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Department of Plant Biotechnology

Peer reviewed articles since 2000, descending

Friedrichs, N., Shokouhi, D., Heyer, A.G.: Flux Calculation for Primary Metabolism Reveals Changes in Allocation of Nitrogen to Different Amino Acid Families When Photorespiratory Activity Changes. International Journal of Molecular Sciences. 25, (2024). https://doi.org/10.3390/ijms25158394.
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@article{ijms25158394, abstract = {Photorespiration, caused by oxygenation of the enzyme Rubisco, is considered a wasteful process, because it reduces photosynthetic carbon gain, but it also supplies amino acids and is involved in amelioration of stress. Here, we show that a sudden increase in photorespiratory activity not only reduced carbon acquisition and production of sugars and starch, but also affected diurnal dynamics of amino acids not obviously involved in the process. Flux calculations based on diurnal metabolite profiles suggest that export of proline from leaves increases, while aspartate family members accumulate. An immense increase is observed for turnover in the cyclic reaction of glutamine synthetase/glutamine-oxoglutarate aminotransferase (GS/GOGAT), probably because of increased production of ammonium in photorespiration. The hpr1-1 mutant, defective in peroxisomal hydroxypyruvate reductase, shows substantial alterations in flux, leading to a shift from the oxoglutarate to the aspartate family of amino acids. This is coupled to a massive export of asparagine, which may serve in exchange for serine between shoot and root.}, article-number = {8394}, author = {Friedrichs, Nils and Shokouhi, Danial and Heyer, Arnd G.}, doi = {10.3390/ijms25158394}, issn = {1422-0067}, journal = {International Journal of Molecular Sciences}, number = 15, pubmedid = {39125964}, title = {Flux Calculation for Primary Metabolism Reveals Changes in Allocation of Nitrogen to Different Amino Acid Families When Photorespiratory Activity Changes}, url = {https://www.mdpi.com/1422-0067/25/15/8394}, volume = 25, year = 2024 }
Link
https://www.mdpi.com/1422-0067/25/15/8394
Kraemer, K., Kepp, G., Brock, J., Stutz, S., Heyer, A.G.: Acclimation to elevated CO2 affects the C/N balance by reducing de novo N-assimilation. Physiologia Plantarum. 174, e13615 (2022). https://doi.org/10.1111/ppl.13615.
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@article{noauthororeditor2021acclimation, author = {Kraemer, Konrad and Kepp, Gabi and Brock, Judith and Stutz, Simon and Heyer, Arnd G.}, doi = {10.1111/ppl.13615}, journal = {Physiologia Plantarum}, number = 1, pages = {e13615}, title = {Acclimation to elevated CO2 affects the C/N balance by reducing de novo N-assimilation}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/ppl.13615}, volume = 174, year = 2022 }
Link
https://onlinelibrary.wiley.com/doi/full/10.1111/ppl.13615
Kraemer, K., Brock, J., Heyer, A.G.: Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2. Frontiers in Plant Science. 13, (2022). https://doi.org/10.3389/fpls.2022.897924.
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@article{kraemer2022interaction, abstract = {It has been shown repeatedly that exposure to elevated atmospheric CO2 causes an increased C/N ratio of plant biomass that could result from either increased carbon or – in relation to C acquisition - reduced nitrogen assimilation. Possible reasons for diminished nitrogen assimilation are controversial, but an impact of reduced photorespiration at elevated CO2 has frequently been implied. Using a mutant defective in peroxisomal hydroxy-pyruvate reductase (hpr1-1) that is hampered in photorespiratory turnover, we show that indeed, photorespiration stimulates the glutamine-synthetase 2 (GS) / glutamine-oxoglutarate-aminotransferase (GOGAT) cycle, which channels ammonia into amino acid synthesis. However, mathematical flux simulations demonstrated that nitrate assimilation was not reduced at elevated CO2, pointing to a dilution of nitrogen containing compounds by assimilated carbon at elevated CO2. The massive growth reduction in the hpr1-1 mutant does not appear to result from nitrogen starvation. Model simulations yield evidence for a loss of cellular energy that is consumed in supporting high flux through the GS/GOGAT cycle that results from inefficient removal of photorespiratory intermediates. This causes a futile cycling of glycolate and hydroxy-pyruvate. In addition to that, accumulation of serine and glycine as well as carboxylates in the mutant creates a metabolic imbalance that could contribute to growth reduction.}, author = {Kraemer, Konrad and Brock, Judith and Heyer, Arnd G.}, doi = {10.3389/fpls.2022.897924}, journal = {Frontiers in Plant Science}, month = {07}, title = {Interaction of Nitrate Assimilation and Photorespiration at Elevated CO2}, url = {https://www.frontiersin.org/article/10.3389/fpls.2022.897924}, volume = 13, year = 2022 }
Link
https://www.frontiersin.org/article/10.3389/fpls.2022.897924
Hoermiller, I.I., Funck, D., Schönewolf, L., May, H., Heyer, A.G.: Cytosolic proline is required for basal freezing tolerance in Arabidopsis. Plant, Cell & Environment. (2022). https://doi.org/10.1111/pce.14196.
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@article{https://doi.org/10.1111/pce.14196, abstract = {Abstract The amino acid proline accumulates in many plant species under abiotic stress conditions, and various protective functions have been proposed. During cold stress, however, proline content in Arabidopsis thaliana does not correlate with freezing tolerance. Freezing sensitivity of a starchless plastidic phosphoglucomutase mutant (pgm) indicated that localization of proline in the cytosol might stabilize the plasma membrane during freeze–thaw events. Here, we show that re-allocation of proline from cytosol to vacuole was similar in the pyrroline-5-carboxylate synthase 2–1 (p5cs2–1) mutant and the pgm mutant, and caused similar reduction of basal freezing tolerance. In contrast, the starch excess 1–1 mutant (sex1-1) had even lower freezing tolerance than pgm, but did not affect sub-cellular localization of proline. Freezing sensitivity of sex1-1 mutants affected primarily the photosynthetic electron transport and was enhanced in a sex1-1::p5cs2–1 double mutant. These findings indicate that several independent factors determine basal freezing tolerance. In a pgm::p5cs2–1 double mutant, freezing sensitivity and proline allocation to the vacuole were the same as in the parental lines, indicating that the lack of cytosolic proline was the common cause of reduced basal freezing tolerance in both mutants. We conclude that cytosolic proline is an important factor in freezing tolerance of non-acclimated plants. This article is protected by copyright. All rights reserved.}, author = {Hoermiller, Imke I. and Funck, Dietmar and Schönewolf, Lilli and May, Henrik and Heyer, Arnd G.}, doi = {https://doi.org/10.1111/pce.14196}, eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/pce.14196}, journal = {Plant, Cell \& Environment}, title = {Cytosolic proline is required for basal freezing tolerance in Arabidopsis}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.14196}, year = 2022 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.14196
Roth-Nebelsick, A., Thiv, M., Malkowsky, Y., Schott, R., Heyer, A.: Structure and functional anatomy of the gas exchange apparatus of leafless orchids: evidence for a control mechanism? Botanical Journal of the Linnean Society. (2021). https://doi.org/10.1093/botlinnean/boab021.
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@article{rothnebelsick2021structure, abstract = {It is assumed that special structures in aerial roots of leafless orchids, aeration units, are involved in gas exchange regulation. In this study, the structure of aeration units in three leafless taxa (Microcoelia exilis, M. aphylla, Dendrophylax funalis) and a leaf-bearing species (Campylocentrum micranthum) are investigated to obtain more evidence of a possible mechanism for gas exchange control in aerial orchid roots. Extensive analyses of the anatomy of the velamen radicum, exodermis and cortex were performed using light and electron microscopy and µCT. In all considered leafless taxa, the aeration unit consists of pneumathodes (non-wettable regions in the velamen radicum), an exodermal aeration cell (EAC) with a thin cell wall (often equipped with a special internal layer showing a fluffy structure) and specialized cortical cells (SCC). The SCC provide gaps for gas exchange, show differentially thickened cell walls and are arranged in a staggered manner. Based on the 3D structure of the aeration unit, we suggest the possibility of dehydration-triggered gap closure (driven by root shrinkage), in the process of which first the SCC are pushed against each other and second the EAC are squeezed shut by the exodermis.}, author = {Roth-Nebelsick, Anita and Thiv, Mike and Malkowsky, Yaron and Schott, Rena and Heyer, Arnd}, doi = {10.1093/botlinnean/boab021}, journal = {Botanical Journal of the Linnean Society}, month = {03}, title = {Structure and functional anatomy of the gas exchange apparatus of leafless orchids: evidence for a control mechanism?}, url = {https://doi.org/10.1093/botlinnean/boab021}, year = 2021 }
Link
https://doi.org/10.1093/botlinnean/boab021
Krämer, K., Krämer, J., Heyer, A.: paropt: Parameter Optimizing of ODE-Systems. University of Stuttgart, University of Stuttgart, Institute of Biomaterials and Biomolecular Systems (2020).
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@manual{Kraemer2020, address = {University of Stuttgart, Institute of Biomaterials and Biomolecular Systems}, author = {Krämer, Konrad and Krämer, Johannes and Heyer, Arnd}, month = {07}, note = {R package version 0.1}, organization = {University of Stuttgart}, title = {paropt: Parameter Optimizing of ODE-Systems}, url = {https://CRAN.R-project.org/package=paropt}, year = 2020 }
Link
https://CRAN.R-project.org/package=paropt
Helisch, H., Keppler, J., Detrell, G., Belz, S., Ewald, R., Fasoulas, S., Heyer, A.G.: High density long-term cultivation of Chlorella vulgaris SAG 211-12 in a novel microgravity-capable membrane raceway photobioreactor for future bioregenerative life support in SPACE. Life Sciences in Space Research. 24, 91–107 (2020). https://doi.org/10.1016/j.lssr.2019.08.001.
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@article{noauthororeditor, abstract = {Hybrid life support systems are of great interest for future far-distant space exploration missions to planetary surfaces, e.g. Mars, planned until 2050. By synergistically combining physicochemical and biotechnological algae-based subsystems, an essential step towards the closure of the carbon loop in environmental control and life support systems (ECLSS) shall be accomplished, offering a wide beneficial potential for ECLSS through the utilization of oxygenic photosynthesis: O2 and potential human food can be formed in-situ from CO2 and water. The wild type green alga Chlorella vulgaris strain SAG 211-12 was selected as model microorganism due to its photoautotrophic growth, high biomass yield, cultivation flexibility and long-term cultivation robustness. The current study presents for the first time a stable xenic long-term processing of microalgae in a novel microgravity capable membrane raceway photobioreactor for 188 days with the focus on algal growth kinetics and gas evolution. In particular, culture homogeneity and viability were monitored and evaluated during the whole cultivation process due to their putative crucial impact on long-term functionality and efficiency of a closed cultivation system. Based on a specially designed cyclic batch cultivation process for SAG 211-12, a successive biomass growth up to a maximum of 12.2 g l−1 with a max. global volumetric productivity of 1.3 g l−1 d−1 was reached within the closed loop system. The photosynthetic capacity was assessed to a global molar photo- synthetic quotient of 0.31. Furthermore, cultivation parameters for a change from batch to continuous processing at high biomass densities and proliferation rates are introduced. The presented μgPBR miniature plant and the developed high throughput cultivation process are planned to be tested under real space conditions within the PBR@LSR project (microgravity and cosmic radiation) aboard the International Space Station with an operation period of up to 180 days to investigate the impact on long-term system stability.}, author = {Helisch, Harald and Keppler, Jochen and Detrell, Gisela and Belz, Stefan and Ewald, Reinhold and Fasoulas, Stefanos and Heyer, Arnd G.}, doi = {10.1016/j.lssr.2019.08.001}, journal = {Life Sciences in Space Research}, language = {https://doi.org/10.1016/j.lssr.2019.08.001}, month = {01}, pages = {91-107}, title = {High density long-term cultivation of Chlorella vulgaris SAG 211-12 in a novel microgravity-capable membrane raceway photobioreactor for future bioregenerative life support in SPACE}, volume = 24, year = 2020 }
Küstner, L., Nägele, T., Heyer, A.G.: Mathematical modeling of diurnal patterns of carbon allocation to shoot and root in Arabidopsis thaliana. npj Systems Biology and Applications. 5, 4-- (2019). https://doi.org/10.1038/s41540-018-0080-1.
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@article{kustner2019, abstract = {We developed a mathematical model to simulate dynamics of central carbon metabolism over complete diurnal cycles for leaves of Arabidopsis thaliana exposed to either normal (120 µmol m−2 s−1) or high light intensities (1200 µmol m−2 s−1). The main objective was to obtain a high-resolution time series for metabolite dynamics as well as for shoot structural carbon formation (compounds with long residence time) and assimilate export of aerial organs to the sink tissue. Model development comprised a stepwise increment of complexity to finally approach the in vivo situation. The correct allocation of assimilates to either sink export or shoot structural carbon formation was a central goal of model development. Diurnal gain of structural carbon was calculated based on the daily increment in total photosynthetic carbon fixation, and this was the only parameter for structural carbon formation implemented in the model. Simulations of the dynamics of central metabolite pools revealed that shoot structural carbon formation occurred solely during the light phase but not during the night. The model allowed simulation of shoot structural carbon formation as a function of central leaf carbon metabolism under different environmental conditions without structural modifications. Model simulations were performed for the accession Landsberg erecta (Ler) and its hexokinase null-mutant gin2-1. This mutant displays a slow growth phenotype especially at increasing light intensities. Comparison of simulations revealed that the retarded shoot growth in the mutant resulted from an increased assimilate transport to sink organs. Due to its central function in sucrose cycling and sugar signaling, our findings suggest an important role of hexokinase-1 for carbon allocation to either shoot growth or assimilate export.}, author = {Küstner, Lisa and Nägele, Thomas and Heyer, Arnd G.}, doi = {10.1038/s41540-018-0080-1}, issn = {20567189}, journal = {npj Systems Biology and Applications}, number = 1, pages = {4--}, refid = {Küstner2019}, title = {Mathematical modeling of diurnal patterns of carbon allocation to shoot and root in Arabidopsis thaliana}, url = {https://doi.org/10.1038/s41540-018-0080-1}, volume = 5, year = 2019 }
Link
https://doi.org/10.1038/s41540-018-0080-1
Küstner, L., Fürtauer, L., Weckwerth, W., Nägele, T., Heyer, A.G.: Subcellular dynamics of proteins and metabolites under abiotic stress reveal deferred response of the Arabidopsis thaliana hexokinase‐1 mutant gin2‐1 to high light. Plant Journal. 100, 456–472 (2019). https://doi.org/10.1111/tpj.14491.
