Physiological Functions of Cyclic Electron Transport Around Photosystem I in Sustaining Photosynthesis and Plant Growth

Annu Rev Plant Biol. 2016 Apr 29;67:81-106. doi: 10.1146/annurev-arplant-043015-112002. Epub 2016 Feb 24.


The light reactions in photosynthesis drive both linear and cyclic electron transport around photosystem I (PSI). Linear electron transport generates both ATP and NADPH, whereas PSI cyclic electron transport produces ATP without producing NADPH. PSI cyclic electron transport is thought to be essential for balancing the ATP/NADPH production ratio and for protecting both photosystems from damage caused by stromal overreduction. Two distinct pathways of cyclic electron transport have been proposed in angiosperms: a major pathway that depends on the PROTON GRADIENT REGULATION 5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE 1 (PGRL1) proteins, which are the target site of antimycin A, and a minor pathway mediated by the chloroplast NADH dehydrogenase-like (NDH) complex. Recently, the regulation of PSI cyclic electron transport has been recognized as essential for photosynthesis and plant growth. In this review, we summarize the possible functions and importance of the two pathways of PSI cyclic electron transport.

Keywords: NADH dehydrogenase–like complex; NDH complex; PGR5; PGRL1; cyclic electron transport; photoprotection; photosynthesis.

Publication types

  • Review

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Arabidopsis / metabolism
  • Arabidopsis / physiology
  • Arabidopsis Proteins / metabolism*
  • Chloroplasts / metabolism
  • Electron Transport*
  • Magnoliopsida / metabolism
  • Magnoliopsida / physiology*
  • Membrane Proteins / metabolism*
  • NADP / metabolism
  • Photosynthesis / physiology*
  • Photosynthetic Reaction Center Complex Proteins / metabolism
  • Photosystem I Protein Complex / metabolism*
  • Plant Development / physiology*
  • Plant Proteins / metabolism*


  • Arabidopsis Proteins
  • Membrane Proteins
  • PGR5 protein, Arabidopsis
  • PGRL1 protein, Arabidopsis
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • Plant Proteins
  • NADP
  • Adenosine Triphosphate