Temperature/light dependent development of selective resistance to photoinhibition of photosystem I

FEBS Letters

Gray, G.R¹  Morgan, R.M³  Velitchkova, M.Y²  Huner, N.P.A³  Ivanov, A.G³ 

[1] MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824-1312, USA;Institute of Biophysics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria;Department of Plant Sciences, University of Western Ontario, 1151 Richmond Street N., London, Ontario, N6H 5B7, Canada

关键词: Photosystem I;    Photoinhibition;    P700;    Intersystem electron pool;    Excitation pressure;    Low temperature;    EPR;    electron paramagnetic resonance;    Fm;    maximal chlorophyll fluorescence with all PSII reaction centers closed in dark-adapted state;    Fo;    minimal fluorescence with all PSII reaction centers open in dark-adapted state;    Fv;    variable fluorescence (Fm−Fo);    PsaA/PsaB;    heterodimer of PSI reaction center;    PSI;    PSII;    photosystem I and photosystem II;    respectively;    P700;    reaction center pigment of PSI;    P700+;    oxidized form of the reaction center pigment of PSI;    qP;    photochemical quenching of chlorophyll fluorescence;   

DOI  :  10.1016/S0014-5793(98)00681-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Exposure of winter rye leaves grown at 20°C and an irradiance of either 50 or 250 μmol m⁻² s⁻¹ to high light stress (1600 μmol m⁻² s⁻¹, 4 h) at 5°C resulted in photoinhibition of PSI measured in vivo as a 34% and 31% decrease in ΔA₈₂₀/A₈₂₀ (P700⁺). The same effect was registered in plants grown at 5°C and 50 μmol m⁻² s⁻¹. This was accompanied by a parallel degradation of the PsaA/PsaB heterodimer, increase of the intersystem e⁻ pool size as well as inhibition of PSII photochemistry measured as F_v/F_m. Surprisingly, plants acclimated to high light (800 μmol m⁻² s⁻¹) or to 5°C and moderate light (250 μmol m⁻² s⁻¹) were fully resistant to photoinhibition of PSI and did not exhibit any measurable changes at the level of PSI heterodimer abundance and intersystem e⁻ pool size, although PSII photochemistry was reduced to 66% and 64% respectively. Thus, we show for the first time that PSI, unlike PSII, becomes completely resistant to photoinhibition when plants are acclimated to either 20°C/800 μmol m⁻² s⁻¹ or 5°C/250 μmol m⁻² s⁻¹ as a response to growth at elevated excitation pressure. The role of temperature/light dependent acclimation in the induction of selective tolerance to PSI photoinactivation is discussed.

【 授权许可】

Unknown