OXYGEN DEPENDENCE OF PHOTOINHIBITION AT LOW-TEMPERATURE IN INTACT PROTOPLASTS OF VALERIANELLA-LOCUSTA L

KJ VANWIJK, GH KRAUSE*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    20 Citations (Scopus)

    Abstract

    Photoinhibition of photosynthesis in vivo is shown to be considerably promoted by O2 under circumstances where energy turnover by photorespiration and photosynthetic carbon metabolism are low. Intact protoplasts of Valerianella locusta L. were photoinhibited by 30 min irradiation with 3000-mu-mol photons.m-2.s-1 at 4-degrees-C in saturating [CO2] at different oxygen concentrations, corresponding to 2-40% O2 in air. The photoinhibition of light-limited CO2-dependent photosynthetic O2 evolution increased with increasing oxygen concentration. The uncoupled photochemical activity of photosystem II, measured in the presence of the electron acceptor 1,4-benzoquinone, and maximum variable fluorescence, F(V), were strongly affected and this inhibition was closely correlated to the O2 concentration. The effect of O2 did not saturate at the highest concentrations applied. An increase in photoinhibitory fluorescence quenching with [O2], although less pronounced than in protoplasts, was also observed with intact leaves irradiated at 4-degrees-C in air. Initial fluorescence, F(O), was slightly (about 10%) increased by the inhibitory treatments but not influenced by [O2]. A long-term cold acclimation of the plants did not substantially alter the O2-sensitivity of the protoplasts under the high-light treatment. From these experiments we conclude that oxygen is involved in the photoinactivation of photosystem II by excess light in vivo.

    Original languageEnglish
    Pages (from-to)135-142
    Number of pages8
    JournalPlanta
    Volume186
    Issue number1
    Publication statusPublished - 1991

    Keywords

    • COLD ACCLIMATION
    • PHOTOINHIBITION OF PHOTOSYNTHESIS
    • PHOTOSYSTEM-II
    • PROTOPLAST
    • TEMPERATURE, LOW
    • VALERIANELLA
    • PHOTOSYSTEM-II PHOTOINACTIVATION
    • CHILLING-ENHANCED PHOTOOXIDATION
    • ACCLIMATED SPINACH LEAVES
    • CHLOROPHYLL FLUORESCENCE
    • PHOTOSYNTHETIC REACTIONS
    • GLUTATHIONE-REDUCTASE
    • LIGHT
    • CHLOROPLASTS
    • INHIBITION
    • MECHANISM

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