title: Superoxide and Singlet Oxygen Produced within the Thylakoid Membranes Both Cause Photosystem I Photoinhibition.
abstract: Photosystem I (PSI) photoinhibition suppresses plant photosynthesis and growth. However, the mechanism underlying PSI photoinhibition has not been fully clarified. In this study, in order to investigate the mechanism of PSI photoinhibition in higher plants, we applied repetitive short-pulse (rSP) illumination, which causes PSI-specific photoinhibition in chloroplasts isolated from spinach leaves. We found that rSP treatment caused PSI photoinhibition, but not PSII photoinhibition in isolated chloroplasts in the presence of O2 However, chloroplastic superoxide dismutase and ascorbate peroxidase activities failed to protect PSI from its photoinhibition. Importantly, PSI photoinhibition was largely alleviated in the presence of methyl viologen, which stimulates the production of reactive oxygen species (ROS) at the stromal region by accepting electrons from PSI, even under the conditions where CuZn-superoxide dismutase and ascorbate peroxidase activities were inactivated by KCN. These results suggest that the ROS production site, but not the ROS production rate, is critical for PSI photoinhibition. Furthermore, we found that not only superoxide (O2 (-)) but also singlet oxygen ((1)O2) is involved in PSI photoinhibition induced by rSP treatment. From these results, we suggest that PSI photoinhibition is caused by both O2 (-) and (1)O2 produced within the thylakoid membranes when electron carriers in PSI become highly reduced. Here, we show, to our knowledge, new insight into the PSI photoinhibition in higher plants.
authors.affiliation: Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan (D.T., S.T., M.H., T.S., C.M.); andCore Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan (C.M.).
authors.forename: Daisuke
authors.identifier: 0000-0003-0880-5877
authors.initials: D
authors.lastname: Takagi
authors.affiliation: Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan (D.T., S.T., M.H., T.S., C.M.); andCore Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan (C.M.).
authors.forename: Shigeo
authors.initials: S
authors.lastname: Takumi
authors.affiliation: Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan (D.T., S.T., M.H., T.S., C.M.); andCore Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan (C.M.).
authors.forename: Masaki
authors.initials: M
authors.lastname: Hashiguchi
authors.affiliation: Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan (D.T., S.T., M.H., T.S., C.M.); andCore Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan (C.M.).
authors.forename: Takehiro
authors.initials: T
authors.lastname: Sejima
authors.affiliation: Department of Biological and Environmental Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan (D.T., S.T., M.H., T.S., C.M.); andCore Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan (C.M.) cmiyake@hawk.kobe.u-ac.jp.
authors.forename: Chikahiro
authors.identifier: 0000-0002-2426-2377
authors.initials: C
authors.lastname: Miyake
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D009550:Nigericin / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology; D045331:Photosystem I Protein Complex / Q000378:metabolism* / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*; D018724:Spinacia oleracea / Q000187:drug effects / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D007476:Ionophores; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D002734:Chlorophyll; D026082:Singlet Oxygen; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase; D010269:Paraquat; D009550:Nigericin; D010100:Oxygen