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@INPROCEEDINGS{Kuepper:206254,
      author       = {Kuepper, Hendrik},
      title        = {{D}eficiency and toxicity of micronutrients and related
                      elements in plants},
      reportid     = {PUBDB-2015-00768},
      year         = {2014},
      abstract     = {Many heavy metals are essential trace elements, but
                      elevated concentrations are toxic. One central focus of our
                      research is on the response of higher plants and algae to
                      trace metals in terms of uptake, transport, sequestration,
                      complexation, deficiency, toxicity and detoxification. These
                      processes are decisive factors in plant nutrition because of
                      vastly different (due to natural and anthropogenic
                      influence) trace metal concentrations in various habitats,
                      ranging from deficient to toxic levels. In contrast to
                      earlier studies in the field, we use conditions that allowed
                      us to work also in the sub-nanomolar range and with a
                      simulation of natural light- and temperature cycles. Thus,
                      with the submerged water plant Ceratophyllum demersum as a
                      model, we could show that heavy metal(loid) (As, Cd, Cr, Cu,
                      Ni) concentrations that were previously considered as not
                      having any effect actually have a strong impact on the
                      plants, and with a different sequence of events than
                      observed at very high concentrations. We used a combination
                      of various biophysical and biochemical methods for
                      measurements in vivo (e.g. photosynthesis biophysics,
                      formation of reactive oxygen species, metal transport), in
                      situ (e.g. quantitative (sub)cellular distribution and
                      speciation of metals, mRNA levels) as well as on isolated
                      proteins (for identification and characterisation of
                      metalloproteins). For example, using metalloproteomics via
                      native gels of protein extracts from plants that had been
                      treated with heavy metals we are investigating the
                      physiological and toxic binding of heavy metals to proteins.
                      Analysis of pigments showed heavy metal-induced changes
                      already at very low concentrations; this was reflected also
                      by specific changes in biophysics of photosynthesis (e.g.
                      spectral changes in non-photochemical quenching). As a
                      result of the changes already mentioned, starch metabolism
                      as well as production of reactive oxygen species were
                      influenced by such sublethal concentrations of heavy metals
                      and the metalloid arsenic in C. demersum. Our work in the
                      sub-nanomolar range further showed that C. demersum stopped
                      growth unless Cr(III) as Cr3+ or Cr(VI) as CrO42- became
                      available, as extrapolated from the growth decrease towards
                      the lowest achievable Cr (0.17 nM). This was a surprise
                      because Cr is not regarded as an essential nutrient for
                      plants. Chromium deficiency was furthermore found, although
                      not at severe likely due to lower demands comparable to the
                      lowest achievable Cr concentration, in the crop plants
                      Glycine soja (soybean) and Triticum aestivum (wheat). We
                      isolated several proteins that bind Cr with high affinity,
                      and are currently characterizing them.},
      month         = {Sep},
      date          = {2014-09-10},
      organization  = {Plant Nutrition 2014, Halle (Germany),
                       10 Sep 2014 - 12 Sep 2014},
      cin          = {DOOR},
      cid          = {I:(DE-H253)HAS-User-20120731},
      pnm          = {DORIS Beamline L (POF2-54G13) / PETRA Beamline P06
                      (POF2-54G14) / FS-Proposal: I-20120397 (I-20120397) /
                      FS-Proposal: I-20110682 (I-20110682)},
      pid          = {G:(DE-H253)POF2-L-20130405 / G:(DE-H253)POF2-P06-20130405 /
                      G:(DE-H253)I-20120397 / G:(DE-H253)I-20110682},
      experiment   = {EXP:(DE-H253)D-L-20150101 / EXP:(DE-H253)P-P06-20150101},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://bib-pubdb1.desy.de/record/206254},
}