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@article{kustner2019subcellular, abstract = {Stress responses in plants imply spatio‐temporal changes in enzymes and metabolites, including subcellular compartment‐specific reallocation processes triggered by sudden changes in environmental parameters. To investigate interactions of primary metabolism with abiotic stress, the gin2‐1 mutant, defective in the sugar sensor hexokinase 1 (HXK1) was compared to its wildtype Landsberg erecta (Ler) based on time resolved, compartment specific metabolome and proteome data obtained over a full diurnal cycle. The high light sensitive gin2‐1 mutant was substantially delayed in subcellular redistribution of metabolites upon stress, and this correlated with a massive reduction in proteins belonging to the ATP producing electron transport chain under high light, while fewer changes occurred in the cold. In the wildtype, compounds specifically protecting individual compartments could be identified, e.g. maltose and raffinose in plastids, myo‐inositol in mitochondria, but gin2‐1 failed to recruit these substances to the respective compartments, or responded only slowly to high irradiance. No such delay was obtained in the cold. At the whole‐cell level, concentrations of the amino acids, glycine and serine, provided strong evidence for an important role of the photorespiratory pathway during stress exposure, and different subcellular allocation of serine may contribute to the slow growth of the gin2‐1 mutant under high irradiance.}, author = {Küstner, Lisa and Fürtauer, Lisa and Weckwerth, Wolfram and Nägele, Thomas and Heyer, Arnd G.}, doi = {10.1111/tpj.14491}, journal = {Plant Journal}, month = {08}, pages = {456-472}, title = {Subcellular dynamics of proteins and metabolites under abiotic stress reveal deferred response of the Arabidopsis thaliana hexokinase‐1 mutant gin2‐1 to high light}, url = {https://doi.org/10.1111/tpj.14491}, volume = 100, year = 2019 }
Link
https://doi.org/10.1111/tpj.14491
Hell, A.F., Kretzschmar, F.S., Simões, K., Heyer, A.G., Barbedo, C.J., Braga, M.R., Centeno, D.C.: Metabolic Changes on the Acquisition of Desiccation Tolerance in Seeds of the Brazilian Native Tree Erythrina speciosa. Frontiers in Plant Science. 10, 1356 (2019). https://doi.org/10.3389/fpls.2019.01356.
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@article{hell2019metabolic, abstract = {Erythrina speciosa Andrews (Fabaceae) is a native tree of Atlantic forest from Southern and Southeastern Brazil. Although this species is found in flooded areas, it produces highly desiccation tolerant seeds. Here, we investigated the physiological and metabolic events occurring during seed maturation of E. speciosa aiming to better understand of its desiccation tolerance acquisition. Seeds were separated into six stages of maturation by the pigmentation of the seed coat. Water potential (WP) and water content (WC) decreased gradually from the first stage to the last stage of maturation (VI), in which seeds reached the highest accumulation of dry mass and seed coat acquired water impermeability. At stage III (71% WC), although seeds were intolerant to desiccation, they were able to germinate (about 15%). Desiccation tolerance was first observed at stage IV (67% WC), in which 40% of seeds were tolerant. At stage V (24% WC), all seeds were tolerant to desiccation and at stage VI all seeds germinated. Increased deposition of the arabinose-containing polysaccharides, which are known as cell wall plasticizers polymers, was observed up to stage IV of seed maturation. Raffinose and stachyose gradually increased in axes and cotyledons with greater increment in the fourth stage. Metabolic profile analysis showed that levels of sugars, organic, and amino acids decrease drastically in embryonic axes, in agreement with lower respiratory rates during maturation. Moreover, a non-aqueous fractionation revealed a change on the proportions of sugar accumulation among cytosol, plastid, and vacuoles between the active metabolism (stage I) and the dormant seeds (stage VI). The results indicate that the physiological maturity of the seeds of E. speciosa is reached at stage V and that the accumulation of raffinose can be a result of the change in the use of carbon, reducing metabolic activity during maturation. This work confirms that raffinose is involved in desiccation tolerance in seeds of E. speciosa, especially considering the different subcellular compartments and suggests even that the acquisition of desiccation tolerance in this species occurs in stages prior to the major changes in WC.}, author = {Hell, Aline F. and Kretzschmar, Fernanda S. and Simões, Kelly and Heyer, Arnd G. and Barbedo, Claudio J. and Braga, Marcia R. and Centeno, Danilo C.}, doi = {10.3389/fpls.2019.01356}, issn = {1664-462X}, journal = {Frontiers in Plant Science}, language = {English}, month = {10}, pages = 1356, title = {Metabolic Changes on the Acquisition of Desiccation Tolerance in Seeds of the Brazilian Native Tree Erythrina speciosa}, url = {https://doi.org/10.3389/fpls.2019.01356}, volume = 10, year = 2019 }
Link
https://doi.org/10.3389/fpls.2019.01356
Fürtauer, L., Küstner, L., Weckwerth, W., Heyer, A.G., Nägele, T.: Resolving subcellular plant metabolism. Plant Journal. 100, 438–455 (2019). https://doi.org/10.1111/tpj.14472.
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@article{furtauer2019resolving, abstract = {Plant cells are characterized by a high degree of compartmentalization and a diverse proteome and metabolome. Only a very limited number of studies has addressed combined subcellular proteomics and metabolomics which strongly limits biochemical and physiological interpretation of large‐scale omics data. Our study presents a methodological combination of non‐aqueous fractionation, shotgun proteomics, enzyme activities and metabolomics to reveal subcellular diurnal dynamics of plant metabolism. Subcellular marker protein sets were identified and enzymatically validated to resolve metabolism in a 4‐compartment model comprising chloroplasts, cytosol, vacuole and mitochondria. These marker sets are now available for future studies which aim to monitor subcellular metabolome and proteome dynamics. Comparing subcellular dynamics in wild type plants and HXK1‐deficient gin2‐1 mutants revealed a strong impact of HXK1 activity on metabolome dynamics in multiple compartments. Glucose accumulation in the cytosol of gin2‐1 was accompanied by diminished vacuolar glucose levels. Subcellular dynamics of pyruvate, succinate and fumarate amount was significantly affected in gin2‐1 which coincided with differential mitochondrial proteome dynamics. Lowered mitochondrial glycine and serine amount in gin2‐1 together with reduced abundance of photorespiratory proteins indicated an effect of the gin2‐1 mutation on photorespiratory capacity. Our findings highlight the necessity to resolve plant metabolism to a subcellular level in order to provide a causal relationship between metabolites, proteins and metabolic pathway regulation.}, author = {Fürtauer, Lisa and Küstner, Lisa and Weckwerth, Wolfram and Heyer, Arnd G. and Nägele, Thomas}, doi = {10.1111/tpj.14472}, journal = {Plant Journal}, month = {07}, pages = {438-455}, title = {Resolving subcellular plant metabolism}, url = {https://doi.org/10.1111/tpj.14472}, volume = 100, year = 2019 }
Link
https://doi.org/10.1111/tpj.14472
Mishra, K.B., Mishra, A., Kubásek, J., Urban, O., Heyer, A.G., Govindjee: Low temperature induced modulation of photosynthetic induction in non-acclimated and cold-acclimated Arabidopsis thaliana: chlorophyll a fluorescence and gas-exchange measurements. Photosynthesis Research. (2018). https://doi.org/10.1007/s11120-018-0588-7.
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@article{Mishra2018, abstract = {Cold acclimation modifies the photosynthetic machinery and enables plants to survive at sub-zero temperatures, whereas in warm habitats, many species suffer even at non-freezing temperatures. We have measured chlorophyll a fluorescence (ChlF) and CO2 assimilation to investigate the effects of cold acclimation, and of low temperatures, on a cold-sensitive Arabidopsis thaliana accession C24. Upon excitation with low intensity (40 {\textmu}mol photons m−{\thinspace}2 s−{\thinspace}1){\thinspace}{\textasciitilde}{\thinspace}620 nm light, slow (minute range) ChlF transients, at {\textasciitilde}{\thinspace}22 {\textdegree}C, showed two waves in the SMT phase (S, semi steady-state; M, maximum; T, terminal steady-state), whereas CO2 assimilation showed a linear increase with time. Low-temperature treatment (down to −{\thinspace}1.5 {\textdegree}C) strongly modulated the SMT phase and stimulated a peak in the CO2 assimilation induction curve. We show that the SMT phase, at {\textasciitilde}{\thinspace}22 {\textdegree}C, was abolished when measured under high actinic irradiance, or when 3-(3, 4-dichlorophenyl)-1, 1- dimethylurea (DCMU, an inhibitor of electron flow) or methyl viologen (MV, a Photosystem I (PSI) electron acceptor) was added to the system. Our data suggest that stimulation of the SMT wave, at low temperatures, has multiple reasons, which may include changes in both photochemical and biochemical reactions leading to modulations in non-photochemical quenching (NPQ) of the excited state of Chl, ``state transitions,'' as well as changes in the rate of cyclic electron flow through PSI. Further, we suggest that cold acclimation, in accession C24, promotes ``state transition'' and protects photosystems by preventing high excitation pressure during low-temperature exposure.}, author = {Mishra, Kumud B. and Mishra, Anamika and Kub{\'a}sek, Ji{\v{r}}{\'i} and Urban, Otmar and Heyer, Arnd G. and Govindjee}, day = 10, doi = {10.1007/s11120-018-0588-7}, issn = {1573-5079}, journal = {Photosynthesis Research}, month = {10}, title = {Low temperature induced modulation of photosynthetic induction in non-acclimated and cold-acclimated Arabidopsis thaliana: chlorophyll a fluorescence and gas-exchange measurements}, url = {https://doi.org/10.1007/s11120-018-0588-7}, year = 2018 }
Link
https://doi.org/10.1007/s11120-018-0588-7
Hoermiller, I.I., Ruschhaupt, M., Heyer, A.G.: Mechanisms of frost resistance in Arabidopsis thaliana. Planta. 248, 827–835 (2018). https://doi.org/10.1007/s00425-018-2939-1.
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@article{Hoermiller2018, abstract = {Freezing resistance strategies vary in Arabidopsis depending on origin. Southern accessions may avoid or tolerate freezing, while northern ones are always tolerant and reduce the proportion of freezable tissue water during acclimation.}, author = {Hoermiller, Imke I. and Ruschhaupt, Moritz and Heyer, Arnd G.}, day = 01, doi = {10.1007/s00425-018-2939-1}, issn = {1432-2048}, journal = {Planta}, month = {10}, number = 4, pages = {827-835}, title = {Mechanisms of frost resistance in Arabidopsis thaliana}, url = {https://doi.org/10.1007/s00425-018-2939-1}, volume = 248, year = 2018 }
Link
https://doi.org/10.1007/s00425-018-2939-1
Brauner, K., Birami, B., Brauner, H.A., Heyer, A.G.: Diurnal periodicity of assimilate transport shapes resource allocation and whole-plant carbon balance. The Plant Journal. 94, 776–789 (2018). https://doi.org/10.1111/tpj.13898.
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@article{doi:10.1111/tpj.13898, abstract = {Summary Whole-plant carbon balance comprises diurnal fluctuations of photosynthetic carbon gain and respiratory losses, as well as partitioning of assimilates between phototrophic and heterotrophic organs. Because it is difficult to access, the root system is frequently neglected in growth models, or its metabolism is rated based on generalizations from other organs. Here, whole-plant cuvettes were used for investigating total-plant carbon exchange with the environment over full diurnal cycles. Dynamics of primary metabolism and diurnally resolved phloem exudation profiles, as proxy of assimilate transport, were combined to obtain a full picture of resource allocation. This uncovered a strong impact of periodicity of inter-organ transport on the efficiency of carbon gain. While a sinusoidal fluctuation of the transport rate, with minor diel deflections, minimized respiratory losses in Arabidopsis wild-type plants, triangular or rectangular patterns of transport, found in mutants defective in either starch or sucrose metabolism, increased root respiration at the end or beginning of the day, respectively. Power spectral density and cross-correlation analysis revealed that only the rate of starch synthesis was strictly correlated to the rate of net photosynthesis in wild-type, while in a sucrose-phosphate synthase mutant (spsa1), this applied also to carboxylate synthesis, serving as an alternative carbon pool. In the starchless mutant of plastidial phospho-gluco mutase (pgm), none of these rates, but concentrations of sucrose and glucose in the root, followed the pattern of photosynthesis, indicating direct transduction of shoot sugar levels to the root. The results demonstrate that starch metabolism alone is insufficient to buffer diurnal fluctuations of carbon exchange.}, author = {Brauner, Katrin and Birami, Benjamin and Brauner, Horst A. and Heyer, Arnd G.}, doi = {10.1111/tpj.13898}, eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.13898}, journal = {The Plant Journal}, number = 5, pages = {776-789}, title = {Diurnal periodicity of assimilate transport shapes resource allocation and whole-plant carbon balance}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/tpj.13898}, volume = 94, year = 2018 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/tpj.13898
Birami, B., Gattmann, M., Heyer, A.G., Grote, R., Arneth, A., Ruehr, N.: Heat waves alter carbon allocation and increase mortality of Aleppo pine under dry conditions. Frontiers in Forests and Global Change. 1, 8 (2018). https://doi.org/doi: 10.3389/ffgc.2018.00008.
