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@ARTICLE{vanDongen:35010,
      author       = {van Dongen, J. T. and Roeb, G. W. and Dautzenberg, M. and
                      Fröhlich, A. and Vigeolas, H. and Minchin, P. R. and
                      Geigenberger, P.},
      title        = {{P}hloem import and storage metabolism are highly
                      coordinated by the low oxygen concentrations within
                      developing wheat seeds},
      journal      = {Plant physiology},
      volume       = {135},
      issn         = {0032-0889},
      address      = {Rockville, Md.: Soc.},
      publisher    = {JSTOR},
      reportid     = {PreJuSER-35010},
      pages        = {1809 - 1821},
      year         = {2004},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {We studied the influence of the internal oxygen
                      concentration in seeds of wheat (Triticum aestivum) on
                      storage metabolism and its relation to phloem import of
                      nutrients. Wheat seeds that were developing at ambient
                      oxygen $(21\%)$ were found to be hypoxic $(2.1\%).$ Altering
                      the oxygen supply by decreasing or increasing the external
                      oxygen concentration induced parallel changes in the
                      internal oxygen tension. However, the decrease in internal
                      concentration was proportionally less than the reduction in
                      external oxygen. This indicates that decreasing the oxygen
                      supply induces short-term adaptive responses to reduce
                      oxygen consumption of the seeds. When external oxygen was
                      decreased to $8\%,$ internal oxygen decreased to
                      approximately $0.5\%$ leading to a decrease in energy
                      production via respiration. Conversely, increasing the
                      external oxygen concentration above ambient levels increased
                      the oxygen content as well as the energy status of the
                      seeds, indicating that under normal conditions the oxygen
                      supply is strongly limiting for energy metabolism in
                      developing wheat seeds. The intermediate metabolites of seed
                      storage metabolism were not substantially affected when
                      oxygen was either increased or decreased. However, at
                      subambient external oxygen concentrations $(8\%)$ the
                      metabolic flux of carbon into starch and protein, measured
                      by injecting (14)C-Suc into the seeds, was reduced by $17\%$
                      and $32\%,$ respectively, whereas no significant effect was
                      observed at superambient $(40\%)$ oxygen. The observed
                      decrease in biosynthetic fluxes to storage compounds is
                      suggested to be part of an adaptive response to reduce
                      energy consumption preventing excessive oxygen consumption
                      when oxygen supply is limited. Phloem transport toward ears
                      exposed to low $(8\%)$ oxygen was significantly reduced
                      within 1 h, whereas exposing ears to elevated oxygen
                      $(40\%)$ had no significant effect. This contrasts with the
                      situation where the distribution of assimilates has been
                      modified by removing the lower source leaves from the plant,
                      resulting in less assimilates transported to the ear in
                      favor of transport to the lower parts of the plant. Under
                      these conditions, with two strongly competing sinks,
                      elevated oxygen $(40\%)$ did lead to a strong increase in
                      phloem transport to the ear. The results show that sink
                      metabolism is affected by the prevailing low oxygen
                      concentrations in developing wheat seeds, determining the
                      import rate of assimilates via the phloem.},
      keywords     = {Cell Hypoxia: drug effects / Energy Metabolism / Kinetics /
                      Nucleotides: metabolism / Oxygen: metabolism / Oxygen:
                      pharmacology / Plant Structures: drug effects / Plant
                      Structures: metabolism / Seeds: metabolism / Triticum: drug
                      effects / Triticum: metabolism / Nucleotides (NLM Chemicals)
                      / Oxygen (NLM Chemicals) / J (WoSType)},
      cin          = {ICG-III},
      ddc          = {580},
      cid          = {I:(DE-Juel1)VDB49},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      shelfmark    = {Plant Sciences},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:15247408},
      pmc          = {pmc:PMC519092},
      UT           = {WOS:000222692700058},
      doi          = {10.1104/pp.104.040980},
      url          = {https://juser.fz-juelich.de/record/35010},
}