Abstract.
Light-chilling stress, the combination of low-light illumination and low temperature, preferentially inactivated photosystem I (PSI) of cucumber (Cucumis sativus L.) leaves, resulting in the photoinhibition of photosynthesis. The extent of PSI photoinhibition, determined in vivo by monitoring absorption changes around 810 nm (induced by far-red light), was closely correlated with the redox state of the PSII electron acceptor QA, measured as the chlorophyll fluorescence parameter, 1–qP, where qP is a photochemical quenching coefficient. In contrast, the decrease in the far-red-induced leaf absorptance signal was not well correlated with the limited fragmentation of the PsaA/B gene products in the PSI reaction center after the light-chilling stress. Amongst various enzymes involved in the photooxidative damage such as superoxide dismutase (SOD), ascorbate peroxidase, and NAD(P)H dehydrogenase, only SOD was inhibited by light-chilling treatment. Further, an approximately 3-fold increase in the leaf content of H2O2, a potent inhibitor of Cu/Zn-SOD, was observed after light-chilling stress. From these results, we suggest that Cu/Zn-SOD is the primary target of the light-chilling stress, followed by subsequent inactivation of PSI by reactive oxygen species.
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Choi, S., Jeong, S., Jeong, W. et al. Chloroplast Cu/Zn-superoxide dismutase is a highly sensitive site in cucumber leaves chilled in the light. Planta 216, 315–324 (2002). https://doi.org/10.1007/s00425-002-0852-z
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DOI: https://doi.org/10.1007/s00425-002-0852-z