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@article{birami2018waves, abstract = {Climate extremes are likely to occur more frequently in the future, including a combination of heat waves and drought. However, the responses of trees to combined stress and their post-stress recovery are not fully understood yet. Therefore, this study investigates the responses of semi-arid Pinus halepensis seedlings to moderate drought, heat and combined heat-drought stress, as well as post-stress recovery. The seedlings were grown under controlled conditions and exposed to two 4-day-long heat periods, reaching air temperature maxima of 42 °C and vapor pressure deficit (VPD) of 7 kPa. Day- and nighttime canopy gas exchange was measured and differences in shoot and root allocation of non-structural carbohydrate (NSC) compounds (soluble sugars, starch, cyclitols and carboxylic acids) assessed. Fluorescence parameters, nitrate levels, proline content and shoot water potential (ψ) provided additional indicators for stress severity and recovery performance. During the heat periods, net photosynthesis and stomatal conductance decrease immediately. This decline was modest under well-watered conditions, with transpiration and dark respiration rates remaining high and despite reductions in root NSC content, trees recovered following heat release. This was not the case in the heat-drought treatment, where stress resulted in mortality was high and the few surviving seedlings showed reduced gas exchange rates and low root NSC content, while leaf nitrate and proline remained elevated even three weeks after heat release. Shoot ψ indicated that hydraulic failure was not the reason for mortality in the heat-drought exposed seedlings. Instead, we hypothesize that low transpiration rates, which resulted in needle temperatures >47 °C during heat stress (6 °C above air temperature) have led to irreversible damage. In summary, it could be demonstrated that heat waves in combination with moderate drought can either result in increased mortality or, if the seedlings survive, in delayed recovery. This highlights the potential of an increase in heat wave temperatures to trigger forest decline in semi-arid regions.}, author = {Birami, Benjamin and Gattmann, Marielle and Heyer, Arnd G. and Grote, Rüdiger and Arneth, Almut and Ruehr, Nadine}, day = 27, doi = {doi: 10.3389/ffgc.2018.00008}, journal = {Frontiers in Forests and Global Change}, month = {11}, pages = 8, title = {Heat waves alter carbon allocation and increase mortality of Aleppo pine under dry conditions}, url = {https://www.frontiersin.org/articles/10.3389/ffgc.2018.00008/abstract}, volume = 1, year = 2018 }
Link
https://www.frontiersin.org/articles/10.3389/ffgc.2018.00008/abstract
Hoermiller, I.I., Naegele, T., Augustin, H., Stutz, S., Weckwerth, W., Heyer, A.G.: Subcellular reprogramming of metabolism during cold acclimation in Arabidopsis thaliana. Plant Cell Environ. 40, 602–610 (2017). https://doi.org/10.1111/pce.12836.
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@article{Hoermiller2017, abstract = {Abstract Metabolite changes in plant leaves during exposure to low temperatures involve re‐allocation of a large number of metabolites between sub‐cellular compartments. Therefore, metabolite determination at the whole cell level may be insufficient for interpretation of the functional significance of cellular compounds. To investigate the cold‐induced metabolite dynamics at the level of individual sub‐cellular compartments, an integrative platform was developed that combines quantitative metabolite profiling by gas chromatography coupled to mass spectrometry (GC‐MS) with the non‐aqueous fractionation technique allowing separation of cytosol, vacuole and the plastidial compartment. Two mutants of Arabidopsis thaliana representing antipodes in the diversion of carbohydrate metabolism between sucrose and starch were compared to Col‐0 wildtype before and after cold acclimation to investigate interactions of cold acclimation with subcellular re‐programming of metabolism. A multivariate analysis of the data set revealed dominant effects of compartmentation on metabolite concentrations that were modulated by environmental condition and genetic determinants. While for both, the starchless mutant of plastidial phospho‐gluco mutase (pgm) and a mutant defective in sucrose‐phosphate synthase A1, metabolic constraints, especially at low temperature, could be uncovered based on subcellularly resolved metabolite profiles, only pgm had lowered freezing tolerance. Metabolic profiles of pgm point to redox imbalance as a possible reason for reduced cold acclimation capacity.}, author = {Hoermiller, Imke I. and Naegele, Thomas and Augustin, Hanna and Stutz, Simon and Weckwerth, Wolfram and Heyer, Arnd G.}, doi = {10.1111/pce.12836}, eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/pce.12836}, journal = {Plant Cell Environ.}, number = 5, pages = {602-610}, title = {Subcellular reprogramming of metabolism during cold acclimation in Arabidopsis thaliana}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.12836}, volume = 40, year = 2017 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.12836
Xu, E., Vaathera, L., Hörak, H., Hincha, D.K., Heyer, A.G., Brosche, M.: Quantitative trait loci mapping and transcriptome analysis reveal candidate genes regulating the response to ozone in Arabidopsis thaliana. Plant, Cell & Environment. 38, 1418–1433 (2015). https://doi.org/10.1111/pce.12499.
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@article{10.1111/pce.12499, abstract = {Abstract As multifaceted molecules, reactive oxygen species (ROS) are known to accumulate in response to various stresses. Ozone (O3) is an air pollutant with detrimental effect on plants and O3 can also be used as a tool to study the role of ROS in signalling. Genetic variation of O3 sensitivity in different Arabidopsis accessions highlights the complex genetic architecture of plant responses to ROS. To investigate the genetic basis of O3 sensitivity, a recombinant inbred line (RIL) population between two Arabidopsis accessions with distinct O3 sensitivity, C24 (O3 tolerant) and Te (O3 sensitive) was used for quantitative trait loci (QTL) mapping. Through analysis of QTL mapping combined with transcriptome changes in response to O3, we identified three causal QTLs and several potential candidate genes regulating the response to O3. Based on gene expression data, water loss and stomatal conductance measurement, we found that a combination of relatively low stomatal conductance and constitutive activation of salicylic acid (SA)-mediated defence signalling were responsible for the O3 tolerance in C24. Application of exogenous SA prior to O3 exposure can mimic the constitutive SA signalling in C24 and could attenuate O3-induced leaf damage in the sensitive Arabidopsis accessions Te and Cvi-0.}, author = {Xu, Enjun and Vaathera, Lauri and Hörak, Hanna and Hincha, Dirk K. and Heyer, Arnd G. and Brosche, Mikael}, doi = {10.1111/pce.12499}, eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/pce.12499}, journal = {Plant, Cell \& Environment}, number = 7, pages = {1418-1433}, title = {Quantitative trait loci mapping and transcriptome analysis reveal candidate genes regulating the response to ozone in Arabidopsis thaliana}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.12499}, volume = 38, year = 2015 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.12499
Nissen, M., Shcherbakov, D., Heyer, A., Brümmer, F., Schill, R.O.: Behaviour of the plathelminth Symsagittifera roscoffensis under different light conditions and the consequences for the symbiotic algae Tetraselmis convolutae. Journal of Experimental Biology. 218, 1693--1698 (2015). https://doi.org/10.1242/jeb.110429.
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@article{Nissen1693, abstract = {Symsagittifera roscoffensis is a plathelminth living in symbiosis with the green algae Tetraselmis convolutae. Host and symbiont are a model system for the study of endosymbiosis, which has so far mainly focused on their biochemical interactions. Symsagittifera roscoffensis is well known for its positive phototaxis that is hypothesized to optimize the symbiont{\textquoteright}s light perception for photosynthesis. In this study, we conducted a detailed analysis of phototaxis using light sources of different wavelength and brightness by videotracking. Furthermore, we compared the behavioural data with the electron transfer rate of the photosystem from cultured symbiotic cells. The symbiotic algae is adapted to low light conditions, showing a positive electron transfer rate at a photosynthetically active radiation of 0.112 {\textmu}mol photons~m-2~s-1, and S. roscoffensis showed a positive phototactic behaviour for light intensities up to 459.17 {\textmu}mol photons~m-2~s-1, which is not optimal regarding the needs of the symbiotic cells and may even harm host and symbiont. Red light cannot be detected by the animals and therefore their eyes seem not to be suitable for measuring the exact photosynthetically active radiation to the benefit of the photosymbionts.}, author = {Nissen, Matthias and Shcherbakov, Denis and Heyer, Arnd and Br{\"u}mmer, Franz and Schill, Ralph O.}, doi = {10.1242/jeb.110429}, eprint = {http://jeb.biologists.org/content/218/11/1693.full.pdf}, issn = {0022-0949}, journal = {Journal of Experimental Biology}, number = 11, pages = {1693--1698}, publisher = {The Company of Biologists Ltd}, title = {Behaviour of the plathelminth Symsagittifera roscoffensis under different light conditions and the consequences for the symbiotic algae Tetraselmis convolutae}, url = {http://jeb.biologists.org/content/218/11/1693}, volume = 218, year = 2015 }
Link
http://jeb.biologists.org/content/218/11/1693
Brauner, K., Stutz, S., Paul, M., Heyer, A.G.: Measuring whole plant CO2 exchange with the environment reveals opposing effects of the gin2–1 mutation in shoots and roots of Arabidopsis thaliana. Plant Signaling Behav. 10, e973822 (2015). https://doi.org/10.4161/15592324.2014.973822.
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@article{Brauner2015, abstract = { Using a cuvette for simultaneous measurement of net photosynthesis in above ground plant organs and root respiration we investigated the effect of reduced leaf glucokinase activity on plant carbon balance. The gin2–1 mutant of Arabidopsis thaliana is characterized by a 50\% reduction of glucokinase activity in the shoot, while activity in roots is about fivefold higher and similar to wild type plants. High levels of sucrose accumulating in leaves during the light period correlated with elevated root respiration in gin2–1. Despite substantial respiratory losses in roots, growth retardation was moderate, probably because photosynthetic carbon fixation was simultaneously elevated in gin2–1. Our data indicate that futile cycling of sucrose in shoots exerts a reduction on net CO2 gain, but this is over-compensated by the prevention of exaggerated root respiration resulting from high sucrose concentration in leaf tissue. }, author = {Brauner, Katrin and Stutz, Simon and Paul, Martin and Heyer, Arnd G}, doi = {10.4161/15592324.2014.973822}, eprint = {http://dx.doi.org/10.4161/15592324.2014.973822}, journal = {Plant Signaling Behav.}, note = {PMID: 25482780}, number = 1, pages = {e973822}, title = {Measuring whole plant CO2 exchange with the environment reveals opposing effects of the gin2–1 mutation in shoots and roots of Arabidopsis thaliana}, url = {http://dx.doi.org/10.4161/15592324.2014.973822 }, volume = 10, year = 2015 }
Link
http://dx.doi.org/10.4161/15592324.2014.973822
Mishra, A., Heyer, A., Mishra, K.: Chlorophyll fluorescence emission can screen cold tolerance of cold acclimated Arabidopsis thaliana accessions. Plant Methods. 10, 38 (2014). https://doi.org/10.1186/1746-4811-10-38.
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@article{Mishra2014, abstract = {BACKGROUND:An easy and non-invasive method for measuring plant cold tolerance is highly valuable to instigate research targeting breeding of cold tolerant crops. Traditional methods are labor intensive, time-consuming and thereby of limited value for large scale screening. Here, we have tested the capacity of chlorophyll a fluorescence (ChlF) imaging based methods for the first time on intact whole plants and employed advanced statistical classifiers and feature selection rules for finding combinations of images able to discriminate cold tolerant and cold sensitive plants.RESULTS:ChlF emission from intact whole plant rosettes of nine Arabidopsis thaliana accessions was measured for (1) non-acclimated (NAC, six week old plants grown at room temperature), (2) cold acclimated (AC, NAC plants acclimated at 4degreesC for two weeks), and (3) sub-zero temperature (ST) treated (STT, AC plants treated at -4degreesC for 8h in dark) states. Cold acclimation broadened the slow phase of ChlF transients in cold sensitive (Co, C24, Can and Cvi) A. thaliana accessions. Similar broadening in the slow phase of ChlF transients was observed in cold tolerant (Col, Rsch, and Te) plants following ST treatments. ChlF parameters: maximum quantum yield of PSII photochemistry (FV/FM) and fluorescence decrease ratio (RFD) well categorized the cold sensitive and tolerant plants when measured in STT state. We trained a range of statistical classifiers with the sequence of captured ChlF images and selected a high performing quadratic discriminant classifier (QDC) in combination with sequential forward floating selection (SFFS) feature selection methods and found that linear combination of three images showed a reasonable contrast between cold sensitive and tolerant A. thaliana accessions for AC as well as for STT states.CONCLUSIONS:ChlF transients measured for an intact whole plant is important for understanding the impact of cold acclimation on photosynthetic processes. Combinatorial imaging combined with statistical classifiers and feature selection methods worked well for the screening of cold tolerance without exposing plants to sub-zero temperatures. This opens up new possibilities for high-throughput monitoring of whole plants cold tolerance via easy and fully non-invasive means.}, author = {Mishra, Anamika and Heyer, Arnd and Mishra, Kumud}, doi = {10.1186/1746-4811-10-38}, issn = {1746-4811}, journal = {Plant Methods}, number = 1, pages = 38, pubmedid = {25400689}, title = {Chlorophyll fluorescence emission can screen cold tolerance of cold acclimated \textit{Arabidopsis thaliana} accessions}, url = {http://www.plantmethods.com/content/10/1/38}, volume = 10, year = 2014 }
Link
http://www.plantmethods.com/content/10/1/38
Do, P.T., Drechsel, O., Heyer, A.G., Hincha, D.K., Zuther, E.: Changes in free polyamine levels, expression of polyamine biosynthesis genes, and performance of rice cultivars under salt stress: a comparison with responses to drought. Frontiers in Plant Science. 5, (2014). https://doi.org/10.3389/fpls.2014.00182.
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@article{Do_2014, author = {Do, Phuc T. and Drechsel, Oliver and Heyer, Arnd G. and Hincha, Dirk K. and Zuther, Ellen}, doi = {10.3389/fpls.2014.00182}, journal = {Frontiers in Plant Science}, month = {05}, publisher = {Frontiers Media {SA}}, title = {Changes in free polyamine levels, expression of polyamine biosynthesis genes, and performance of rice cultivars under salt stress: a comparison with responses to drought}, url = {https://doi.org/10.3389%2Ffpls.2014.00182}, volume = 5, year = 2014 }
Link
https://doi.org/10.3389%2Ffpls.2014.00182
Brauner, K., Hörmiller, I., Nägele, T., Heyer, A.G.: Exaggerated root respiration accounts for growth retardation in a starchless mutant of Arabidopsis thaliana. Plant J. 79, 82--91 (2014). https://doi.org/10.1111/tpj.12555.
