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  • 1. Cormier, Marc-André
    et al.
    Werner, Roland A.
    Sauer, Peter E.
    Gröcke, Darren R.
    Leuenberger, Markus C.
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Kahmen, Ansgar
    2H-fractionations during the biosynthesis of carbohydrates and lipids imprint a metabolic signal on the δ2H values of plant organic compounds2018In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, no 2, p. 479-491Article in journal (Refereed)
    Abstract [en]

    Hydrogen (H) isotope ratio (δ2H) analyses of plant organic compounds have been applied to assess ecohydrological processes in the environment despite a large part of the δ2H variability observed in plant compounds not being fully elucidated.

    We present a conceptual biochemical model based on empirical H isotope data that we generated in two complementary experiments that clarifies a large part of the unexplained variability in the δ2H values of plant organic compounds.

    The experiments demonstrate that information recorded in the δ2H values of plant organic compounds goes beyond hydrological signals and can also contain important information on the carbon and energy metabolism of plants. Our model explains where 2H‐fractionations occur in the biosynthesis of plant organic compounds and how these 2H‐fractionations are tightly coupled to a plant's carbon and energy metabolism. Our model also provides a mechanistic basis to introduce H isotopes in plant organic compounds as a new metabolic proxy for the carbon and energy metabolism of plants and ecosystems.

    Such a new metabolic proxy has the potential to be applied in a broad range of disciplines, including plant and ecosystem physiology, biogeochemistry and palaeoecology.

  • 2. Ehlers, Ina
    et al.
    Augusti, Angela
    Köhler, Iris
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Zuidema, Pieter
    Robertson, Iain
    Nilsson, Mats
    Marshall, John
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Detecting plant-climate interactions over decades-millennia using NMR isotopomer analysis2016In: Geophysical Research Abstracts, 2016, Vol. 18, article id EGU2016-9141-2Conference paper (Refereed)
  • 3.
    Ehlers, Ina
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Köhler, Iris
    Wieloch, Thomas
    Vlam, Mart
    van der Sleen, Peter
    Groenendijk, Peter
    Grabner, Michael
    Seim, Andrea
    Allen, Kathryn
    Wei, Liang
    Robertson, Iain
    Marshall, John
    Zuidema, Pieter A.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Limited suppression of photorespiration by 20th century atmospheric CO2 increase in trees worldwideManuscript (preprint) (Other academic)
    Abstract [en]

    Forests are a key component of the global carbon and hydrological cycle and forest responses to  environmental  drivers  create  important  feedbacks  to  these  cycles.  Photosynthetic efficiency of most forest tree species is strongly limited by photorespiration, a side reaction using O2 instead of CO2 as substrate, leading to a carbon loss for the plant. Photorespiration occurs in all trees and is reduced under elevated CO2 concentrations and increased under elevated temperature. Because the CO2 concentration of the atmosphere has increased in past decades, long-lived trees may have benefited from reduced photorespiration, but the temperature increase would have been a compensating detriment; but direct quantification of long-term changes in metabolic fluxes is lacking. Realistic forecasting of responses of trees and forests to future CO2 and temperature demands quantifying the reduction of photorespiration.  In  twelve  tree  species  from  five  continents,  we  observe  that photorespiration has been reduced by the CO2 increase during the past century, but for most the reduction is smaller than predicted from plant responses in CO2 alone. Comparison with data from a combined CO2 and temperature manipulation experiment shows that the reduced response can be explained by increases in leaf temperatures, which might result directly from increased  air  temperatures  or  indirectly  from  reduced  transpirative  cooling.  These  data suggest that global warming has already inhibited plant fertilization by increasing CO2, and that biomass increases may have been smaller than deduced from measurements of the heavy carbon isotope 13C. Observation of this centennial metabolic shift in tree physiology worldwide provides new insights into forest-climate feedbacks and can be used to improve coupled climate-vegetation models.

  • 4. Ehlers, Ina
    et al.
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Groenendijk, Peter
    Vlam, Mart
    van der Sleen, Peter
    Zuidema, Pieter A.
    Robertson, Iain
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Enhanced photosynthetic efficiency in trees world-wide by rising atmospheric CO2 levels2014In: Geophysical Research Abstracts, 2014, Vol. 16, article id EGU2014-12587-1Conference paper (Refereed)
  • 5. Laumer, W.
    et al.
    Andreu, L.
    Helle, G.
    Schleser, G. H.
    Wieloch, Thomas
    GeoForschungsZentrum Potsdam, Sektion 5.2, Klimadynamik und Landschaftsentwicklung, Telegrafenberg, Potsdam, Germany.
    Wissel, H.
    A novel approach for the homogenization of cellulose to use micro-amounts for stable isotope analyses2009In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 23, no 13, p. 1934-1940Article in journal (Refereed)
    Abstract [en]

