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  • New Phytologist
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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
    Language: English
    In: New Phytologist, Feb, 2011, Vol.189, p.659(19)
    Description: To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1469-8137.2010.03576.x Byline: Jorg Kruse (1), Heinz Rennenberg (1), Mark A. Adams (2) Keywords: acclimatization; Arrhenius kinetics; Q-model; respiration; temperature response Abstract: Contents Summary Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O.sub.2-reduction and CO.sub.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. Author Affiliation: (1)Institute of Forest Botany, Chair of Tree Physiology, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 53-54, D-79110 Freiburg, Germany (2)Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, NSW 2006, Australia Article History: Received: 6 July 2010, Accepted: 29 October 2010 Article note: Author for correspondence:, Jorg Kruse, Tel: +49 (0) 761 203 8300, Fax: +49 (0) 761 203 8302, Email: joerg.kruse@ctp.uni-freiburg.de
    Keywords: Carbohydrate Metabolism -- Physiological Aspects ; Cytochrome Oxidase -- Physiological Aspects
    ISSN: 0028-646X
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: New Phytologist, Feb, 2011, Vol.189, p.659(19)
    Description: To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1469-8137.2010.03576.x Byline: Jorg Kruse (1), Heinz Rennenberg (1), Mark A. Adams (2) Keywords: acclimatization; Arrhenius kinetics; Q-model; respiration; temperature response Abstract: Contents Summary Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O.sub.2-reduction and CO.sub.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. Author Affiliation: (1)Institute of Forest Botany, Chair of Tree Physiology, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 53-54, D-79110 Freiburg, Germany (2)Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, NSW 2006, Australia Article History: Received: 6 July 2010, Accepted: 29 October 2010 Article note: Author for correspondence:, Jorg Kruse, Tel: +49 (0) 761 203 8300, Fax: +49 (0) 761 203 8302, Email: joerg.kruse@ctp.uni-freiburg.de
    Keywords: Carbohydrate Metabolism -- Physiological Aspects ; Cytochrome Oxidase -- Physiological Aspects
    ISSN: 0028-646X
    Source: Cengage Learning, Inc.
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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    In: New Phytologist, February 2015, Vol.205(3), pp.1320-1329
    Description: Carnivorous Dionaea muscipula operates active snap traps for nutrient acquisition from prey; so what is the role of D. muscipula's reduced root system? We studied the capacity for nitrogen (N) acquisition via traps, and its effect on plant allometry; the capacity of roots to absorb NO3−, NH4+ and glutamine from the soil solution; and the fate and interaction of foliar‐ and root‐acquired N. Feeding D. muscipula snap traps with insects had little effect on the root : shoot ratio, but promoted petiole relative to trap growth. Large amounts of NH4+ and glutamine were absorbed upon root feeding. The high capacity for root N uptake was maintained upon feeding traps with glutamine. High root acquisition of NH4+ was mediated by 2.5‐fold higher expression of the NH4+ transporter DmAMT1 in the roots compared with the traps. Electrophysiological studies confirmed a high constitutive capacity for NH4+ uptake by roots. Glutamine feeding of traps inhibited the influx of 15N from root‐absorbed 15N/13C‐glutamine into these traps, but not that of 13C. Apparently, fed traps turned into carbon sinks that even acquired organic carbon from roots. N acquisition at the whole‐plant level is fundamentally different in D. muscipula compared with noncarnivorous species, where foliar N influx down‐regulates N uptake by roots.
    Keywords: Ammonium ; Glutamine ; Nitrogen N Nutrition ; Plant Carnivory ; Root : shoot Integration
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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