High-irradiance stress and photochemical activities of photosystems 1 and 2 in vivo

K. Veeranjaneyulu, M. Charland, R. M. Leblanc

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


High-irradiance (HI) stress induced changes in the photosynthetic energy storage (ES) of photosystems 1 (ES(PS1)) and 2 (ES(PS2)) were studied with 650 nm modulated radiation in intact sugar maple (Acer saccharum Marsh.) leaves. HI-treatment (420 W m-2, 1 h) caused an inhibition of about 40 % in ES(PS2) and an enhancement of about 60 % in ES(PS1). The rate of PS1 cyclic electron transport, measured with 705 nm modulated radiation, also increased in HI-treated leaves. There was a clear state 1-state 2 transition in HI-treated leaves. ES(PS1) increased significantly and ES(PS2) decreased drastically in leaves preadapted to state 1 after HI (600 W m-2, 30 min) treatment. Thus, the increase in PS1 activity observed immediately after HI-treatment in leaves preadapted to state 1 can be due to the coupling of LHC2 to PS1 during the HI-treatment. Further, the dissociation of LHC2 from PS2 during the HI-treatment resulted in apparently (about 15%) greater inhibition than the 'true' inhibition of PS2 activity. The presence of LHC2 with PS2 (state 1) at the time of HI-treatment caused no additional damage to PS2 or its coupling to PSI offered no apparent protection to the photosynthetic apparatus.

Original languageEnglish (US)
Pages (from-to)177-190
Number of pages14
Issue number2
StatePublished - 1998


  • Acer saccharum
  • Light-harvesting complex 2
  • Photoacoustic spectroscopy

ASJC Scopus subject areas

  • Plant Science


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