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@article{Brauner2014, abstract = {The knock-out mutation of plastidial phosphoglucomutase (pgm) causes a starchless phenotype in Arabidopsis thaliana, and results in a severe growth reduction of plants cultivated under diurnal conditions. It has been speculated that high soluble sugar levels accumulating during the light phase in leaf mesophyll might cause a reduction of photosynthetic activity or that shortage of reduced carbon during the night is the reason for the slow biomass gain of pgm. Separate simultaneous measurements of leaf net photosynthesis and root respiration demonstrate that photosynthetic activity per unit fresh weight is not reduced in pgm, whereas root respiration is strongly elevated. Comparison with a mutant defective in the dominating vacuolar invertase (AtβFruct4) revealed that high sucrose concentration in the cytosol, but not in the vacuole, of leaf cells is responsible for elevated assimilate transport to the root. Increased sugar supply to the root, as observed in pgm mutants, forces substantial respiratory losses. Because root respiration accounts for 80% of total plant respiration under long-day conditions, this gives rise to retarded biomass formation. In contrast, reduced vacuolar invertase activity leads to reduced net photosynthesis in the shoot and lowered root respiration, and affords an increased root/shoot ratio. The results demonstrate that roots have very limited capacity for carbon storage but exert rigid control of supply for their maintenance metabolism.}, author = {Brauner, Katrin and Hörmiller, Imke and Nägele, Thomas and Heyer, Arnd G.}, doi = {10.1111/tpj.12555}, issn = {1365-313X}, journal = {Plant J.}, number = 1, owner = {heyer}, pages = {82--91}, title = {Exaggerated root respiration accounts for growth retardation in a starchless mutant of \textit{Arabidopsis thaliana}}, url = {http://dx.doi.org/10.1111/tpj.12555}, volume = 79, year = 2014 }
Link
http://dx.doi.org/10.1111/tpj.12555
Nägele, T., Heyer, A.G.: Approximating subcellular organisation of carbohydrate metabolism during cold acclimation in different natural accessions of Arabidopsis thaliana. New Phytol. 198, 777--787 (2013). https://doi.org/10.1111/nph.12201.
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@article{Naegele2013, abstract = {Accessions of Arabidopsis thaliana originating from climatically different habitats show different levels of cold acclimation when exposed to low temperatures. The central carbohydrate metabolism plays a crucial role during this acclimation. Subcellular distribution of carbohydrates over the compartments cytosol, vacuole and plastids, and putative interactions of the compartments, are analyzed in three differentially cold-tolerant accessions of Arabidopsis thaliana, originating from the Iberian Peninsula (C24), Russia (Rschew) and Scandinavia (Tenela), respectively. * Subcellular carbohydrate concentrations were determined by applying the nonaqueous fractionation technique. Mathematical modeling and steady-state simulation was used to analyse the metabolic homeostasis during cold exposure. * In all accessions, the initial response to cold exposure was a significant increase of plastidial and cytosolic sucrose concentrations. Raffinose accumulated in all cellular compartments of cold-tolerant accessions with a delay of 3-�d, indicating that raffinose accumulation is a long-term component of cold acclimation. Minimal rates of metabolite transport permitting steady-state simulations of metabolite concentrations correlated with cold tolerance, indicating an important role of subcellular re-distribution of metabolites during cold acclimation. * A highly regulated interplay of enzymatic reactions and intracellular transport processes appears to be a prerequisite for maintaining carbohydrate homeostasis during cold exposure and allowing cold acclimation in Arabidopsis thaliana}, author = {Nägele, Thomas and Heyer, Arnd G.}, doi = {10.1111/nph.12201}, issn = {1469-8137}, journal = {New Phytol.}, month = {03}, owner = {heyer}, pages = {777--787}, refid = {45}, title = {Approximating subcellular organisation of carbohydrate metabolism during cold acclimation in different natural accessions of \textit{Arabidopsis thaliana}}, url = {http://dx.doi.org/10.1111/nph.12201}, volume = 198, year = 2013 }
Link
http://dx.doi.org/10.1111/nph.12201
Meissner, M., Orsini, E., Ruschhaupt, M., Melchinger, A.E., Hincha, D.K., Heyer, A.G.: Mapping quantitative trait loci for freezing tolerance in a recombinant inbred line population of Arabidopsis thaliana accessions Tenela and C24 reveals REVEILLE1 as negative regulator of cold acclimation. Plant Cell Environ. 36, 1256–1267 (2013). https://doi.org/10.1111/pce.12054.
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@article{Meissner2013, abstract = {The ability to increase freezing tolerance when exposed to low temperatures is a property of many plant species from temperate climates and involves a wide array of metabolic adjustments and changes in gene expression. In Arabidopsis thaliana, natural accessions show high variation in their acclimation capacity, and freezing tolerance correlates with natural habitat temperatures. To investigate the genetic basis of this variation, a recombinant inbred line population from reciprocal crosses between the accessions C24 and Tenela (Te), showing large variation in tolerance, was established. Over 250 recombinant inbred lines were genotyped for 69 single nucleotide polymorphism markers in a linkage map with 391.9 centimorgans (cM) and phenotyped for their freezing tolerance using the electrolyte leakage method that reports cell damage after a freeze-thaw cycle. Mapping of quantitative trait loci (QTL) for acclimated plants revealed three QTL regions on chromosomes 2, 4 and 5. Based on gene expression data, QTL regions were screened for genes differentially responding to low temperature in C24 and Te. Among the candidate genes, the Myb family transcription factor REVEILLE1 (At5g17300) on chromosome 5 was identified as a novel negative regulator of freezing tolerance in Arabidopsis}, author = {Meissner, M. and Orsini, E. and Ruschhaupt, M. and Melchinger, A.E. and Hincha, Dirk K. and Heyer, Arnd G.}, doi = {10.1111/pce.12054}, issn = {1365-3040}, journal = {Plant Cell Environ.}, month = {02}, owner = {heyer}, pages = {1256-1267}, refid = {48}, title = {Mapping quantitative trait loci for freezing tolerance in a recombinant inbred line population of \textit{Arabidopsis thaliana} accessions Tenela and C24 reveals REVEILLE1 as negative regulator of cold acclimation}, url = {http://dx.doi.org/10.1111/pce.12054}, volume = 36, year = 2013 }
Link
http://dx.doi.org/10.1111/pce.12054
Do, P.T., Degenkolbe, T., Erban, A., Heyer, A.G., Kopka, J., Köhl, K.I., Hincha, D.K., Zuther, E.: Dissecting Rice Polyamine Metabolism under Controlled Long-Term Drought Stress. PLOS ONE. 8, 1–14 (2013). https://doi.org/10.1371/journal.pone.0060325.
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@article{10.1371/journal.pone.0060325, abstract = {A selection of 21 rice cultivars (Oryza sativa L. ssp. indica and japonica) was characterized under moderate long-term drought stress by comprehensive physiological analyses and determination of the contents of polyamines and selected metabolites directly related to polyamine metabolism. To investigate the potential regulation of polyamine biosynthesis at the transcriptional level, the expression of 21 genes encoding enzymes involved in these pathways were analyzed by qRT-PCR. Analysis of the genomic loci revealed that 11 of these genes were located in drought-related QTL regions, in agreement with a proposed role of polyamine metabolism in rice drought tolerance. The cultivars differed widely in their drought tolerance and parameters such as biomass and photosynthetic quantum yield were significantly affected by drought treatment. Under optimal irrigation free putrescine was the predominant polyamine followed by free spermidine and spermine. When exposed to drought putrescine levels decreased markedly and spermine became predominant in all cultivars. There were no correlations between polyamine contents and drought tolerance. GC-MS analysis revealed drought-induced changes of the levels of ornithine/arginine (substrate), substrates of polyamine synthesis, proline, product of a competing pathway and GABA, a potential degradation product. Gene expression analysis indicated that ADC-dependent polyamine biosynthesis responded much more strongly to drought than the ODC-dependent pathway. Nevertheless the fold change in transcript abundance of ODC1 under drought stress was linearly correlated with the drought tolerance of the cultivars. Combining metabolite and gene expression data, we propose a model of the coordinate adjustment of polyamine biosynthesis for the accumulation of spermine under drought conditions.}, author = {Do, Phuc Thi and Degenkolbe, Thomas and Erban, Alexander and Heyer, Arnd G. and Kopka, Joachim and Köhl, Karin I. and Hincha, Dirk K. and Zuther, Ellen}, doi = {10.1371/journal.pone.0060325}, journal = {PLOS ONE}, month = {04}, number = 4, pages = {1-14}, publisher = {Public Library of Science}, title = {Dissecting Rice Polyamine Metabolism under Controlled Long-Term Drought Stress}, url = {https://doi.org/10.1371/journal.pone.0060325}, volume = 8, year = 2013 }
Link
https://doi.org/10.1371/journal.pone.0060325
Distelbarth, H., Nägele, T., Heyer, A.: Responses of antioxidant enzymes to cold and highlight are not correlated to freezing tolerance in natural accessions of Arabidopsis thaliana. Plant Biol. 15, 982--990 (2013). https://doi.org/10.1111/j.1438-8677.2012.00718.x.
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@article{Distelbarth2013, abstract = {Low temperatures and high light cause imbalances in primary and secondary reactions of photosynthesis and thus, can result in oxidative stress. Plants employ a range of low molecular weight antioxidants and antioxidant enzymes to prevent oxidative damage, and antioxidant defense is considered an important component of stress tolerance. To figure out whether oxidative stress and antioxidant defense are a key factors defining the differential cold acclimation capacities of natural accessions of the model plant �Arabidopsis thaliana�, we investigated hydrogen peroxide production, antioxidant enzyme activity and lipid peroxidation during a time course of cold treatment and exposure to high light in four differentially cold tolerant natural accessions of �Arabidopsis� (C24, Nd, Rsch, Te) that span the European distribution range of the species. All accessions except Rsch from Russia had elevated hydrogen peroxide in the cold, indicating that production of reactive oxygen species is part of the cold response in �Arabidopsis�. Glutathione reductase activity increased in all but Rsch, while ascorbate peroxidase and superoxide dismutase were unchanged and catalase decreased in all but Rsch. Under high light, the Scandinavian accession Te had elevated levels of hydrogen peroxide. Te appeared most sensitive to oxidative stress, having higher malondialdehyde (MDA) levels in the cold and under high light, while only high light caused elevated MDA in the other accessions. Although most freezing tolerant, Te displayed the highest sensitivity towards oxidative stress. No correlation was found between freezing tolerance and activity of antioxidant enzymes in the four accessions investigated, arguing against a key role of antioxidant defense in the differential cold acclimation capacities of the �Arabidopsis� accessions.}, author = {Distelbarth, H. and Nägele, T. and Heyer, A.}, doi = {10.1111/j.1438-8677.2012.00718.x}, journal = {Plant Biol.}, owner = {heyer}, pages = {982--990}, refid = {49}, title = {Responses of antioxidant enzymes to cold and highlight are not correlated to freezing tolerance in natural accessions of Arabidopsis thaliana}, volume = 15, year = 2013 }
Nägele, T., Stutz, S., Hörmiller, I.I., Heyer, A.G.: Identification of a metabolic bottleneck for cold acclimation in Arabidopsis thaliana. Plant J. 72, 102–114 (2012). https://doi.org/10.1111/j.1365-313X.2012.05064.x.
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@article{Naegele2012a, abstract = {Central carbohydrate metabolism of Arabidopsis thaliana is known to play a crucial role during cold acclimation and the acquisition of freezing tolerance. During cold exposure, many carbohydrates accumulate and a new metabolic homeostasis evolves. In the present study, we analyse the diurnal dynamics of carbohydrate homeostasis before and after cold exposure in three natural accessions showing distinct cold acclimation capacity. Diurnal dynamics of soluble carbohydrates were found to be significantly different in cold-sensitive and cold-tolerant accessions. Although experimentally determined maximum turnover rates for sucrose phosphate synthase in cold-acclimated leaves were higher for cold-tolerant accessions, model simulations of diurnal carbohydrate dynamics revealed similar fluxes. This implied a significantly higher capacity for sucrose synthesis in cold-tolerant than cold-sensitive accessions. Based on this implication resulting from mathematical model simulation, a critical temperature for sucrose synthesis was calculated using the Arrhenius equation and experimentally validated in the cold-sensitive accession C24. At the critical temperature suggested by model simulation, an imbalance in photosynthetic carbon fixation ultimately resulting in oxidative stress was observed. It is therefore concluded that metabolic capacities at least in part determine the ability of accessions of Arabidopsis thaliana to cope with changes in environmental conditions}, author = {Nägele, T. and Stutz, Simon and Hörmiller, Imke I. and Heyer, Arnd G.}, doi = {10.1111/j.1365-313X.2012.05064.x}, issn = {1365-313X}, journal = {Plant J.}, month = {05}, number = 102, owner = {heyer}, pages = {102-114}, refid = {44}, title = {Identification of a metabolic bottleneck for cold acclimation in \textit{Arabidopsis thaliana}}, url = {http://dx.doi.org/10.1111/j.1365-313X.2012.05064.x}, volume = 72, year = 2012 }
Link
http://dx.doi.org/10.1111/j.1365-313X.2012.05064.x
Zuther, E., Hoermiller, I.I., Heyer, A.G.: Evidence against sink limitation by the sucrose-to-starch route in potato plants expressing fructosyltransferases. Physiol. Plant. 143, 115--125 (2011). https://doi.org/10.1111/j.1399-3054.2011.01495.x.
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@article{Zuther2011, abstract = {To investigate whether the route from sucrose to starch limits sink strength of potato tubers, we established an additional storage carbohydrate pool and analyzed allocation of imported assimilates to the different pools. Tuber specific expression of the fructan biosynthetic enzymes of globe artichoke resulted in accumulation of fructans to about 5% of the starch level, but did not increase tuber dry weight per plant. While partial repression of starch synthesis caused yield reduction in wild-type plants, it stimulated fructan accumulation, and yield losses were ameliorated in tubers expressing fructosyltransferases. However, a nearly complete block of the starch pathway by inhibition of sucrose synthase could not be compensated by the fructan pathway. Although fructan concentrations rose, yield reduction was even enhanced, probably because of a futile cycle of fructan synthesis and degradation by invertase, which is induced when sucrose synthase is knocked out. The data do not support a limitation of sink strength by enzyme activities of the starch pathway but point to an energy limitation of storage carbohydrate formation in potato tubers.}, author = {Zuther, Ellen and Hoermiller, Imke I. and Heyer, Arnd G.}, doi = {10.1111/j.1399-3054.2011.01495.x}, issn = {1399-3054}, journal = {Physiol. Plant.}, number = 2, pages = {115--125}, publisher = {Blackwell Publishing Ltd}, title = {Evidence against sink limitation by the sucrose-to-starch route in potato plants expressing fructosyltransferases}, url = {http://dx.doi.org/10.1111/j.1399-3054.2011.01495.x}, volume = 143, year = 2011 }
Link
http://dx.doi.org/10.1111/j.1399-3054.2011.01495.x
Wingenter, K., Trentmann, O., Winschuh, I., Hörmiller, I.I., Heyer, A.G., Reinders, J., Schulz, A., Geiger, D., Hedrich, R., Neuhaus, H.E.: A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake. Plant J. 68, 890--900 (2011). https://doi.org/10.1111/j.1365-313X.2011.04739.x.
