upon 13CO2 feeding.(A) Calculated δ13C of respired CO2 in the absence of net CO2 assimilation, assimilation rate of (B) 13CO2 and (C) 12CO2 of the mature 13CO2-fumigated leaf (black symbols), a younger fully expanded leaf (red), the apical bud with enclosed young leaves (green) of intact plants. (B) Release of CO2 from root systems immersed in hydroponic solution (blue). Calculated respiratory δ13C of roots during the period of 13CO2 labeling could not be presented (see Materials and Methods), they were replaced instead by sigmoidal fitted data (SigmaPlot v9.0, CA, USA; equation “sigmoid, 3 parameters”; R2 = 0.9997) shown in black. The labeling period is shown in orange, the period of stress (absence of CO2) by a blue background, and the dark periods are marked grey. Note that the stress period and the last dark period overlap. Data represent the mean of 3 experiments ± s.e.

Mentions: Furthermore, in the absence of net CO2 assimilation δ13C of plant respiratory CO2 was calculated as follows:where δ13Cout, δ13Cin, [CO2]out and [CO2]in are referred to δ13C values and CO2 concentrations of the cuvette outlet and inlet air, respectively; δ13C [‰]  =  (Rsa/Rref − 1) × 1000, related to Vienna Pee Dee Belemnite (VPDB), with Rsa and Rref as the sample and reference isotope ratios, respectively. No CO2 flux measurements for the fumigated mature leaf were possible during the 13CO2 labeling periods, as 13C/12C isotope ratio of the 13CO2 used was far beyond the detection range of the instrument. For experiments with intact plants, a 13C memory effect was observed in the TDLAS measurements of the other plant parts during the period of 13CO2 labeling. Therefore, respiratory δ13C of roots could not be precisely determined during fumigation and, thus, data were omitted (see Fig. 2A). Net CO2 assimilation rates were calculated according to von Caemmerer & Farquhar [26].


Biogenic volatile organic compound and respiratory CO2 emissions after 13C-labeling: online tracing of C translocation dynamics in poplar plants.

Ghirardo A, Gutknecht J, Zimmer I, Brüggemann N, Schnitzler JP - PLoS ONE (2011)

Net assimilation and respiratory CO2 emissions of intact poplar plants upon 13CO2 feeding.(A) Calculated δ13C of respired CO2 in the absence of net CO2 assimilation, assimilation rate of (B) 13CO2 and (C) 12CO2 of the mature 13CO2-fumigated leaf (black symbols), a younger fully expanded leaf (red), the apical bud with enclosed young leaves (green) of intact plants. (B) Release of CO2 from root systems immersed in hydroponic solution (blue). Calculated respiratory δ13C of roots during the period of 13CO2 labeling could not be presented (see Materials and Methods), they were replaced instead by sigmoidal fitted data (SigmaPlot v9.0, CA, USA; equation “sigmoid, 3 parameters”; R2 = 0.9997) shown in black. The labeling period is shown in orange, the period of stress (absence of CO2) by a blue background, and the dark periods are marked grey. Note that the stress period and the last dark period overlap. Data represent the mean of 3 experiments ± s.e.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046154&req=5

pone-0017393-g002: Net assimilation and respiratory CO2 emissions of intact poplar plants upon 13CO2 feeding.(A) Calculated δ13C of respired CO2 in the absence of net CO2 assimilation, assimilation rate of (B) 13CO2 and (C) 12CO2 of the mature 13CO2-fumigated leaf (black symbols), a younger fully expanded leaf (red), the apical bud with enclosed young leaves (green) of intact plants. (B) Release of CO2 from root systems immersed in hydroponic solution (blue). Calculated respiratory δ13C of roots during the period of 13CO2 labeling could not be presented (see Materials and Methods), they were replaced instead by sigmoidal fitted data (SigmaPlot v9.0, CA, USA; equation “sigmoid, 3 parameters”; R2 = 0.9997) shown in black. The labeling period is shown in orange, the period of stress (absence of CO2) by a blue background, and the dark periods are marked grey. Note that the stress period and the last dark period overlap. Data represent the mean of 3 experiments ± s.e.
Mentions: Furthermore, in the absence of net CO2 assimilation δ13C of plant respiratory CO2 was calculated as follows:where δ13Cout, δ13Cin, [CO2]out and [CO2]in are referred to δ13C values and CO2 concentrations of the cuvette outlet and inlet air, respectively; δ13C [‰]  =  (Rsa/Rref − 1) × 1000, related to Vienna Pee Dee Belemnite (VPDB), with Rsa and Rref as the sample and reference isotope ratios, respectively. No CO2 flux measurements for the fumigated mature leaf were possible during the 13CO2 labeling periods, as 13C/12C isotope ratio of the 13CO2 used was far beyond the detection range of the instrument. For experiments with intact plants, a 13C memory effect was observed in the TDLAS measurements of the other plant parts during the period of 13CO2 labeling. Therefore, respiratory δ13C of roots could not be precisely determined during fumigation and, thus, data were omitted (see Fig. 2A). Net CO2 assimilation rates were calculated according to von Caemmerer & Farquhar [26].

Bottom Line: The daily C loss as BVOC ranged between 1.6% in mature leaves and 7.0% in young leaves.Non-isoprene BVOC accounted under light conditions for half of the BVOC C loss in young leaves and one-third in mature leaves.We quantified the plants' C loss as respiratory CO(2) and BVOC emissions, allowing in tandem with metabolic analysis to deepen our understanding of ecosystem C flux.

View Article: PubMed Central - PubMed

Affiliation: Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Garmisch-Partenkirchen, Germany.

ABSTRACT

Background: Globally plants are the primary sink of atmospheric CO(2), but are also the major contributor of a large spectrum of atmospheric reactive hydrocarbons such as terpenes (e.g. isoprene) and other biogenic volatile organic compounds (BVOC). The prediction of plant carbon (C) uptake and atmospheric oxidation capacity are crucial to define the trajectory and consequences of global environmental changes. To achieve this, the biosynthesis of BVOC and the dynamics of C allocation and translocation in both plants and ecosystems are important.

Methodology: We combined tunable diode laser absorption spectrometry (TDLAS) and proton transfer reaction mass spectrometry (PTR-MS) for studying isoprene biosynthesis and following C fluxes within grey poplar (Populus x canescens) saplings. This was achieved by feeding either (13)CO(2) to leaves or (13)C-glucose to shoots via xylem uptake. The translocation of (13)CO(2) from the source to other plant parts could be traced by (13)C-labeled isoprene and respiratory (13)CO(2) emission.

Principal finding: In intact plants, assimilated (13)CO(2) was rapidly translocated via the phloem to the roots within 1 hour, with an average phloem transport velocity of 20.3±2.5 cm h(-1). (13)C label was stored in the roots and partially reallocated to the plants' apical part one day after labeling, particularly in the absence of photosynthesis. The daily C loss as BVOC ranged between 1.6% in mature leaves and 7.0% in young leaves. Non-isoprene BVOC accounted under light conditions for half of the BVOC C loss in young leaves and one-third in mature leaves. The C loss as isoprene originated mainly (76-78%) from recently fixed CO(2), to a minor extent from xylem-transported sugars (7-11%) and from photosynthetic intermediates with slower turnover rates (8-11%).

Conclusion: We quantified the plants' C loss as respiratory CO(2) and BVOC emissions, allowing in tandem with metabolic analysis to deepen our understanding of ecosystem C flux.

Show MeSH
Related in: MedlinePlus