    Climate reconstructions using stable isotopes from tree-rings are steadily increasing. The investigations concentrate mostly on cellulose due to its high stability. In recent years the available amount of cellulose has steadily decreased, mainly because micro-structures of plant material have had to be analyzed. Today, the amounts of cellulose being studied are frequently in the milligram and often in the microgram range. Consequently, homogeneity problems with regard to the stable isotopes of carbon and oxygen from cellulose have occurred and these have called for new methods in the preparation of cellulose for reliable isotope analyses. Three different methods were tested for preparing isotopically homogenous cellulose, namely mechanical grinding, freezing by liquid nitrogen with subsequent milling and ultrasonic breaking of cellulose fibres. The best precision of isotope data was achieved by freeze-milling and ultrasonic breaking. However, equipment for freeze-milling is expensive and the procedure is labour-intensive. Mechanical grinding resulted in a rather high loss of material and it is also labour-intensive. The use of ultrasound for breaking cellulose fibres proved to be the best method in terms of rapidity of sample throughput, avoidance of sample loss, precision of isotope results, ease of handling, and cost.

  • 6.
    Schleucher, Jürgen
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Serk, Henrik
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Immerzeel, Peter
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ehlers, Ina
    Nilsson, Mats
    Zuidema, Pieter
    Intramolecular stable isotope variation: Consequences for conventional isotope measurements and elucidation of new ecophysiological signals2018In: Geophysical Research Abstracts, 2018, Vol. 20, article id EGU2018-5511Conference paper (Refereed)
  • 7.
    Thomas, Wieloch
    et al.
    German Research Centre for Geosciences - GFZ, Section 5.2 Climate Dynamics and Landscape Evolution, Potsdam Dendro Laboratory, Telegrafenberg, Potsdam, Germany.
    Helle, G.
    Heinrich, I.
    Voigt, M.
    Schyma, P.
    A novel device for batch-wise isolation of a-cellulose from small-amount wholewood samples2011In: Dendrochronologia, ISSN 1125-7865, E-ISSN 1612-0051, Vol. 29, no 2, p. 115-117Article in journal (Refereed)
    Abstract [en]

    A novel device for the chemical isolation of α-cellulose from wholewood material of tree rings was designed by the Potsdam Dendro Laboratory. It allows the simultaneous treatment of up to several hundred micro samples. Key features are the batch-wise exchange of the chemical solutions, the reusability of all major parts and the easy and unambiguous labelling of each individual sample. Compared to classical methods labour intensity and running costs are significantly reduced.

  • 8.
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Our societies' wellbeing relies on stable and healthy environments. However, our current lifestyles, growth-oriented economic policies and the population explosion are leading to potentially catastrophic degradation of ecosystems and progressive disruption of food chains. Hopefully, more clarity about what the future holds in store will trigger stronger efforts to find, and adopt, problem-focused coping strategies and encourage environmentally friendly lifestyles.

    Forecasting environmental change/destruction is complicated (inter alia) by lack of complete understanding of plant-environment interactions, particularly those involved in slow processes such as plant acclimatisation and adaptation. This stems from deficiencies in tools to analyse such slow processes. The present work aims at developing tools that can provide retrospective ecophysiological information covering timescales from days to millennia.

    Natural archives, such as tree-rings, preserve plant metabolites over long timescales. Analyses of intramolecular isotope abundances in plant metabolites have the potential to provide retrospective information about metabolic processes and underlying environmental controls. Thus, my colleagues and I (hereafter we) analysed intramolecular isotope patterns in tree rings to develop analytical tools that can convey information about clearly-defined plant metabolic processes over multiple timescales. Such tools might help (inter alia) to constrain plants' capacities to sequester excess amounts of anthropogenic CO2; the so-called CO2 fertilisation effect. This, in turn, might shed light on plants' sink strength for the greenhouse gas CO2, and future plant performance and growth under climate change.

