Metabolic origin of acetaldehyde emitted by poplar (Populus tremula x P. alba) trees

Kreuzwieser, Jürgen; Scheerer, Ursula; Rennenberg, Heinz

doi:10.1093/jxb/50.335.757

Cited by 49 publications

(79 citation statements)

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“…Some groups have demonstrated that ethanol produced in the roots where anaerobic conditions are more prevalent is transported to the leaves where it is converted to acetaldehyde and acetate (Kreuzwieser et al, 1999(Kreuzwieser et al, , 2000Karl et al, 2002). Thus, this pathway found in aerobic tissue might be metabolizing compounds generated by hypoxic or postanoxic conditions (Zuckermann et al, 1997) in the roots.…”

Section: Discussionmentioning

confidence: 99%

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

2008

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The acs1 knockout mutant that has a disruption in the plastidic acetyl-coenzyme A (CoA) synthetase (ACS; At5g36880) gene was used to explore the role of this protein and plastidic acetate metabolism in Arabidopsis (Arabidopsis thaliana). Disruption of the ACS gene decreased ACS activity by 90% and largely blocked the incorporation of exogenous 14 C-acetate and 14 C-ethanol into fatty acids. Whereas the disruption had no significant effect on the synthesis of bulk seed triacylglycerols, the acs1 plants were smaller and flowered later. This suggests that the pyruvate dehydrogenase bypass provided by the aerobic fermentation pathway that converts pyruvate to acetate and probably on to fatty acids is important to the plants during normal growth. The role of ACS in destroying fermentative intermediates is supported by the increased sensitivity of the acs1 mutant to exogenous acetate, ethanol, and acetaldehyde compared to wild-type plants. Whereas these observations suggest that flux through the aerobic fermentation pathway is important, the reason for this flux is unclear. Interestingly, acetate is able to support high rates of plant growth on medium and this growth is blocked in the acs1 mutant.

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Section: Discussionmentioning

confidence: 99%

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

2008

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“…At low oxygen levels plant roots switch from their aerobic metabolism to fermentation for generating energy. Several studies on temperate tree species have shown that leaves emit ethanol and acetaldehyde as a physiological response to anaerobic conditions in the roots (MacDonald et al, 1989;Kreuzwieser et al, 1999;Holzinger et al, 2000). Switching to alcoholic fermentation involves the production of ethanol from pyruvate in a two-step process under action of the enzymes pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH).…”

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confidence: 99%

The effect of flooding on the exchange of the volatile C<sub>2</sub>-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

et al. 2008

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Abstract. The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid in relation to assimilation and transpiration was investigated with 2-3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited measurable emissions of any of the compounds, but rather low deposition of acetaldehyde and acetic acid was observed instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid were only observed from the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning suggest that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic Correspondence to: J. Kesselmeier (jks@mpch-mainz.mpg.de) oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted, though we can not totally exclude other production pathways. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (25-1700 nmol m −2 min −1 for ethanol and 5-500 nmol m −2 min −1 for acetaldehyde). Acetic acid emissions reached 12 nmol m −2 min −1 . The observed differences in emission rates between the tree species are discussed with respect to their root adaptive strategies to tolerate long term flooding, providing an indirect line of evidence that the root ethanol production is a major factor determining the foliar emissions. Species which develop morphological root structures allowing for enhanced root aeration produced less ethanol and showed much lower emissions compared to species which lack gas transporting systems, and respond to flooding with substantially enhanced fermentation rates and a non-trivial loss of carbon to the atmosphere. The pronounced differences in the relative emissions of ethanol to acetaldehyde and acetic acid between the tree species indicate that not only the ethanol production in the roots but also the metabolic conversion in the leaf is an important factor determining the release of these compounds to the atmosphere.

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“…Metabolic attempts to remove ethanol involve translocation in the xylem and volatilization. Ethanol fed to leaves, or translocated from the roots, results in release of volatile acetaldehyde (Kreuzwieser et al, 1999). However, ethanol in the xylem increases from 0 to 12 mM during 6 h flooding, but only approx.…”

Section: Anaerobic Stress and Flooding Tolerance Of Plantsmentioning

confidence: 99%

“…Differential accumulation of ethanol has been proposed as a potential cause of observed species-specific differences in flooding tolerance (Crawford, 1982). Although plants respond to physiologically relevant ethanol concentrations (Perata & Alpi, 1993), these effects are now believed to be due to conversion of ethanol to acetaldehyde (Perata & Alpi, 1993, Kreuzwieser et al, 1999. Plant cells can generate ethanol under field conditions due to flooding of roots (Crawford, 1982 ;Kreuzwieser et al, 1999) or when stomata are closed in the dark and respiration consumes available oxygen (MacDonald & Kimmerer, 1993).…”

Section: Anaerobic Stress and Flooding Tolerance Of Plantsmentioning

confidence: 99%

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Tansley Review No. 118

Kingston‐Smith

Theodorou

2000

New Phytologist

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It is generally assumed that breakdown of plant material in the rumen is a process mediated by gut microorganisms. This view arose because of the identification of a pre-gastric fermentation in the rumen, brought about by a large and diverse microbial population. The extensive use of dried and ground feed particles in forage evaluation might have helped to promote this assumption. However, although the assumption might be correct in animals feeding on conserved forage (hay and silage) where the cells of ingested forage are dead, it is possible that with grazed (living) forage, the role played by plant enzymes in the rumen has been overlooked. In a grazing situation, plant cells that remain intact on entering the rumen are not inert, but will respond to the perceived stresses of the rumen environment for as long as they are metabolically viable. Metabolic adjustments could include anaerobic and heat-shock responses that could promote premature senescence, leading to remobilization of cell components, especially proteins. Moreover, contact of plant cells with colonizing microorganisms in the rumen might promote a type of hypersensitive response, in much the same way as it does outside the rumen. After fresh plant material enters the rumen and prior to extensive plant cell-wall degradation, there is often a phase of rapid proteolysis providing N in excess of that required to maintain the rumen microbial population. The inefficient use of this ingested N results in generation of ammonia and urea in exhaled breath and urine, which promotes welfare and environmental pollution concerns. Therefore an important research goal in livestock agriculture is to find ways of decreasing this initial rate of proteolysis in the rumen. This will benefit the farmer financially (through decreased use of feed supplements), but will also benefit the environment, as N pollution can adversely affect pasture diversity and ecology. This review considers the possible responses of plant metabolism to the rumen environment, and how such considerations could alter current thinking in ruminant agriculture.

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Metabolic origin of acetaldehyde emitted by poplar (Populus tremula x P. alba) trees

Cited by 49 publications

References 1 publication

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

The effect of flooding on the exchange of the volatile C<sub>2</sub>-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

Tansley Review No. 118

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Metabolic origin of acetaldehyde emitted by poplar (Populus tremula x P. alba) trees

Cited by 49 publications

References 1 publication

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

The effect of flooding on the exchange of the volatile C&lt;sub&gt;2&lt;/sub&gt;-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

Tansley Review No. 118

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The effect of flooding on the exchange of the volatile C<sub>2</sub>-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere