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Berlin Brandenburg

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  • Wiley (CrossRef)  (74)
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  • 1
    Language: English
    In: The New phytologist, February 2011, Vol.189(3), pp.659-77
    Description: Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O(2)-reduction and CO(2)-release can be approximated by Arrhenius kinetics, even though respiratory gas exchange of plants is the net effect of many constituent biochemical processes. Nonetheless, the classical Arrhenius equation must be modified to account for a dynamic response to measurement temperatures. We show that this dynamic response is readily explained by combining Arrhenius and Michaelis-Menten kinetics, as part of a fresh appraisal of metabolic interpretations of instantaneous temperature responses. In combination with recent experimental findings, we argue that control of mitochondrial electron flow is shared among cytochrome oxidase and alternative oxidase under in vivo conditions, and is continuously coordinated. In this way, upstream carbohydrate metabolism and downstream electron transport appear to be optimized according to the demand of ATP, TCA-cycle intermediates and anabolic reducing power under differing metabolic states. We provide a link to the 'Growth and Maintenance Paradigm' of respiration and argue that respiratory temperature responses can be used as a tool to probe metabolic states of plant tissue, such that we can learn more about the mechanisms that govern longer-term acclimatization responses of plant metabolism.
    Keywords: Carbohydrate Metabolism ; Energy Metabolism ; Temperature ; Acclimatization -- Physiology ; Plants -- Metabolism ; Stress, Physiological -- Physiology
    ISSN: 0028646X
    E-ISSN: 1469-8137
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  • 2
    In: New Phytologist, January 2015, Vol.205(1), pp.240-254
    Description: Overexpression of bacterial γ‐glutamylcysteine synthetase in the cytosol of Populus tremula × P. alba produces higher glutathione (GSH) concentrations in leaves, thereby indicating the potential for cadmium (Cd) phytoremediation. However, the net Cd2+ influx in association with H+/Ca2+, Cd tolerance, and the underlying molecular and physiological mechanisms are uncharacterized in these poplars. We assessed net Cd2+ influx, Cd tolerance and the transcriptional regulation of several genes involved in Cd2+ transport and detoxification in wild‐type and transgenic poplars. Poplars exhibited highest net Cd2+ influxes into roots at pH 5.5 and 0.1 mM Ca2+. Transgenics had higher Cd2+ uptake rates and elevated transcript levels of several genes involved in Cd2+ transport and detoxification compared with wild‐type poplars. Transgenics exhibited greater Cd accumulation in the aerial parts than wild‐type plants in response to Cd2+ exposure. Moreover, transgenic poplars had lower concentrations of O2˙− and H2O2; higher concentrations of total thiols, GSH and oxidized GSH in roots and/or leaves; and stimulated foliar GSH reductase activity compared with wild‐type plants. These results indicate that transgenics are more tolerant of 100 μM Cd2+ than wild‐type plants, probably due to the GSH‐mediated induction of the transcription of genes involved in Cd2+ transport and detoxification.
    Keywords: Antioxidant ; Cadmium C D ; Glutathione ; Ion Flux ; Oxidative Stress ; Phytoremediation ; Plasma Membrane H + ‐ Atp Ase ; P Opulus
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 3
    In: New Phytologist, October 2012, Vol.196(1), pp.162-172
    Description: • Increasing atmospheric concentrations of phytotoxic ozone (O3) can constrain growth and carbon sink strength of forest trees, potentially exacerbating global radiative forcing. Despite progress in the conceptual understanding of the impact of O3 on plants, it is still difficult to detect response patterns at the leaf level. • Here, we employed principal component analysis (PCA) to analyse a database containing physiological leaf‐level parameters of 60‐yr‐old Fagus sylvatica (European beech) trees. Data were collected over two climatically contrasting years under ambient and twice‐ambient O3 regimes in a free‐air forest environment. • The first principal component (PC1) of the PCA was consistently responsive to O3 and crown position within the trees over both years. Only a few of the original parameters showed an O3 effect. PC1 was related to parameters indicative of oxidative stress signalling and changes in carbohydrate metabolism. PC1 correlated with cumulative O3 uptake over preceding days. • PC1 represents an O3‐responsive multivariate pattern detectable in the absence of consistently measurable O3 effects on individual leaf‐level parameters. An underlying effect of O3 on physiological processes is indicated, providing experimental confirmation of theoretical O3 response patterns suggested previously.
    Keywords: Cumulative O 3 Uptake ; Fagus Sylvatica European Beech ; Multivariate Analysis ; Ozone O 3 ; Principal Component Analysis Pca
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 4
    In: New Phytologist, December 2012, Vol.196(4), pp.1074-1085
    Description: High concentrations of sulfur dioxide (SO2) as an air pollutant, and its derivative sulfite, cause abiotic stress that can lead to cell death. It is currently unknown to what extent plant fumigation triggers specific transcriptional responses. To address this question, and to test the hypothesis that sulfite oxidase (SO) is acting in SO2 detoxification, we compared Arabidopsis wildtype (WT) and SO knockout lines (SO‐KO) facing the impact of 600 nl l−1 SO2, using RNAseq to quantify absolute transcript abundances. These transcriptome data were correlated to sulfur metabolism‐related enzyme activities and metabolites obtained from identical samples in a previous study. SO‐KO plants exhibited remarkable and broad regulative responses at the mRNA level, especially in transcripts related to sulfur metabolism enzymes, but also in those related to stress response and senescence. Focusing on SO regulation, no alterations were detectable in the WT, whereas in SO‐KO plants we found up‐regulation of two splice variants of the SO gene, although this gene is not functional in this line. Our data provide evidence for the highly specific coregulation between SO and sulfur‐related enzymes like APS reductase, and suggest two novel candidates for involvement in SO2 detoxification: an apoplastic peroxidase, and defensins as putative cysteine mass storages.
    Keywords: Arabidopsis Knockout Mutants ; Cluster Analyses ; Gene Ontology ; ‐Deep‐Sequencing ; Fumigation ; Sulfate Assimilation ; Sulfite Detoxification ; Sulfite Oxidase
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 5
    In: New Phytologist, April 2012, Vol.194(1), pp.129-141
    Description: • Salinity causes osmotic stress and limits biomass production of plants. The goal of this study was to investigate mechanisms underlying hydraulic adaptation to salinity. • Anatomical, ecophysiological and transcriptional responses to salinity were investigated in the xylem of a salt‐sensitive (Populus × canescens) and a salt‐tolerant species (Populus euphratica). • Moderate salt stress, which suppressed but did not abolish photosynthesis and radial growth in P. × canescens, resulted in hydraulic adaptation by increased vessel frequencies and decreased vessel lumina. Transcript abundances of a suite of genes (FLA, COB‐like, BAM, XET, etc.) previously shown to be activated during tension wood formation, were collectively suppressed in developing xylem, whereas those for stress and defense‐related genes increased. A subset of cell wall‐related genes was also suppressed in salt‐exposed P. euphratica, although this species largely excluded sodium and showed no anatomical alterations. Salt exposure influenced cell wall composition involving increases in the lignin : carbohydrate ratio in both species. • In conclusion, hydraulic stress adaptation involves cell wall modifications reciprocal to tension wood formation that result in the formation of a novel type of reaction wood in upright stems named ‘pressure wood’. Our data suggest that transcriptional co‐regulation of a core set of genes determines reaction wood composition.
    Keywords: Arabinogalactan Protein ; Biomass ; Carbohydrate ; Fasciclin‐Like Protein ; Phloem ; Salt Transcriptome ; Wood ; Xylem
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 6
    In: New Phytologist, April 2017, Vol.214(2), pp.597-606
    Description: The present study was performed to elucidate the fate of carbon (C) and nitrogen (N) derived from protein of prey caught by carnivorous Dionaea muscipula. For this, traps were fed 13C/15N‐glutamine (Gln). The release of 13CO2 was continuously monitored by isotope ratio infrared spectrometry. After 46 h, the allocation of C and N label into different organs was determined and tissues were subjected to metabolome, proteome and transcriptome analyses. Nitrogen of Gln fed was already separated from its C skeleton in the decomposing fluid secreted by the traps. Most of the Gln‐C and Gln‐N recovered inside plants were localized in fed traps. Among nonfed organs, traps were a stronger sink for Gln‐C compared to Gln‐N, and roots were a stronger sink for Gln‐N compared to Gln‐C. A significant amount of the Gln‐C was respired as indicated by 13C‐CO2 emission, enhanced levels of metabolites of respiratory Gln degradation and increased abundance of proteins of respiratory processes. Transcription analyses revealed constitutive expression of enzymes involved in Gln metabolism in traps. It appears that prey not only provides building blocks of cellular constituents of carnivorous Dionaea muscipula, but also is used for energy generation by respiratory amino acid degradation.
    Keywords: Amino Acid Catabolism ; Carbon Partitioning ; Dionaea Muscipula Venus Flytrap ; Glutamine ; Nitrogen N Partitioning ; Plant Carnivory ; Respiratory Degradation
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 7
    In: New Phytologist, October 1998, Vol.140(2), pp.319-329
    Description: Beech nuts ( L.) were germinated and grown in soil inoculated with the ectomycorrhizal fungus or for 18–20 wk. The success of mycorrhizal infection was monitored by measuring the ergosterol contents of the mycorrhizas. Ergosterol levels ranged from 122±23 μg g d. wt ( mycorrhizas) to 94±36 μg g d. wt ( mycorrhizas), indicating that ectomycorrhizal symbiosis was established. In root incubation chambers, rates of sulphate uptake and the xylem loading of sulphate of excised mycorrhizas were investigated. Both types of mycorrhizas showed saturation kinetics in external sulphate concentrations from 2·5–1000 μmol l. Linearization of these kinetics revealed two phases with low apparent ( mycorrhizas: 15±3 μmol l; mycorrhizas: 13±3 μmol l) and ( mycorrhizas: 19±3 nmol h g f. wt; mycorrhizas: 25±4 nmol h g f. wt) at low external sulphate concentrations and significantly higher kinetic constants at higher sulphate supplies. Relative xylem loading, i.e. the portion of sulphate loaded into the xylem that was taken up, remained constant over the entire concentration range investigated (. 4–7% of the sulphate taken up). If trees were supplied for 72 h with different N and sulphur concentrations, both uptake of sulphate and relative xylem loading were unaffected by sulphur availability, but modulated by N supply. Nitrogen depletion diminished the rates of sulphate uptake in and mycorrhizas. In response to higher N availability combined with sulphur depletion, sulphate uptake of mycorrhizas, but not of mycorrhizas, increased. Organic compounds considered to be possible signals for the regulation of sulphate uptake were fed to excised mycorrhizas. ‐Cysteine but not ‐methionine and glutathione (γ‐Glu‐Cys‐Gly) inhibited sulphate uptake of the two mycorrhizas and xylem loading of sulphate was stimulated rather than inhibited by ‐Cys in both types. In mycorrhizas glutathione had a similar effect. ‐Acetyl‐‐serine (OAS), a precursor of ‐cysteine, stimulated sulphate uptake, but did not affect xylem loading. Apparently, OAS, generated in N metabolism, and ‐cysteine, a product of assimilatory sulphate reduction, act as antagonists, together mediating regulation of sulphate uptake.
    Keywords: Sulphate Uptake ; Xylem Loading Of Sulphate ; Ectomycorrhizas ; L. Beech
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 8
    In: Plant, Cell & Environment, June 2018, Vol.41(6), pp.1369-1382
    Description: We used instantaneous temperature responses of CO‐respiration to explore temperature acclimation dynamics for grown with differing nitrogen supply. A reduction in ambient temperature from 23 to 19 °C reduced light‐saturated photosynthesis by 25% but increased respiratory capacity by 30%. Changes in respiratory capacity were not reversed after temperatures were subsequently increased to 27 °C. Temperature sensitivity of respiration measured at prevalent ambient temperature varied little between temperature treatments but was significantly reduced from ~105 kJ mol when supply of N was weak, to ~70 kJ mol when it was strong. Temperature sensitivity of respiration measured across a broader temperature range (20–40 °C) could be fully described by 2 exponent parameters of an Arrhenius‐type model (i.e., activation energy of respiration at low reference temperature and a parameter describing the temperature dependence of activation energy). These 2 parameters were strongly correlated, statistically explaining 74% of observed variation. Residual variation was linked to treatment‐induced changes in respiration at low reference temperature or respiratory capacity. Leaf contents of starch and soluble sugars suggest that respiratory capacity varies with source‐sink imbalances in carbohydrate utilization, which in combination with shifts in carbon‐flux mode, serve to maintain homeostasis of respiratory temperature sensitivity at prevalent growth temperature. Leaf respiration plays a central role in the carbon‐balance of plants and ecosystems, but algorithms describing respiratory acclimation to environmental cues are presently lacking. This study explores temporal variation in respiration parameters derived from an extended Arrhenius‐equation, elicited by short‐term changes in growth temperature and differing nitrogen nutrition. It is shown that three parameters are suited to capture the entire variation of acclimation responses.
    Keywords: Acclimation ; C/N‐Balance ; Eucalyptus Grandis ; Flux Regulation ; Homeostasis ; Temperature Response
    ISSN: 0140-7791
    E-ISSN: 1365-3040
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  • 9
    In: Plant, Cell & Environment, May 2013, Vol.36(5), pp.1019-1026
    Description: Signals controlling the competitive interactions for nitrogen between plants and soil microorganisms in the rhizosphere are to date mainly unknown, thus, we investigated the effects of rhizospheric concentration with varying soil availability on uptake and metabolism in fine roots of Scots pine seedlings. Our results show for the first time that affected uptake by seedlings dependent on source and soil availability. The commonly accepted suppression of nitrate uptake in the presence of ammonium and glutamine was overruled at high . This study also provides first evidence for the effects of on nitrate and arginine uptake in a tree species and that rhizospheric does not only affect deciduous trees (, beech), but also coniferous tree species (, pine). We investigated the interaction of rhizospheric nitric oxide () concentration (i.e. low, ambient or high) and soil nitrogen () availability (i.e. low or high) with organic and inorganic uptake by fine roots of  . seedlings by feeding experiments under controlled conditions. metabolites in fine roots were analysed to link uptake to nutrition. affected uptake depending on source and soil availability. The suppression of nitrate uptake in the presence of ammonium and glutamine was overruled by high . The effects of on uptake with increasing availability showed different patterns: (1) increasing uptake regardless of concentration (i.e. ammonium); (2) increasing uptake only with high concentration (i.e. nitrate and arginine); and (3) decreasing uptake (i.e. glutamine). At low availability and high nitrate accumulated in the roots indicating insufficient substrates for nitrate reduction or its storage in root vacuoles. Individual amino acid concentrations were negatively affected with increasing (i.e. asparagine and glutamine with low availability, serine and proline with high availability). In conclusion, this study provides first evidence that affects uptake and metabolism in a conifer.
    Keywords: Ammonium ; Arginine ; Glutamine ; Inorganic Uptake ; Nitrate ; Fumigation ; Organic Uptake
    ISSN: 0140-7791
    E-ISSN: 1365-3040
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  • 10
    In: New Phytologist, September 2000, Vol.147(3), pp.539-560
    Description: The dynamic‐chamber technique was used to investigate the correlation between NH and NO fluxes and different climatic and physiological parameters: air temperature; relative air humidity; photosynthetic photon fluence rate; NH and NO concentrations; transpiration rate; leaf conductance for water vapour; and photosynthetic activity. The experiments were performed with twigs from the sun crown of mature beech trees () at a field site (Höglwald, Germany), and with 12‐wk‐old beech seedlings under controlled conditions. Both sets of experiments showed that NO and NH fluxes depended linearly on NO and NH concentration, respectively, in the concentration ranges representative for the field site studied, and on water‐vapour conductance as a measure for stomatal aperture. The NO compensation point determined in the field studies (the atmospheric NO concentration with no net NO flux) was 1.8–1.9 nmol mol. The NH compensation point varied between 3.3 and 3.5 nmol mol in the field experiments, and was 3.0 nmol mol in the experiments under controlled conditions. The climatic factors and PPFR were found to influence both NO and NH fluxes indirectly, by changing stomatal conductance. Whilst NO flux showed a response to changing relative humidity that could be explained by altered stomatal conductance, increased NH flux with increasing relative humidity (〉50%) depended on other factors. The exchange of NO between above‐ground parts of beech trees and the atmosphere could be explained exclusively by uptake or emission of NO through the stomata, as indicated by the quotient between measured and predicted NO conductance of approx. 1 under all environmental conditions examined. Neither internal mesophyll resistances nor additional sinks could be observed for adult trees or for beech seedlings. By contrast, the patterns of NH flux could not be explained by an exclusive exchange of NH through the stomata. Deposition into additional sinks on the leaf surface, as indicated by an increase in the quotient between measured and predicted NH conductance, gained importance in high air humidity, when the stomata were closed or nearly closed and/or when atmospheric NH concentrations were high. Although patterns of NH gas exchange did not differ between different months or years at high NH concentrations (. 140 nmol mol), it must be assumed that emission or deposition fluxes at low ambient NH concentration (0.8 and 4.5 nmol mol) might vary significantly with time because of variation in the NH compensation point.
    Keywords: Dry Deposition ; Stomatal Conductance ; Cuticular Deposition ; Compensation Point
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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