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@article{Wingenter2011, abstract = {Vacuolar solute accumulation is an important process during plant development, growth and stress responses. Although several vacuolar carriers have been identified recently, knowledge regarding the regulation of transport is still limited. Solute accumulation may be controlled by various factors, such as alterations in carrier abundance or activity. Phosphorylation via kinases is a well-known principle for activation or deactivation of proteins. Several phosphorylated proteins have been identified in the tonoplast proteome; however, kinases that catalyse the phosphorylation of tonoplast proteins are currently unknown. The tonoplast monosaccaride transporter from Arabidopsis (AtTMT1) and its homologue from barley have multiple phosphorylation sites in their extremely large loops. Here we demonstrate that the loop of AtTMT1 interacts with a mitogen-activated triple kinase-like protein kinase (VIK), that an aspartate-rich loop domain is required for effective interaction, and that the presence of VIK stimulates glucose import into isolated vacuoles. Furthermore, the phenotype of VIK loss-of-function plants strikingly resembles that of plants lacking AtTMT1/2. These data suggest that VIK-mediated phosphorylation of the AtTMT1 loop enhances carrier activity and consequently vacuolar sugar accumulation. As many phosphorylated proteins have been identified in the tonoplast, differential phosphorylation may be a general mechanism regulating vacuolar solute import.}, author = {Wingenter, Karina and Trentmann, Oliver and Winschuh, Irina and Hörmiller, Imke I. and Heyer, Arnd G. and Reinders, Jörg and Schulz, Alexander and Geiger, Dietmar and Hedrich, Rainer and Neuhaus, H. Ekkehard}, doi = {10.1111/j.1365-313X.2011.04739.x}, issn = {1365-313X}, journal = {Plant J.}, number = 5, pages = {890--900}, publisher = {Blackwell Publishing Ltd}, title = {A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake}, url = {http://dx.doi.org/10.1111/j.1365-313X.2011.04739.x}, volume = 68, year = 2011 }
Link
http://dx.doi.org/10.1111/j.1365-313X.2011.04739.x
Nägele, T., Kandel, B.A., Frana, S., Meissner, M., Heyer, A.G.: A systems biology approach for the analysis of carbohydrate dynamics during acclimation to low temperature in Arabidopsis thaliana. FEBS J. 278, 506--518 (2011). https://doi.org/10.1111/j.1742-4658.2010.07971.x.
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@article{Naegele2011, abstract = {Low temperature is an important environmental factor affecting the performance and distribution of plants. During the so-called process of cold acclimation, many plants are able to develop low-temperature tolerance, associated with the reprogramming of a large part of their metabolism. In this study, we present a systems biology approach based on mathematical modelling to determine interactions between the reprogramming of central carbohydrate metabolism and the development of freezing tolerance in two accessions of Arabidopsis thaliana. Different regulation strategies were observed for (a) photosynthesis, (b) soluble carbohydrate metabolism and (c) enzyme activities of central metabolite interconversions. Metabolism of the storage compound starch was found to be independent of accession-specific reprogramming of soluble sugar metabolism in the cold. Mathematical modelling and simulation of cold-induced metabolic reprogramming indicated major differences in the rates of interconversion between the pools of hexoses and sucrose, as well as the rate of assimilate export to sink organs. A comprehensive overview of interconversion rates is presented, from which accession-specific regulation strategies during exposure to low temperature can be derived. We propose this concept as a tool for predicting metabolic engineering strategies to optimize plant freezing tolerance. We confirm that a significant improvement in freezing tolerance in plants involves multiple regulatory instances in sucrose metabolism, and provide evidence for a pivotal role of sucrose-hexose interconversion in increasing the cold acclimation output}, author = {Nägele, T. and Kandel, B.A. and Frana, S. and Meissner, M. and Heyer, A.G.}, comment = {J}, doi = {10.1111/j.1742-4658.2010.07971.x}, issn = {1742-464X}, journal = {FEBS J.}, number = 3, owner = {heyer}, pages = {506--518}, privnote = {J}, refid = {36}, title = {A systems biology approach for the analysis of carbohydrate dynamics during acclimation to low temperature in Arabidopsis thaliana}, url = {/brokenurl#ISI:000286328400009}, volume = 278, year = 2011 }
Link
/brokenurl#ISI:000286328400009
Mishra, A., Mishra, K.B., Hoermiller, I.I., Heyer, A.G., Nedbal, L.: Chlorophyll fluorescence emission as a reporter on cold tolerance in Arabidopsis thaliana accessions. Plant Signaling Behav. 6, 301--310 (2011). https://doi.org/10.4161/psb.6.2.15278.
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@article{Mishra2011, abstract = {Non-invasive, high-throughput screening methods are valuable tools in breeding for abiotic stress tolerance in plants. Optical signals such as chlorophyll fluorescence emission can be instrumental in developing new screening techniques. In order to examine the potential of chlorophyll fluorescence to reveal plant tolerance to low temperatures, we used a collection of nine Arabidopsis thaliana accessions and compared their fluorescence features with cold tolerance quantified by the well established electrolyte leakage method on detached leaves. We found that, during progressive cooling, the minimal chlorophyll fluorescence emission rose strongly and that this rise was highly dependent on the cold tolerance of the accessions. Maximum quantum yield of PSII photochemistry and steady state fluorescence normalized to minimal fluorescence were also highly correlated to the cold tolerance measured by the electrolyte leakage method. In order to further increase the capacity of the fluorescence detection to reveal the low temperature tolerance, we applied combinatorial imaging that employs plant classification based on multiple fluorescence features. We found that this method, by including the resolving power of several fluorescence features, can be well employed to detect cold tolerance already at mild sub-zero temperatures. Therefore, there is no need to freeze the screened plants to the largely damaging temperatures of around -15�C. This, together with the method's easy applicability, represents a major advantage of the fluorescence technique over the conventional electrolyte leakage method.}, author = {Mishra, A. and Mishra, K.B. and Hoermiller, I.I. and Heyer, A.G. and Nedbal, L.}, doi = {10.4161/psb.6.2.15278}, journal = {Plant Signaling Behav.}, month = {02}, number = 2, owner = {heyer}, pages = {301--310}, refid = {40}, title = {Chlorophyll fluorescence emission as a reporter on cold tolerance in \textit{Arabidopsis thaliana} accessions}, url = {https://www.tandfonline.com/doi/abs/10.4161/psb.6.2.15278}, volume = 6, year = 2011 }
Link
https://www.tandfonline.com/doi/abs/10.4161/psb.6.2.15278
Knaupp, M., Mishra, K.B., Nedbal, L., Heyer, A.G.: Evidence for a role of raffinose in stabilizing photosystem II during freeze--thaw cycles. Planta. 234, 477--486 (2011). https://doi.org/10.1007/s00425-011-1413-0.
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@article{Knaupp2011, abstract = {A role of non-reducing sugars like sucrose and raffinose in the protection of plant cells against damage during freezing has been proposed for many species, but reports on physiological effects are conflicting. Non-aqueous fractionation of mesophyll cell compartments in Arabidopsis thaliana was used to show that sucrose and raffinose accumulate in plastids during low temperatures, pointing to a physiological role in protecting the photosynthetic apparatus. Comparing a previously described raffinose synthase (RS) mutant of A. thaliana with its corresponding wild type, accession Col-0, revealed that a lack of raffinose has no effect on electrolyte leakage from leaf cells after freeze--thaw cycles, supporting that raffinose is not essential for protecting the plasma membrane. However, in situ chlorophyll fluorescence showed that maximum quantum yield of PS II photochemistry (F v/F m) and other fluorescence parameters of cold acclimated leaves subjected to freeze--thaw cycles were significantly lower in the raffinose synthase mutant than in the corresponding wild type, indicating that raffinose is involved in stabilizing PS II of cold acclimated leaf cells against damage during freezing.}, author = {Knaupp, Markus and Mishra, Kumud B. and Nedbal, Ladislav and Heyer, Arnd G.}, day = 01, doi = {10.1007/s00425-011-1413-0}, issn = {1432-2048}, journal = {Planta}, month = {09}, number = 3, pages = {477--486}, title = {Evidence for a role of raffinose in stabilizing photosystem II during freeze--thaw cycles}, url = {https://doi.org/10.1007/s00425-011-1413-0}, volume = 234, year = 2011 }
Link
https://doi.org/10.1007/s00425-011-1413-0
Iftime, D., Hannah, M.A., Peterbauer, T., Heyer, A.G.: Stachyose in the cytosol does not influence freezing tolerance of transgenic Arabidopsis expressing stachyose synthase from adzuki bean. Plant Science. 180, 24--30 (2011). https://doi.org/10.1016/j.plantsci.2010.07.012.
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@article{Iftime_2011, author = {Iftime, Dumitrita and Hannah, Matthew A. and Peterbauer, Thomas and Heyer, Arnd G.}, doi = {10.1016/j.plantsci.2010.07.012}, journal = {Plant Science}, month = {01}, number = 1, pages = {24--30}, publisher = {Elsevier {BV}}, title = {Stachyose in the cytosol does not influence freezing tolerance of transgenic Arabidopsis expressing stachyose synthase from adzuki bean}, url = {https://doi.org/10.1016%2Fj.plantsci.2010.07.012}, volume = 180, year = 2011 }
Link
https://doi.org/10.1016%2Fj.plantsci.2010.07.012
Henkel, S., Nägele, T., Hörmiller, I., Sauter, T., Sawodny, O., Ederer, M., Heyer, A.G.: A systems biology approach to analyse leaf carbohydrate metabolism in Arabidopsis thaliana. EURASIP Journal on Bioinformatics and Systems Biology. 2011, 2 (2011). https://doi.org/10.1186/1687-4153-2011-2.
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@article{Henkel_2011, author = {Henkel, Sebastian and Nägele, Thomas and Hörmiller, Imke and Sauter, Thomas and Sawodny, Oliver and Ederer, Michael and Heyer, Arnd G}, doi = {10.1186/1687-4153-2011-2}, journal = {{EURASIP} Journal on Bioinformatics and Systems Biology}, month = {06}, number = 1, pages = 2, publisher = {Springer Nature}, title = {A systems biology approach to analyse leaf carbohydrate metabolism in Arabidopsis thaliana}, url = {https://doi.org/10.1186%2F1687-4153-2011-2}, volume = 2011, year = 2011 }
Link
https://doi.org/10.1186%2F1687-4153-2011-2
Hengherr, S., Heyer, A.G., Brümmer, F., Schill, R.O.: Trehalose and Vitreous States: Desiccation Tolerance of Dormant Stages of the Crustaceans Triops and Daphnia. Physiological and Biochemical Zoology: Ecological and Evolutionary Approaches. 84, 147--153 (2011). https://doi.org/10.1086/658499.
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@article{Hengherr2011, abstract = {AbstractSeveral aquatic organisms are able to withstand extreme desiccation in at least one of their life stages. This is commonly known as “anhydrobiosis.” It was often thought that to tolerate such a desiccated state required high amounts of compatible solutes such as the nonreducing disaccharide trehalose, which protects cellular structures by water replacement and glass formation. Trehalose levels of dormant eggs and cysts of five freshwater crustaceans (Daphnia magna, Daphnia pulex, Triops longicaudatus, Triops cancriformis, and Triops australiensis) were observed in different states of hydration and dehydration. Although trehalose was detected in all species, the concentration was under 0.5% of the dry weight (0.05 μg/μg protein), and no change between the different states was observed. Differential scanning calorimetry (DSC) measurements indicated that dried cysts of all Triops species were in a glassy state, supporting the vitrification hypothesis. No indication for a vitreous state was found in dried resting eggs of Daphnia.}, author = {Hengherr, S. and Heyer, A. G. and Brümmer, F. and Schill, R. O.}, doi = {10.1086/658499}, issn = {15222152, 15375293}, journal = {Physiological and Biochemical Zoology: Ecological and Evolutionary Approaches}, month = {03}, number = 2, pages = {147--153}, publisher = {[The University of Chicago Press, Division of Comparative Physiology and Biochemistry, Society for Integrative and Comparative Biology]}, title = {Trehalose and Vitreous States: Desiccation Tolerance of Dormant Stages of the Crustaceans Triops and Daphnia}, url = {http://www.jstor.org/stable/10.1086/658499}, volume = 84, year = 2011 }
Link
http://www.jstor.org/stable/10.1086/658499
Wingenter, K., Schulz, A., Wormit, A., Wic, S., Trentmann, O., Hoermiller, I.I., Heyer, A.G., Marten, I., Hedrich, R., Neuhaus, H.E.: Increased Activity of the Vacuolar Monosaccharide Transporter TMT1 Alters Cellular Sugar Partitioning, Sugar Signaling, and Seed Yield in Arabidopsis. Plant Physiol. 154, 665--677 (2010). https://doi.org/10.1104/pp.110.162040.
