The role of inactive photosystem-II-mediated quenching in a last-ditch community defence against high light stress in vivo

Soon Chow Wah, Hae Youn Lee, Youn Il Park, Yong Mok Park, Yong Nam Hong, Jan M. Anderson, B. Andersson, I. Vass, S. Santabarbara

Research output: Contribution to journalArticle

33 Citations (Scopus)


Photoinactivation of photosystem II (PSII), the light-induced loss of ability to evolve oxygen, is an inevitable event during normal photosynthesis, exacerbated by saturating light but counteracted by repair via new protein synthesis. The photoinactivation of PSII is dependent on the dosage of light: in the absence of repair, typically one PSII is photoinactivated per 107 photons, although the exact quantum yield of photoinactivation is modulated by a number of factors, and decreases as fewer active PSII targets are available. PSII complexes initially appear to be photoinactivated independently; however, when less than 30% functional PSII complexes remain, they seem to be protected by strongly dissipative PSII reaction centres in several plant species examined so far, a mechanism which we term 'inactive PSII-mediated quenching'. This mechanism appears to require a pH gradient across the photosynthetic membrane for its optimal operation. The residual fraction of functional PSII complexes may, in turn, aid in the recovery of photoinactivated PSII complexes when conditions become less severe. This mechanism may be important for the photosynthetic apparatus in extreme environments such as those experienced by overwintering evergreen plants, desert plants exposed to drought and full sunlight and shade plants in sustained sunlight.

Original languageEnglish
Pages (from-to)1441-1450
Number of pages10
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Issue number1426
Publication statusPublished - Oct 29 2002



  • Photoinactivation
  • Photoinhibition
  • Photoprotection
  • Photosystem II
  • Photosystem II reaction-centre quenching

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this