    In the first of three studies, reported in appended papers, we analysed intramolecular 13C/12C ratios in tree-ring glucose. In six angiosperm and six gymnosperm species we found pronounced intramolecular 13C/12C differences, exceeding 10‰. These differences are transmitted into major global C pools, such as soil organic matter. Taking intramolecular 13C/12C differences into account might improve isotopic characterisation of soil metabolic processes and soil CO2 effluxes. In addition, we analysed intramolecular 13C/12C ratios in a Pinus nigra tree-ring archive spanning the period 1961 to 1995. These data revealed new ecophysiological 13C/12C signals, which can facilitate climate reconstructions and assessments of plant-environment interactions at higher resolution; thus providing higher quality information. We proposed that 13C/12C signals at glucose C-1 to C-2 derive from carbon injection into the Calvin-Benson cycle via the oxidative pentose phosphate pathway. We concluded that intramolecular 13C/12C measurements provide valuable new information about long-term metabolic dynamics for application in biogeochemistry, plant physiology, plant breeding, and paleoclimatology.

    In the second study, we developed a comprehensive theory on the metabolic and ecophysiological origins of 13C/12C signals at tree-ring glucose C-5 and C-6. According to this theory and theoretical implications of the first study on signals at C-1 to C-3, analysis of such intramolecular signals can provide information about several metabolic processes. At C-3, a well-known signal reflecting CO2 uptake is preserved. The glucose-6-phosphate shunt around the Calvin-Benson cycle affects 13C/12C compositions at C-1 and C-2, while the 13C/12C signals at C-5 and C-6 reflect carbon fluxes into downstream metabolism. This theoretical framework enables further experimental studies to be conducted in a hypothesis-driven manner. In conclusion, the intramolecular approach provides information about carbon allocation in plant leaves. Thus, it gives access to long-term information on key ecophysiological processes, which could not be acquired by previous approaches.

    The abundance of the hydrogen isotope deuterium, δD, is important for linking the water cycle with plant ecophysiology. The main factors affecting δD in plant organic matter are commonly assumed to be the δD in source water and leaf-level evaporative enrichment. Current δD models incorporate biochemical D fractionations as constants. In the third study we showed that biochemical D fractionations respond strongly to low ambient CO2 levels and low light intensity. Thus, models of δD values in plant organic matter should incorporate biochemical fractionations as variables. In addition, we found pronounced leaf-level δD differences between α-cellulose and wax n-alkanes. We explained this by metabolite-specific contributions of distinct hydrogen sources during biosynthesis.

    Overall, this work advances our understanding of isotope distributions and isotope fractionations in plants. It reveals the immense potential of intramolecular isotope analyses for retrospective assessment of plant metabolism and associated environmental controls.

  • 9.
    Wieloch, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ehlers, Ina
    Frank, David
    Gessler, Arthur
    Grabner, Michael
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Tree-ring cellulose exhibits several distinct intramolecular 13C signals2017In: Geophysical Research Abstracts, 2017, Vol. 19, article id EGU2017-14723Conference paper (Refereed)
  • 10.
    Wieloch, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ehlers, Ina
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Frank, David
    Grabner, Michael
    Gessler, Arthur
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Intramolecular 13C analysis of tree rings provides multiple plant ecophysiology signals covering decades2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 5048Article in journal (Refereed)
    Abstract [en]

    Measurements of carbon isotope contents of plant organic matter provide important information in diverse fields such as plant breeding, ecophysiology, biogeochemistry and paleoclimatology. They are currently based on 13C/12C ratios of specific, whole metabolites, but we show here that intramolecular ratios provide higher resolution information. In the glucose units of tree-ring cellulose of 12 tree species, we detected large differences in 13C/12C ratios (>10‰) among carbon atoms, which provide isotopically distinct inputs to major global C pools, including wood and soil organic matter. Thus, considering position-specific differences can improve characterisation of soil-to-atmosphere carbon fluxes and soil metabolism. In a Pinus nigra tree-ring archive formed from 1961 to 1995, we found novel 13C signals, and show that intramolecular analysis enables more comprehensive and precise signal extraction from tree rings, and thus higher resolution reconstruction of plants’ responses to climate change. Moreover, we propose an ecophysiological mechanism for the introduction of a 13C signal, which links an environmental shift to the triggered metabolic shift and its intramolecular 13C signature. In conclusion, intramolecular 13C analyses can provide valuable new information about long-term metabolic dynamics for numerous applications.

  • 11.
    Wieloch, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Ehlers, Ina
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Frank, David
    Grabner, Michael
    Gessler, Arthur
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Tree-ring cellulose exhibits several interannual 13C signals on the intramolecular level2018In: Geophysical Research Abstracts, 2018, Vol. 20, article id EGU2018-17509-2Conference paper (Refereed)
    Abstract
  • 12.
    Wieloch, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Sharkey, Thomas David
    Werner, Roland Anton
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Intramolecular 13C/12C signals reflect carbon allocation in plant leavesManuscript (preprint) (Other academic)
1 - 12 of 12
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