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@article{Wingenter2010, abstract = {The extent to which vacuolar sugar transport activity affects molecular, cellular, and developmental processes in Arabidopsis (Arabidopsis thaliana) is unknown. Electrophysiological analysis revealed that overexpression of the tonoplast monosaccharide transporter TMT1 in a tmt1-2::tDNA mutant led to increased proton-coupled monosaccharide import into isolated mesophyll vacuoles in comparison with wild-type vacuoles. TMT1 overexpressor mutants grew faster than wild-type plants on soil and in high-glucose (Glc)-containing liquid medium. These effects were correlated with increased vacuolar monosaccharide compartmentation, as revealed by nonaqueous fractionation and by chlorophyll(ab)-binding protein1 and nitrate reductase1 gene expression studies. Soil-grown TMT1 overexpressor plants respired less Glc than wild-type plants and only about half the amount of Glc respired by tmt1-2::tDNA mutants. In sum, these data show that TMT activity in wild-type plants limits vacuolar monosaccharide loading. Remarkably, TMT1 overexpressor mutants produced larger seeds and greater total seed yield, which was associated with increased lipid and protein content. These changes in seed properties were correlated with slightly decreased nocturnal CO2 release and increased sugar export rates from detached source leaves. The SUC2 gene, which codes for a sucrose transporter that may be critical for phloem loading in leaves, has been identified as Glc repressed. Thus, the observation that SUC2 mRNA increased slightly in TMT1 overexpressor leaves, characterized by lowered cytosolic Glc levels than wild-type leaves, provided further evidence of a stimulated source capacity. In summary, increased TMT activity in Arabidopsis induced modified subcellular sugar compartmentation, altered cellular sugar sensing, affected assimilate allocation, increased the biomass of Arabidopsis seeds, and accelerated early plant development}, author = {Wingenter, K. and Schulz, A. and Wormit, A. and Wic, S. and Trentmann, O. and Hoermiller, I.I. and Heyer, A.G. and Marten, I. and Hedrich, R. and Neuhaus, H.E.}, comment = {J}, doi = {10.1104/pp.110.162040}, issn = {0032-0889}, journal = {Plant Physiol.}, number = 2, owner = {heyer}, pages = {665--677}, privnote = {J}, refid = {38}, title = {Increased Activity of the Vacuolar Monosaccharide Transporter TMT1 Alters Cellular Sugar Partitioning, Sugar Signaling, and Seed Yield in \textit{Arabidopsis}}, url = {http://www.plantphysiol.org/content/154/2/665}, volume = 154, year = 2010 }
Link
http://www.plantphysiol.org/content/154/2/665
Nägele, T., Henkel, S., Hörmiller, I., Sauter, T., Sawodny, O., Ederer, M., Heyer, A.G.: Mathematical modeling of the central carbohydrate metabolism in Arabidopsis reveals a substantial regulatory influence of vacuolar invertase on whole plant carbon metabolism. Plant Physiol. 153, 260--272 (2010). https://doi.org/10.1104/pp.110.154443.
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@article{Naegele2010, abstract = {A mathematical model representing metabolite interconversions in the central carbohydrate metabolism of Arabidopsis (Arabidopsis thaliana) was developed to simulate the diurnal dynamics of primary carbon metabolism in a photosynthetically active plant leaf. The model groups enzymatic steps of central carbohydrate metabolism into blocks of interconverting reactions that link easily measurable quantities like CO2 exchange and quasi-steady-state levels of soluble sugars and starch. When metabolite levels that fluctuate over diurnal cycles are used as a basic condition for simulation, turnover rates for the interconverting reactions can be calculated that approximate measured metabolite dynamics and yield kinetic parameters of interconverting reactions. We used experimental data for Arabidopsis wild-type plants, accession Columbia, and a mutant defective in vacuolar invertase, At beta Fruct4, as input data. Reducing invertase activity to mutant levels in the wild-type model led to a correct prediction of increased sucrose levels. However, additional changes were needed to correctly simulate levels of hexoses and sugar phosphates, indicating that invertase knockout causes subsequent changes in other enzymatic parameters. Reduction of invertase activity caused a decline in photosynthesis and export of reduced carbon to associated metabolic pathways and sink organs (e. g. roots), which is in agreement with the reported contribution of vacuolar invertase to sink strength. According to model parameters, there is a role for invertase in leaves, where futile cycling of sucrose appears to have a buffering effect on the pools of sucrose, hexoses, and sugar phosphates. Our data demonstrate that modeling complex metabolic pathways is a useful tool to study the significance of single enzyme activities in complex, nonintuitive networks}, author = {Nägele, T. and Henkel, S. and Hörmiller, I. and Sauter, T. and Sawodny, O. and Ederer, M. and Heyer, A.G.}, comment = {J}, doi = {10.1104/pp.110.154443}, issn = {0032-0889}, journal = {Plant Physiol.}, number = 1, owner = {heyer}, pages = {260--272}, privnote = {J}, refid = {39}, title = {Mathematical modeling of the central carbohydrate metabolism in \textit{Arabidopsis} reveals a substantial regulatory influence of vacuolar invertase on whole plant carbon metabolism}, url = {http://www.plantphysiol.org/content/153/1/260?keytype=ref&ijkey=fjFkF7ugYYBybHo}, volume = 153, year = 2010 }
Link
http://www.plantphysiol.org/content/153/1/260?keytype=ref&ijkey=fjFkF7ugYYBybHo
Livingston, D.P., Hincha, D.K., Heyer, A.G.: Fructan and its relationship to abiotic stress tolerance in plants. Cellular and Molecular Life Sciences. 66, 2007--2023 (2009). https://doi.org/10.1007/s00018-009-0002-x.
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@article{Livingston2009, abstract = {Numerous studies have been published that attempted to correlate fructan concentrations with freezing and drought tolerance. Studies investigating the effect of fructan on liposomes indicated that a direct interaction between membranes and fructan was possible. This new area of research began to move fructan and its association with stress beyond mere correlation by confirming that fructan has the capacity to stabilize membranes during drying by inserting at least part of the polysaccharide into the lipid headgroup region of the membrane. This helps prevent leakage when water is removed from the system either during freezing or drought. When plants were transformed with the ability to synthesize fructan, a concomitant increase in drought and/or freezing tolerance was confirmed. These experiments indicate that besides an indirect effect of supplying tissues with hexose sugars, fructan has a direct protective effect that can be demonstrated by both model systems and genetic transformation.}, author = {Livingston, David P. and Hincha, Dirk K. and Heyer, Arnd G.}, day = 01, doi = {10.1007/s00018-009-0002-x}, issn = {1420-9071}, journal = {Cellular and Molecular Life Sciences}, month = {07}, number = 13, pages = {2007--2023}, title = {Fructan and its relationship to abiotic stress tolerance in plants}, url = {https://doi.org/10.1007/s00018-009-0002-x}, volume = 66, year = 2009 }
Link
https://doi.org/10.1007/s00018-009-0002-x
Korn, M., Peterek, S., Mock, H.P., Heyer, A.G., Hincha, D.K.: Heterosis in the freezing tolerance, and sugar and flavonoid contents of crosses between Arabidopsis thaliana accessions of widely varying freezing tolerance. Plant Cell Environ. 31, 813--827 (2008). https://doi.org/10.1111/j.1365-3040.2008.01800.x.
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@article{Korn2008, abstract = {Heterosis is defined as the increased vigour of hybrids in comparison to their parents. We investigated 24 F-1 hybrid lines of Arabidopsis thaliana generated by reciprocally crossing either C24 or Col with six other parental accessions (Can, Co, Cvi, Ler, Rsch, Te) that differ widely in their freezing tolerance. The crosses differed in the degree of heterosis for freezing tolerance, both in the non-acclimated state and after a 14 d cold acclimation period. Crosses with C24 showed more heterosis than crosses with Col, and heterosis was stronger in acclimated than in non-acclimated plants. Leaf content of soluble sugars and proline showed more deviation from mid-parent values in crosses involving C24 than in those involving Col, and deviations were larger in acclimated than in non-acclimated plants. There were significant correlations between the content of different sugars and leaf freezing tolerance, as well as between heterosis effects in freezing tolerance and sugar content. Flavonoid content and composition varied between accessions, and between non-acclimated and acclimated plants. In the crosses, large deviations from the mid-parent values in the contents of different flavonols occurred, and there were strikingly strong correlations between both flavonol content and freezing tolerance, and between heterosis effects in freezing tolerance and flavonol content. [References: 48]}, author = {Korn, M. and Peterek, S. and Mock, H.P. and Heyer, A.G. and Hincha, D.K.}, comment = {DB - Current Contents PT - Article <2>}, doi = {10.1111/j.1365-3040.2008.01800.x}, journal = {Plant Cell Environ.}, month = {06}, number = 6, owner = {heyer}, pages = {813--827}, privnote = {DB - Current Contents PT - Article <2>}, refid = {1}, title = {Heterosis in the freezing tolerance, and sugar and flavonoid contents of crosses between \textit{Arabidopsis thaliana} accessions of widely varying freezing tolerance}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3040.2008.01800.x}, volume = 31, year = 2008 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3040.2008.01800.x
Hengherr, S., Heyer, A.G., Kohler, H.R., Schill, R.O.: Trehalose and anhydrobiosis in tardigrades - evidence for divergence in responses to dehydration. FEBS J. 275, 281--288 (2008). https://doi.org/10.1111/j.1742-4658.2007.06198.x.
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@article{Hengherr2008, abstract = {To withstand desiccation, many invertebrates such as rotifers, nematodes and tardigrades enter a state known as anhydrobiosis, which is thought to require accumulation of compatible osmolytes, such as the non-reducing disaccharide trehalose to protect against dehydration damage. The trehalose levels of eight tardigrade species comprising Heterotardigrada and Eutardigrada were observed in five different states of hydration and dehydration. Although many species accumulate trehalose during dehydration, the data revealed significant differences between the species. Although trehalose accumulation was found in species of the order Parachela (Eutardigrada), it was not possible to detect any trehalose in the species Milnesium tardigradum and no change in the trehalose level has been observed in any species of Heterotardigrada so far investigated. These results expand our current understanding of anhydrobiosis in tardigrades and, for the first time, demonstrate the accumulation of trehalose in developing tardigrade embryos, which have been shown to have a high level of desiccation tolerance. [References: 57]}, author = {Hengherr, S. and Heyer, A.G. and Kohler, H.R. and Schill, R.O.}, comment = {DB - Current Contents PT - Article <3>}, doi = {10.1111/j.1742-4658.2007.06198.x}, journal = {FEBS J.}, month = {01}, number = 2, owner = {heyer}, pages = {281--288}, privnote = {DB - Current Contents PT - Article <3>}, refid = {2}, title = {Trehalose and anhydrobiosis in tardigrades - evidence for divergence in responses to dehydration}, url = {https://febs.onlinelibrary.wiley.com/doi/full/10.1111/j.1742-4658.2007.06198.x}, volume = 275, year = 2008 }
Link
https://febs.onlinelibrary.wiley.com/doi/full/10.1111/j.1742-4658.2007.06198.x
Hincha, D.K., Livingston, D.P., Premakumar, R., Zuther, E., Obel, N., Cacela, C., Heyer, A.G.: Fructans from oat and rye: Composition and effects on membrane stability during drying. Biochimica et Biophysica Acta (BBA) - Biomembranes. 1768, 1611--1619 (2007). https://doi.org/10.1016/j.bbamem.2007.03.011.
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@article{Hincha_2007, author = {Hincha, Dirk K. and Livingston, David P. and Premakumar, Ramaswamy and Zuther, Ellen and Obel, Nicolai and Cacela, Constan{\c{c}}a and Heyer, Arnd G.}, doi = {10.1016/j.bbamem.2007.03.011}, journal = {Biochimica et Biophysica Acta ({BBA}) - Biomembranes}, month = {06}, number = 6, pages = {1611--1619}, publisher = {Elsevier {BV}}, title = {Fructans from oat and rye: Composition and effects on membrane stability during drying}, url = {https://doi.org/10.1016%2Fj.bbamem.2007.03.011}, volume = 1768, year = 2007 }
Link
https://doi.org/10.1016%2Fj.bbamem.2007.03.011
Hannah, M.A., Kramer, K.M., Geffroy, V., Kopka, J., Blair, M.W., Erban, A., Vallejos, C.E., Heyer, A.G., Sanders, F.E.T., Millner, P.A., Pilbeam, D.J.: Hybrid weakness controlled by the dosage-dependent lethal (DL) gene system in common bean (Phaseolus vulgaris) is caused by a shoot-derived inhibitory signal leading to salicylic acid-associated root death. New Phytol. 176, 537--549 (2007). https://doi.org/10.1111/j.1469-8137.2007.02215.x.
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@article{Hannah2007, abstract = {Certain crosses of common bean (Phaseolus vulgaris) result in temperature-dependent hybrid weakness associated with a severe root phenotype. This is controlled by the interaction of the root- and shoot-expressed semidominant alleles dosage-dependent lethal 1 (DL1) and DL2, which communicate via long-distance signaling. Previously, apparent reciprocal effects on root growth and the restoration of normal root growth by exogenous sucrose led to the hypothesis that the dosage-dependent lethal (DL) system may control root-shoot carbon partitioning. Here, recombinant inbred lines were used to map the DL loci and physiological and biochemical analysis, including metabolite profiling, was used to gain new insights into the signaling interaction and the root phenotype. It is shown that the DL system does not control root-shoot carbon partitioning and that roots are unlikely to die from carbon starvation. Instead, root death likely occurs by defense-related programmed cell death, as indicated by salicylic acid accumulation. DL2-expressing cotyledons supply a potent inhibitory signal that is sufficient to cause such death in DL1-expressing roots. These data implicate the DL system in defense-related signaling and provide support for the recent hypothesis of defense-related autoimmunity as a potential isolating mechanism in plant speciation, in particular, setting a precedence for the potential roles of long-distance signaling and temperature dependence. [References: 38]}, author = {Hannah, M.A. and Kramer, K.M. and Geffroy, V. and Kopka, J. and Blair, M.W. and Erban, A. and Vallejos, C.E. and Heyer, A.G. and Sanders, F.E.T. and Millner, P.A. and Pilbeam, D.J.}, comment = {DB - Current Contents PT - Article <4>}, doi = {10.1111/j.1469-8137.2007.02215.x}, journal = {New Phytol.}, number = 3, owner = {heyer}, pages = {537--549}, privnote = {DB - Current Contents PT - Article <4>}, refid = {3}, title = {Hybrid weakness controlled by the dosage-dependent lethal (DL) gene system in common bean (\textit{Phaseolus vulgaris}) is caused by a shoot-derived inhibitory signal leading to salicylic acid-associated root death}, url = {https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-8137.2007.02215.x}, volume = 176, year = 2007 }
Link
https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-8137.2007.02215.x
Hannah, M.A., Zuther, E., Buchel, K., Heyer, A.G.: Transport and metabolism of raffinose family oligosaccharides in transgenic potato. J. Exp. Bot. 57, 3801--3811 (2006). https://doi.org/10.1093/jxb/erl152.
