Singlet oxygen production in herbicide-treated photosystem II

FEBS Lett. 2002 Dec 18;532(3):407-10. doi: 10.1016/s0014-5793(02)03724-9.


Photo-generated reactive oxygen species in herbicide-treated photosystem II were investigated by spin-trapping. While the production of .OH and O2-* was herbicide-independent, 1O2 with a phenolic was twice that with a urea herbicide. This correlates with the reported influence of these herbicides on the redox properties of the semiquinone QA-* and fits with the hypothesis that 1O2 is produced by charge recombination reactions that are stimulated by herbicide binding and modulated by the nature of the herbicide. When phenolic herbicides are bound, charge recombination at the level of P+*Pheo-* is thermodynamically favoured forming a chlorophyll triplet and hence 1O2. With urea herbicides this pathway is less favourable.

MeSH terms

  • Binding Sites
  • Cell Membrane / metabolism
  • Chlorophyll / metabolism
  • Diuron / pharmacology
  • Electron Spin Resonance Spectroscopy
  • Herbicides / pharmacology*
  • Light
  • Light-Harvesting Protein Complexes
  • Nitriles / pharmacology
  • Oxidation-Reduction
  • Oxygen / metabolism*
  • Photosynthetic Reaction Center Complex Proteins / drug effects*
  • Photosystem II Protein Complex
  • Reactive Oxygen Species*
  • Spinacia oleracea
  • Urea / pharmacology


  • Herbicides
  • Light-Harvesting Protein Complexes
  • Nitriles
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem II Protein Complex
  • Reactive Oxygen Species
  • Chlorophyll
  • Urea
  • Diuron
  • bromoxynil
  • Oxygen