Cyclic electron flow around PSI functions in the photoinhibited rice leaves

Satoshi Kubo, Takehiro Masumura, Yuhi Saito, Hiroshi Fukayama, Yuji Suzuki, Toshio Sugimoto, Amane Makino, Katsumi Amako, Chikahiro Miyake

    Research output: Contribution to journalArticlepeer-review

    4 Citations (Scopus)


    We investigated the regulation mechanism of cyclic electron flow around photosystem I (CEF-PSI) in the rice leaves which suffered from photosystem II (PSII) photoinhibition. High-light (HL) treatment [2000 μmol photon m-2 s-1 at 0% carbon dioxide (CO2), 2% oxygen (O2) and 25°C] of rice leaves decreased both the maximum quantum efficiency of PSII (Fv/Fm) and the light-dependent O2-evolution rate [V(O2)]. High-light treatment did not affect the relative electron flux in PSI [Φ(PSI) × PFD]. In non-treated leaves, increasing in the photon flux density (PFD) enhanced V(O2), Φ(PSI) × PFD and the ratio of oxidized P700 to total P700 [(P700+)/(P700)total]. Φ(PSI) × PFD continued to increase even after the saturation of V(O2) against PFD. These results suggested that the electrons not used for the major electron sink, photosynthetic carbon reduction-cycle, did turnover in PSI, that is, CEF-PSI functioned at a higher PFD. High-light treatments did not affect the activity of CEF-PSI and increased (P700+)/(P700)total in the lower PFDs, compared to non-treated leaves. The activity of CEF-PSI depends on the amount of oxidized PQ. Photoinhibition of PSII suppressed electron influx from PSII to photosynthetic linear electron transport. The enhanced (P700+)/(P700)total suggested the increase in the ratio of oxidized plastoquinone (PQ) to total PQ, which supported the activity of CEF-PSI in the photoinhibited leaves.

    Original languageEnglish
    Pages (from-to)105-113
    Number of pages9
    JournalSoil Science and Plant Nutrition
    Issue number1
    Publication statusPublished - 2011 Feb


    • Cyclic electron flow around PSI
    • P700
    • PSI
    • Photoinhibition
    • Rice

    ASJC Scopus subject areas

    • Soil Science
    • Plant Science


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