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@article{Hannah2006a, abstract = {Raffinose family oligosaccharides (RFOs) are involved in the storage and transport of carbon and serve as compatible solutes for protection against abiotic stresses like drought or cold. RFOs are usually transported in plant species that load sugars symplastically into the phloem. Loading probably occurs by a polymer trapping mechanism which establishes a concentration gradient of assimilates between the mesophyll and the vasculature. Transgenic approaches have demonstrated phloem transport of small molecules produced in the companion cells of apoplastic loading species, but these molecules have been non-native transport substances to plants. In this study, transgenic potato plants with constitutive or companion cell specific overexpression of galactinol synthase (GS) or GS plus raffinose synthase (RS) are characterized, which together provide new insights into the metabolism and transport of RFOs in plants. It is demonstrated that raffinose and galactinol are both transported in the phloem and that, whilst the effect of GS overexpression is promoter-independent, that of RS is dependent on the promoter used. The presence of significant amounts of galactinol in the phloem is shown and also that transgenic potato is unable to transport large amounts of raffinose despite high RS expression and substrate concentrations. These data indicate that there may be additional features of intermediary cells, the specialized companion cells of RFO transporting plants, required for significant RFO synthesis and transport that are currently not well-understood. [References: 35]}, author = {Hannah, M.A. and Zuther, E. and Buchel, K. and Heyer, A.G.}, comment = {DB - Current Contents PT - Article <5>}, doi = {10.1093/jxb/erl152}, journal = {J. Exp. Bot.}, month = {11}, number = 14, owner = {heyer}, pages = {3801--3811}, privnote = {DB - Current Contents PT - Article <5>}, refid = {4}, title = {Transport and metabolism of raffinose family oligosaccharides in transgenic potato}, url = {https://academic.oup.com/jxb/article/57/14/3801/586863}, volume = 57, year = 2006 }
Link
https://academic.oup.com/jxb/article/57/14/3801/586863
Hannah, M.A., Wiese, D., Freund, S., Fiehn, O., Heyer, A.G., Hincha, D.K.: Natural genetic variation of freezing tolerance in Arabidopsis. Plant Physiol. 142, 98--112 (2006). https://doi.org/10.1104/pp.106.081141.
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@article{Hannah2006, abstract = {Low temperature is a primary determinant of plant growth and survival. Using accessions of Arabidopsis (Arabidopsis thaliana) originating from Scandinavia to the Cape Verde Islands, we show that freezing tolerance of natural accessions correlates with habitat winter temperatures, identifying low temperature as an important selective pressure for Arabidopsis. Combined metabolite and transcript profiling show that during cold exposure, global changes of transcripts, but not of metabolites, correlate with the ability of Arabidopsis to cold acclimate. There are, however, metabolites and transcripts, including several transcription factors, that correlate with freezing tolerance, indicating regulatory pathways that may be of primary importance for this trait. These data identify that enhanced freezing tolerance is associated with the down-regulation of photosynthesis and hormonal responses and the induction of flavonoid metabolism, provide evidence for naturally increased nonacclimated freezing tolerance due to the constitutive activation of the C-repeat binding factors pathway, and identify candidate transcriptional regulators that correlate with freezing tolerance. [References: 61]}, author = {Hannah, M.A. and Wiese, D. and Freund, S. and Fiehn, O. and Heyer, A.G. and Hincha, D.K.}, comment = {DB - Current Contents PT - Article <6>}, doi = {10.1104/pp.106.081141}, journal = {Plant Physiol.}, month = {09}, number = 1, owner = {heyer}, pages = {98--112}, privnote = {DB - Current Contents PT - Article <6>}, refid = {5}, title = {Natural genetic variation of freezing tolerance in \textit{Arabidopsis}}, url = {http://www.plantphysiol.org/content/142/1/98}, volume = 142, year = 2006 }
Link
http://www.plantphysiol.org/content/142/1/98
Hannah, M.A., Heyer, A.G., Hincha, D.K.: A Global Survey of Gene Regulation during Cold Acclimation in Arabidopsis thaliana. PLOS Genetics. 1, (2005). https://doi.org/10.1371/journal.pgen.0010026.
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@article{10.1371/journal.pgen.0010026, abstract = {Many temperate plant species such as Arabidopsis thaliana are able to increase their freezing tolerance when exposed to low, nonfreezing temperatures in a process called cold acclimation. This process is accompanied by complex changes in gene expression. Previous studies have investigated these changes but have mainly focused on individual or small groups of genes. We present a comprehensive statistical analysis of the genome-wide changes of gene expression in response to 14 d of cold acclimation in Arabidopsis, and provide a large-scale validation of these data by comparing datasets obtained for the Affymetrix ATH1 Genechip and MWG 50-mer oligonucleotide whole-genome microarrays. We combine these datasets with existing published and publicly available data investigating Arabidopsis gene expression in response to low temperature. All data are integrated into a database detailing the cold responsiveness of 22,043 genes as a function of time of exposure at low temperature. We concentrate our functional analysis on global changes marking relevant pathways or functional groups of genes. These analyses provide a statistical basis for many previously reported changes, identify so far unreported changes, and show which processes predominate during different times of cold acclimation. This approach offers the fullest characterization of global changes in gene expression in response to low temperature available to date.}, author = {Hannah, Matthew A and Heyer, Arnd G and Hincha, Dirk K}, doi = {10.1371/journal.pgen.0010026}, journal = {PLOS Genetics}, month = {08}, number = 2, publisher = {Public Library of Science}, title = {A Global Survey of Gene Regulation during Cold Acclimation in Arabidopsis thaliana}, url = {https://doi.org/10.1371/journal.pgen.0010026}, volume = 1, year = 2005 }
Link
https://doi.org/10.1371/journal.pgen.0010026
Degenkolbe, T., Hannah, M.A., Freund, S., Hincha, D.K., Heyer, A.G., Köhl, K.I.: A quality-controlled microarray method for gene expression profiling. Analytical Biochemistry. 346, 217--224 (2005). https://doi.org/10.1016/j.ab.2005.08.027.
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@article{Degenkolbe_2005, author = {Degenkolbe, Thomas and Hannah, Matthew A. and Freund, Susanne and Hincha, Dirk K. and Heyer, Arnd G. and Köhl, Karin I.}, doi = {10.1016/j.ab.2005.08.027}, journal = {Analytical Biochemistry}, month = {11}, number = 2, pages = {217--224}, publisher = {Elsevier {BV}}, title = {A quality-controlled microarray method for gene expression profiling}, url = {https://doi.org/10.1016%2Fj.ab.2005.08.027}, volume = 346, year = 2005 }
Link
https://doi.org/10.1016%2Fj.ab.2005.08.027
Zuther, E., Kwart, M., Willmitzer, L., Heyer, A.G.: Expression of a yeast-derived invertase in companion cells results in long-distance transport of a trisaccharide in an apoplastic loader and influences sucrose transport. Planta. 218, 759--766 (2004). https://doi.org/10.1007/s00425-003-1148-7.
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@article{Zuther2004, abstract = {Companion cell-specific expression of a cytosolic invertase from yeast (Saccharomyces cerevisiae) was used as a tool to synthesise oligosaccharides in the sieve element/companion cell complex and study whether oligosaccharides could be transported in the phloem of an apoplastically loading species. Potato (Solanum tuberosum L.) plants expressing the invertase under the control of the Agrobacterium tumefaciens rolC promoter produced the trisaccharide 6-kestose in leaves, which was transported via the phloem and accumulated in tubers of transgenic plants. In graft experiments with rolC invertase plants as scion and wild-type rootstocks, 6-kestose accumulated in tubers to levels comparable to sucrose. This shows that long-distance transport of oligosaccharides is possible in apoplastically loading plants, which normally transport only sucrose. The additional transport route for assimilates neither led to elevated photosynthetic activity nor to increased tuber yield. Enhanced sucrose turnover in companion cells caused large amounts of glucose and fructose to be exuded from leaf petioles, and elevated levels of sucrose were detected in phloem exudates. While the latter indicates a higher capacity for sucrose loading into the phloem due to increased metabolic activity of companion cells, the massive release of hexoses catalysed by the invertase seemed to interfere with assimilate delivery to sink organs.}, author = {Zuther, Ellen and Kwart, Marion and Willmitzer, Lothar and Heyer, Arnd G.}, day = 01, doi = {10.1007/s00425-003-1148-7}, issn = {1432-2048}, journal = {Planta}, month = {03}, number = 5, pages = {759--766}, title = {Expression of a yeast-derived invertase in companion cells results in long-distance transport of a trisaccharide in an apoplastic loader and influences sucrose transport}, url = {https://doi.org/10.1007/s00425-003-1148-7}, volume = 218, year = 2004 }
Link
https://doi.org/10.1007/s00425-003-1148-7
Zuther, E., Büchel, K., Hundertmark, M., Stitt, M., Hincha, D.K., Heyer, A.G.: The role of raffinose in the cold acclimation response of Arabidopsis thaliana. FEBS Lett. 576, 169--173 (2004).
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@article{Zuther2004, abstract = {In many plants raffinose family oligosaccharides are accumulated during cold acclimation. The contribution of raffinose accumulation to freezing tolerance is not clear. Here, we investigated whether synthesis of raffinose is an essential component for acquiring frost tolerance. We created transgenic lines of Arabidopsis thaliana accessions Columbia-0 and Cape Verde Islands constitutively overexpressing a galactinol synthase (GS) gene from cucumber. GS overexpressing lines contained up to 20 times as much raffinose as the respective wild type under non-acclimated conditions and up to 2.3 times more after 14 days of cold acclimation at 4degreesC. Furthermore, we used a mutant carrying a knockout of the endogenous raffinose synthase (RS) gene. Raffinose was completely absent in this mutant. However, neither the freezing tolerance of non-acclimated leaves, nor their ability to cold acclimate were influenced in the RS mutant or in the G overexpressing lines. We conclude that raffinose is not essential for basic freezing tolerance or for cold acclimation of A. thaliana. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved. [References: 30]}, author = {Zuther, E. and Büchel, K. and Hundertmark, M. and Stitt, M. and Hincha, D.K. and Heyer, A.G.}, comment = {DB - Current Contents PT - Article <9>}, journal = {FEBS Lett.}, month = {10}, number = {1-2}, owner = {heyer}, pages = {169--173}, privnote = {DB - Current Contents PT - Article <9>}, refid = {8}, title = {The role of raffinose in the cold acclimation response of Arabidopsis thaliana}, volume = 576, year = 2004 }
Rohde, P., Hincha, D.K., Heyer, A.G.: Heterosis in the freezing tolerance of crosses between two Arabidopsis thaliana accessions (Columbia-0 and C24) that show differences in non-acclimated and acclimated freezing tolerance. The Plant Journal. 38, 790–799 (2004). https://doi.org/10.1111/j.1365-313X.2004.02080.x.
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@article{rohde2004, abstract = {Summary Heterosis is broadly defined as the increased vigour of hybrids in comparison to their parents. In the model plant Arabidopsis thaliana, a significant heterosis effect on leaf-freezing tolerance was observed in the F1 generation of a cross between the accessions Columbia-0 (Col) and C24. Parental Col plants were significantly more freezing-tolerant than C24 plants in both the acclimated and non-acclimated (NA) states. Mid-parent heterosis was observed in the F1 plants, both in the basic tolerance of non-adapted plants and in freezing tolerance after cold acclimation. Best-parent heterosis, on the other hand, was only found after cold acclimation. The heterosis effect was reduced in the F2 populations such that only mid-parent heterosis was evident. The leaf content of soluble sugars (fructose (Fru), glucose (Glc), sucrose (Suc) and raffinose (Raf)) increased dramatically in the F1 plants after cold acclimation as compared to the parental lines. The content of proline (Pro), however, was only moderately increased in the F1 plants under the same conditions. Correlation analyses showed that only Raf content was consistently related to leaf-freezing tolerance in both the acclimated and NA states. A quantification of mRNA levels in leaves of parental and F1 lines using quantitative real-time RT-PCR showed no clear indication for an involvement of the investigated genes (CBF (C-repeat binding factor)1, CBF2, (cold-regulated protein (COR) 6.6, COR15a, COR15b, COR47 and COR78) in the heterosis effect. }, author = {Rohde, Peter and Hincha, Dirk K. and Heyer, Arnd G.}, doi = {10.1111/j.1365-313X.2004.02080.x}, journal = {The Plant Journal}, pages = {790-799}, series = 5, title = {Heterosis in the freezing tolerance of crosses between two Arabidopsis thaliana accessions (Columbia-0 and C24) that show differences in non-acclimated and acclimated freezing tolerance}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-313X.2004.02080.x}, volume = 38, year = 2004 }
Link
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-313X.2004.02080.x
Klotke, J., Kopka, J., Gatzke, N., Heyer, A.G.: Impact of soluble sugar concentrations on the acquisition of freezing tolerance in accessions of Arabidopsis thaliana with contrasting cold adaptation - evidence for a role of raffinose in cold acclimation. Plant Cell Environ. 27, 1395--1404 (2004).
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@article{Klotke2004, abstract = {In the present study the cold acclimation potential of two accessions of Arabidopsis thaliana was investigated. Significant variation was found for basic tolerance as well as the capacity to acclimate to freezing temperatures. During cold acclimation, levels of soluble sugars increased in both genotypes, but raffinose accumulation discriminated the more tolerant accession Col-0 from C24. Concentrations of other compatible solutes such as proline and glutamine were also higher in cold-acclimated Col-0 than C24 plants. Changes of invertase activity during cold exposure corresponded to changes in sucrose and fructose, but not glucose concentrations and were consistent with an initial chilling response and a later decline in hexose metabolization. When vacuolar invertase was suppressed by siRNA expression, reduced sucrolytic activity resulted in elevated leaf sucrose concentration, whereas the fructose content was strongly reduced. This led to elevated freezing tolerance in the cold-tolerant genotype Col-0, but not in C24. The most pronounced metabolic changes in invertase-inhibited Col-0 plants occurred for proline and glutamine concentrations, indicating indirect metabolic effects of altered sugar concentrations. [References: 38]}, author = {Klotke, J. and Kopka, J. and Gatzke, N. and Heyer, A.G.}, comment = {DB - Current Contents PT - Article <8>}, journal = {Plant Cell Environ.}, month = {11}, number = 11, owner = {heyer}, pages = {1395--1404}, privnote = {DB - Current Contents PT - Article <8>}, refid = {7}, title = {Impact of soluble sugar concentrations on the acquisition of freezing tolerance in accessions of \textit{Arabidopsis thaliana} with contrasting cold adaptation - evidence for a role of raffinose in cold acclimation}, volume = 27, year = 2004 }
Heyer, A.G., Raap, M., Schroeer, B., Marty, B., Willmitzer, L.: Cell wall invertase expression at the apical meristem alters floral, architectural, and reproductive traits in Arabidopsis thaliana. Plant Journal. 39, 161–169 (2004). https://doi.org/10.1111/j.1365-313X.2004.02124.x.
