guest ::
| Home > Publications database > Deficiency and toxicity of micronutrients and related elements in plants |
| Home > Publications database > Deficiency and toxicity of micronutrients and related elements in plants |
| Conference Presentation | PUBDB-2015-00768 |
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.
|
The record appears in these collections: |
