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Proc Natl Acad Sci U S A. 2015 Apr 28;112(17):5539-44. doi: 10.1073/pnas.1418223112. Epub 2015 Apr 13.

Activation of cyclic electron flow by hydrogen peroxide in vivo.

Author information

  • 1Plant Research Laboratory and Departments of Plant Biology and.
  • 2School of Molecular Biosciences and Institute for Biological Chemistry, Washington State University, Pullman, WA 99164; and.
  • 3Plant Research Laboratory and.
  • 4Plant Research Laboratory and Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824;
  • 5Institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich-Heine-Universität, Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany.
  • 6Plant Research Laboratory and Departments of Plant Biology and Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824;


Cyclic electron flow (CEF) around photosystem I is thought to balance the ATP/NADPH energy budget of photosynthesis, requiring that its rate be finely regulated. The mechanisms of this regulation are not well understood. We observed that mutants that exhibited constitutively high rates of CEF also showed elevated production of H2O2. We thus tested the hypothesis that CEF can be activated by H2O2 in vivo. CEF was strongly increased by H2O2 both by infiltration or in situ production by chloroplast-localized glycolate oxidase, implying that H2O2 can activate CEF either directly by redox modulation of key enzymes, or indirectly by affecting other photosynthetic processes. CEF appeared with a half time of about 20 min after exposure to H2O2, suggesting activation of previously expressed CEF-related machinery. H2O2-dependent CEF was not sensitive to antimycin A or loss of PGR5, indicating that increased CEF probably does not involve the PGR5-PGRL1 associated pathway. In contrast, the rise in CEF was not observed in a mutant deficient in the chloroplast NADPH:PQ reductase (NDH), supporting the involvement of this complex in CEF activated by H2O2. We propose that H2O2 is a missing link between environmental stress, metabolism, and redox regulation of CEF in higher plants.


cyclic electron flow; hydrogen peroxide; photosynthesis; reactive oxygen species; stress

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