Intrinsic fluctuations in transpiration induce photorespiration to oxidize p700 in photosystem I

Riu Furutani, Amane Makino, Yuij Suzuki, Shinya Wada, Ginga Shimakawa, Chikahiro Miyake

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)


    Upon exposure to environmental stress, the primary electron donor in photosystem I (PSI), P700, is oxidized to suppress the production of reactive oxygen species that could oxidatively inactivate the function of PSI. The illumination of rice leaves with actinic light induces intrinsic fluctuations in the opening and closing of stomata, causing the net CO2 assimilation rate to fluctuate. We examined the effects of these intrinsic fluctuations on electron transport reactions. Under atmospheric O2 conditions (21 kPa), the effective quantum yield of photosystem II (PSII) (Y(II)) remained relatively high while the net CO2 assimilation rate fluctuated, which indicates the function of alternative electron flow. By contrast, under low O2 conditions (2 kPa), Y(II) fluctuated. These results suggest that photorespiration primarily drove the alternative electron flow. Photorespiration maintained the oxidation level of ferredoxin (Fd) throughout the fluctuation of the net CO2 assimilation rate. Moreover, the relative activity of photorespiration was correlated with both the oxidation level of P700 and the magnitude of the proton gradient across the thylakoid membrane in 21 kPa O2 conditions. These results show that photorespiration oxidized P700 by stimulating the proton gradient formation when CO2 assimilation was suppressed by stomatal closure.

    Original languageEnglish
    Article number1761
    Pages (from-to)1-16
    Number of pages16
    Issue number12
    Publication statusPublished - 2020 Dec


    • P700
    • Photorespiration
    • Photosystem I
    • RISE
    • ∆pH

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Ecology
    • Plant Science


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