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Superoxide anion radicals generated by methylviologen in photosystem I damage photosystem II
Author(s) -
KriegerLiszkay Anja,
Kós Péter B.,
Hideg Éva
Publication year - 2011
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2010.01416.x
Subject(s) - photosystem ii , superoxide , chemistry , photochemistry , photosystem i , p700 , thylakoid , reactive oxygen species , radical , photosynthesis , photosynthetic reaction centre , electron transfer , biochemistry , chloroplast , enzyme , gene
The effect of superoxide anion radicals on the photosynthetic electron transport chain was studied in leaves and isolated thylakoids from tobacco. Superoxide was generated by methylviologen (MV) in the light at the acceptor side of photosystem I (PSI). In isolated thylakoids, the largest damage was observed at the level of the water‐splitting activity in photosystem II (PSII), whereas PSI was hardly affected at the light intensities used. Addition of reactive oxygen scavengers protected PSII against damage. In leaves in the presence of MV, the quantum yield of PSII decreased during illumination whereas the size of the P 700 signal remained constant. There was no D1 protein loss in leaves illuminated in the presence of MV and lincomycin, but a modification to a slightly higher molecular mass was observed. These data show that PSII is more sensitive to superoxide or superoxide‐derived reactive oxygen species (ROS) than PSI. In our experiments, this susceptibility was not because of any action of the ROS on the translation of the D1 protein or on the repair cycle of photosystem.