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@article{noauthororeditor, abstract = {Summary Resource allocation is a major determinant of plant fitness and is influenced by external as well as internal stimuli. We have investigated the effect of cell wall invertase activity on the transition from vegetative to reproductive growth, inflorescence architecture, and reproductive output, i.e. seed production, in the model plant Arabidopsis thaliana by expressing a cell wall invertase under a meristem-specific promoter. Increased cell wall invertase activity causes accelerated flowering and an increase in seed yield by nearly 30\%. This increase is caused by an elevation of the number of siliques, which results from enhanced branching of the inflorescence. On the contrary, as cytosolic enzyme, the invertase causes delayed flowering, reduced seed yield, and branching. This demonstrates that invertases not only are important in determining sink strength of storage organs but also play a role in regulating developmental processes.}, author = {Heyer, Arnd G. and Raap, Maik and Schroeer, Birgit and Marty, Bruno and Willmitzer, Lothar}, doi = {10.1111/j.1365-313X.2004.02124.x}, journal = {Plant Journal}, number = 2, pages = {161-169}, title = {Cell wall invertase expression at the apical meristem alters floral, architectural, and reproductive traits in Arabidopsis thaliana}, url = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2004.02124.x}, volume = 39, year = 2004 }
Link
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2004.02124.x
Clark, G.T., Zuther, E., Outred, H.A., McManus, M.T., Heyer, A.G.: Tissue-specific changes in remobilisation of fructan in the xerophytic tussock species Festuca novae-zelandiae in response to a water deficit. Functional Plant Biology. 31, 377 (2004). https://doi.org/10.1071/fp03230.
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@article{Clark_2004, author = {Clark, Greg T. and Zuther, Ellen and Outred, Heather A. and McManus, Michael T. and Heyer, Arnd G.}, doi = {10.1071/fp03230}, journal = {Functional Plant Biology}, number = 4, pages = 377, publisher = {{CSIRO} Publishing}, title = {Tissue-specific changes in remobilisation of fructan in the xerophytic tussock species Festuca novae-zelandiae in response to a water deficit}, url = {https://doi.org/10.1071%2Ffp03230}, volume = 31, year = 2004 }
Link
https://doi.org/10.1071%2Ffp03230
Hincha, D.K., Zuther, E., Heyer, A.G.: The preservation of liposomes by raffinose family oligosaccharides during drying is mediated by effects on fusion and lipid phase transitions. Biochimica et Biophysica Acta (BBA) - Biomembranes. 1612, 172--177 (2003). https://doi.org/10.1016/s0005-2736(03)00116-0.
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@article{Hincha_2003, author = {Hincha, Dirk K. and Zuther, Ellen and Heyer, Arnd G.}, doi = {10.1016/s0005-2736(03)00116-0}, journal = {Biochimica et Biophysica Acta ({BBA}) - Biomembranes}, month = {06}, number = 2, pages = {172--177}, publisher = {Elsevier {BV}}, title = {The preservation of liposomes by raffinose family oligosaccharides during drying is mediated by effects on fusion and lipid phase transitions}, url = {https://doi.org/10.1016%2Fs0005-2736%2803%2900116-0}, volume = 1612, year = 2003 }
Link
https://doi.org/10.1016%2Fs0005-2736%2803%2900116-0
Popova, A.V., Heyer, A.G., Hincha, D.K.: Differential destabilization of membranes by tryptophan and phenylalanine during freezing: the roles of lipid composition and membrane fusion. Biochimica et Biophysica Acta (BBA) - Biomembranes. 1561, 109--118 (2002). https://doi.org/10.1016/s0005-2736(01)00462-x.
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@article{Popova_2002, author = {Popova, Antoaneta V. and Heyer, Arnd G. and Hincha, Dirk K.}, doi = {10.1016/s0005-2736(01)00462-x}, journal = {Biochimica et Biophysica Acta ({BBA}) - Biomembranes}, month = {03}, number = 1, pages = {109--118}, publisher = {Elsevier {BV}}, title = {Differential destabilization of membranes by tryptophan and phenylalanine during freezing: the roles of lipid composition and membrane fusion}, url = {https://doi.org/10.1016%2Fs0005-2736%2801%2900462-x}, volume = 1561, year = 2002 }
Link
https://doi.org/10.1016%2Fs0005-2736%2801%2900462-x
Hincha, D.K., Zuther, E., Hellwege, E.M., Heyer, A.G.: Specific effects of fructo- and gluco-oligosaccharides in the preservation of liposomes during drying. Glycobiology. 12, 103--110 (2002). https://doi.org/10.1093/glycob/12.2.103.
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@article{hincha2002, abstract = {The fructan family of oligo- and polysaccharides is a group of molecules that have long been implicated as protective agents in the drought and freezing tolerance of many plant species. However, it has been unclear whether fructans have properties that make them better protectants for cellular structures than other sugars. We compared the effects of fructans and glucans on membrane stability during air-drying. Although glucans of increasing chain length were progressively less able to stabilize liposomes against leakage of aqueous content after rehydration, fructans showed increased protection. On the other hand, glucans became more effective in protecting liposomes against membrane fusion with increasing chain length, whereas fructans became less effective. Fourier transform infrared spectroscopy showed a reduction of the gel to liquid-crystalline phase transition temperature (Tm) of air-dried liposomes by approximately 25°C in the presence of sucrose and maltose. For the respective pentasaccharides, the reduction of Tm of the lipids was 9°C lower for samples containing fructan than for those containing glucan, indicating increased sugar–membrane interactions for the fructan compared to the glucan. A reduced interaction of the longer-chain glucans and an increased interaction of the respective fructans with the phospholipid head groups in the dry state was also indicated by dramatic differences in the phosphate asymmetric stretch region of the infrared spectrum. Collectively, our data indicate that the fructo-oligosaccharides accumulated in many plant species under stress conditions could indeed play an important role in cellular dehydration tolerance.}, author = {Hincha, Dirk K. and Zuther, Ellen and Hellwege, Elke M. and Heyer, Arnd G.}, comment = {10.1093/glycob/12.2.103}, doi = {10.1093/glycob/12.2.103}, issn = {09596658}, journal = {Glycobiology}, month = {02}, number = 2, pages = {103--110}, privnote = {10.1093/glycob/12.2.103}, title = {Specific effects of fructo- and gluco-oligosaccharides in the preservation of liposomes during drying}, url = {http://dx.doi.org/10.1093/glycob/12.2.103ER}, volume = 12, year = 2002 }
Link
http://dx.doi.org/10.1093/glycob/12.2.103ER
Oliver, A.E., Leprince, O., Wolkers, W.F., Hincha, D.K., Heyer, A.G., Crowe, J.H.: Non-Disaccharide-Based Mechanisms of Protection during Drying. Cryobiology. 43, 151--167 (2001). https://doi.org/10.1006/cryo.2001.2359.
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@article{Oliver_2001, author = {Oliver, Ann E. and Leprince, Olivier and Wolkers, Willem F. and Hincha, Dirk K. and Heyer, Arnd G. and Crowe, John H.}, doi = {10.1006/cryo.2001.2359}, journal = {Cryobiology}, month = {09}, number = 2, pages = {151--167}, publisher = {Elsevier {BV}}, title = {Non-Disaccharide-Based Mechanisms of Protection during Drying}, url = {https://doi.org/10.1006%2Fcryo.2001.2359}, volume = 43, year = 2001 }
Link
https://doi.org/10.1006%2Fcryo.2001.2359
Heyer, A.G., Wendenburg, R.: Gene Cloning and Functional Characterization by Heterologous Expression of the Fructosyltransferase of Aspergillus sydowi IAM 2544. Applied and Environmental Microbiology. 67, 363–370 (2001). https://doi.org/10.1128/AEM.67.1.363-370.2001.
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@article{heyer2001, abstract = {We have purified a fructosyltransferase from conidia of the inulin-producing fungus Aspergillus sydowi IAM 2544 and obtained peptide sequences from proteolytic fragments of the protein. With degenerated primers, we amplified a PCR fragment that was used to screen a cDNA library. The fructosyltransferase gene fromAspergillus sydowi (EMBL accession no. AJ289046) is expressed in conidia, while no expression could be detected in mycelia by Northern blot analysis of mycelial RNA. The gene encodes a protein with a calculated molecular mass of 75 kDa that is different from all fructosyltransferases in the databases. The only homology that could be detected was to the invertase of Aspergillus niger (EMBL accession no. L06844). The gene was functionally expressed inEscherichia coli, yeast, and potato plants. With protein extracts from transgenic bacteria and yeast, fructooligosaccharides could be produced in vitro. In transgenic potato plants, inulin molecules of up to 40 hexose units were synthesized in vivo. While in vitro experiments with protein extracts from conidia ofAspergillus sydowi yielded the same pattern of oligosaccharides as extracts from transformed bacteria and yeast, in vivo inulin synthesis with fungal conidia leads to the production of a high-molecular-weight polymer. }, author = {Heyer, Arnd G. and Wendenburg, Regina}, doi = {10.1128/AEM.67.1.363-370.2001}, journal = {Applied and Environmental Microbiology}, pages = {363-370}, series = 1, title = {Gene Cloning and Functional Characterization by Heterologous Expression of the Fructosyltransferase of Aspergillus sydowi IAM 2544}, url = {https://aem.asm.org/content/aem/67/1/363.full.pdf}, volume = 67, year = 2001 }
Link
https://aem.asm.org/content/aem/67/1/363.full.pdf
Wolff, D., Czapla, S., Heyer, A.G., Radosta, S., Mischnick, P., Springer, J.: Globular shape of high molar mass inulin revealed by static light scattering and viscometry. Polymer. 41, 8009--8016 (2000). https://doi.org/10.1016/s0032-3861(00)00168-3.
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@article{Wolff_2000, author = {Wolff, D. and Czapla, S. and Heyer, A.G. and Radosta, S. and Mischnick, P. and Springer, J.}, doi = {10.1016/s0032-3861(00)00168-3}, journal = {Polymer}, month = {10}, number = 22, pages = {8009--8016}, publisher = {Elsevier {BV}}, title = {Globular shape of high molar mass inulin revealed by static light scattering and viscometry}, url = {https://doi.org/10.1016%2Fs0032-3861%2800%2900168-3}, volume = 41, year = 2000 }
Link
https://doi.org/10.1016%2Fs0032-3861%2800%2900168-3
Hincha, D.K., Hellwege, E.M., Heyer, A.G., Crowe, J.H.: Plant fructans stabilize phosphatidylcholine liposomes during freeze-drying. European Journal of Biochemistry. 267, 535–540 (2000). https://doi.org/10.1046/j.1432-1327.2000.01028.x.
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@article{hincha2000, abstract = {Fructans have been implicated as protective agents in the drought and freezing tolerance of many plant species. A direct proof of their ability to stabilize biological structures under stress conditions, however, is still lacking. Here we show that inulins (linear fructose polymers) isolated from chicory roots and dahlia tubers stabilize egg phosphatidylcholine large unilamellar vesicles during freeze-drying, while another polysaccharide, hydroxyethyl starch, was completely ineffective. Liposome stability was assessed after rehydration by measuring retention of the soluble fluorescent dye carboxyfluorescein and bilayer fusion. Inulin was an especially effective stabilizer in combination with glucose. Analysis by HPLC showed that the commercial inulin preparations used in our study contained no low molecular mass sugars that could be responsible for the observed stabilizing effect of the fructans. Fourier transform infrared spectroscopy showed a reduction of the gel to liquid-crystalline phase transition temperature of dry egg PtdCho by more than 20 °C in the presence of inulin. A direct interaction of inulin with the phospholipid in the dry state was also indicated by dramatic differences in the phosphate asymmetric stretch region of the infrared spectrum between samples with and without the polysaccharide. }, author = {Hincha, Dirk K. and Hellwege, Elke M. and Heyer, Arnd G. and Crowe, John H.}, doi = {10.1046/j.1432-1327.2000.01028.x}, journal = {European Journal of Biochemistry}, pages = {535-540}, series = 2, title = {Plant fructans stabilize phosphatidylcholine liposomes during freeze-drying}, url = {https://febs.onlinelibrary.wiley.com/doi/abs/10.1046/j.1432-1327.2000.01028.x}, volume = 267, year = 2000 }
Link
https://febs.onlinelibrary.wiley.com/doi/abs/10.1046/j.1432-1327.2000.01028.x
Hellwege, E.M., Czapla, S., Jahnke, A., Willmitzer, L., Heyer, A.G.: Transgenic potato (Solanum tuberosum) tubers synthesize the full spectrum of inulin molecules naturally occurring in globe artichoke (Cynara scolymus) roots. Proceedings of the National Academy of Sciences. 97, 8699–8704 (2000). https://doi.org/10.1073/pnas.150043797.
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@article{hellwege2000, abstract = {The ability to synthesize high molecular weight inulin was transferred to potato plants via constitutive expression of the 1-SST (sucrose:sucrose 1-fructosyltransferase) and the 1-FFT (fructan: fructan 1-fructosyltransferase) genes of globe artichoke (Cynara scolymus). The fructan pattern of tubers from transgenic potato plants represents the full spectrum of inulin molecules present in artichoke roots as shown by high-performance anion exchange chromatography, as well as size exclusion chromatography. These results demonstrate in planta that the enzymes sucrose:sucrose 1-fructosyltransferase and fructan:fructan 1-fructosyltransferase are sufficient to synthesize inulin molecules of all chain lengths naturally occurring in a given plant species. Inulin made up 5% of the dry weight of transgenic tubers, and a low level of fructan production also was observed in fully expanded leaves. Although inulin accumulation did not influence the sucrose concentration in leaves or tubers, a reduction in starch content occurred in transgenic tubers, indicating that inulin synthesis did not increase the storage capacity of the tubers. 1-SST,sucrose:sucrose 1-fructosyltransferase;1-FFT,fructan:fructan 1-fructosyltransferase;HPAEC,high-performance anion exchange chromatography;SEC,size exclusion chromatography;DP,degree of polymerization }, author = {Hellwege, Elke M. and Czapla, Sylvia and Jahnke, Anuschka and Willmitzer, Lothar and Heyer, Arnd G.}, doi = {10.1073/pnas.150043797}, journal = {Proceedings of the National Academy of Sciences}, pages = {8699-8704}, series = 15, title = {Transgenic potato (Solanum tuberosum) tubers synthesize the full spectrum of inulin molecules naturally occurring in globe artichoke (Cynara scolymus) roots}, url = {http://www.pnas.org/content/pnas/97/15/8699.full.pdf}, volume = 97, year = 2000 }
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http://www.pnas.org/content/pnas/97/15/8699.full.pdf

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