Journal of Photosciences

Decrease of Photochemical Efficiency Induced by Methyl Viologen in Rice (Oryza sativa L.) Leaves is Partly due to the Down-Regulation of PSII

Volume 9(2002), 65-70 page

저자: Jin-Hong Kim and Choon-Hwan Lee

   9-3-65.pdf (119.8K)

Keywords: methyl viologen  chlorophyll fluorescence  down-regulation of PSII  reversible photoinactivation  dark-recovery  photosynthesis


In the rice leaves treated with methyl viologen (MV), the photochemical efficiency of PSII (or Fv/Fm) was significantly decreased, and significant portion of the photoinactivation process was reversible during the dark-recovery.
The dark-reactivation process was relatively slow, reaching its plateau after 2-2.5 h of dark incubation.
The damaged portion of functional PSII was 13%, based on the value of 1/F0-1/Fm after this dark-recovery period.
The reversible photoinactivation process of PSII function in the MV-treated leaves consisted of a xanthophyll cycle-dependent development of NPQ and a xanthophyll cycle-independent process.
The latter process was reversible in the presence of nigericin.
As well as the increase in the values of Chl fluorescence parameters, the epoxidation process during the darkrecovery after the MV-induced photooxidation was very slow.
These results suggest that the photooxidative effect of MV is partly protected by the down-regulation of PSII before inducing physical damages in core proteins of PSII.