Cadmium toxicity investigated at the physiological and biophysical levels under environmentally relevant conditions using the aquatic model plant Ceratophyllum demersum
Language English Country England, Great Britain Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
26840406
DOI
10.1111/nph.13840
Knihovny.cz E-resources
- Keywords
- Cadmium (Cd), Ceratophyllum demersum, environmentally relevant, light-harvesting complexes (LHCs), macrophyte, toxic metals, toxicity,
- MeSH
- Photosynthesis * MeSH
- Photosystem II Protein Complex metabolism MeSH
- Cadmium toxicity MeSH
- Magnoliopsida drug effects physiology radiation effects MeSH
- Hydrogen Peroxide metabolism MeSH
- Reactive Oxygen Species metabolism MeSH
- Superoxides metabolism MeSH
- Light MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Photosystem II Protein Complex MeSH
- Cadmium MeSH
- Hydrogen Peroxide MeSH
- Reactive Oxygen Species MeSH
- Superoxides MeSH
Cadmium (Cd) is an important environmental pollutant and is poisonous to most organisms. We aimed to unravel the mechanisms of Cd toxicity in the model water plant Ceratophyllum demersum exposed to low (nM) concentrations of Cd as are present in nature. Experiments were conducted under environmentally relevant conditions, including nature-like light and temperature cycles, and a low biomass to water ratio. We measured chlorophyll (Chl) fluorescence kinetics, oxygen exchange, the concentrations of reactive oxygen species and pigments, metal binding to proteins, and the accumulation of starch and metals. The inhibition threshold concentration for most parameters was 20 nM. Below this concentration, hardly any stress symptoms were observed. The first site of inhibition was photosynthetic light reactions (the maximal quantum yield of photosystem II (PSII) reaction centre measured as Fv /Fm , light-acclimated PSII activity ΦPSII , and total Chl). Trimers of the PSII light-harvesting complexes (LHCIIs) decreased more than LHC monomers and detection of Cd in the monomers suggested replacement of magnesium (Mg) by Cd in the Chl molecules. As a consequence of dysfunctional photosynthesis and energy dissipation, reactive oxygen species (superoxide and hydrogen peroxide) appeared. Cadmium had negative effects on macrophytes at much lower concentrations than reported previously, emphasizing the importance of studies applying environmentally relevant conditions. A chain of inhibition events could be established.
Department of Biology University of Konstanz Konstanz D 78457 Germany
Department of Chemistry The University of Chicago GCIS E 319A 929 E 57th St Chicago IL 60637 USA
Institute of Geology of the CAS Rozvojová 269 Praha 6 Lysolaje CZ 16500 Czech Republic
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