Implications of alternative electron sinks in increased resistance of PSII and PSI photochemistry to high light stress in cold-acclimated Arabidopsis thaliana
| Autor: | Leonid V. Savitch, Alexander G. Ivanov, M. Rosembert, Paulina Stachula, Dominic Rosso, N. P. A. Huner, Vaughan Hurry, Gunnar Öquist |
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| Rok vydání: | 2012 |
| Předmět: |
Time Factors
Photosystem II Light Acclimatization Immunoblotting Arabidopsis Electrons Plant Science Biology Xanthophylls Photochemistry Photosystem I Glyceraldehyde Biochemistry Plastid terminal oxidase Fluorescence Electron Transport Stress Physiological Cold acclimation Photons P700 Photosystem I Protein Complex food and beverages Photosystem II Protein Complex Cell Biology General Medicine Chlororespiration Carbon Dioxide Photochemical Processes Electron transport chain Cold Temperature Plant Leaves Photorespiration Oxidation-Reduction Densitometry |
| Zdroj: | Photosynthesis research. 113(1-3) |
| ISSN: | 1573-5079 |
| Popis: | Exposure of control (non-hardened) Arabidopsis leaves to high light stress at 5 °C resulted in a decrease of both photosystem II (PSII) (45 %) and Photosystem I (PSI) (35 %) photochemical efficiencies compared to non-treated plants. In contrast, cold-acclimated (CA) leaves exhibited only 35 and 22 % decrease of PSII and PSI photochemistry, respectively, under the same conditions. This was accompanied by an accelerated rate of P700(+) re-reduction, indicating an up-regulation of PSI-dependent cyclic electron transport (CET). Interestingly, the expression of the NDH-H gene and the relative abundance of the Ndh-H polypeptide, representing the NDH-complex, decreased as a result of exposure to low temperatures. This indicates that the NDH-dependent CET pathway cannot be involved and the overall stimulation of CET in CA plants is due to up-regulation of the ferredoxin-plastoquinone reductase, antimycin A-sensitive CET pathway. The lower abundance of NDH complex also implies lower activity of the chlororespiratory pathway in CA plants, although the expression level and overall abundance of the other well-characterized component involved in chlororespiration, the plastid terminal oxidase (PTOX), was up-regulated at low temperatures. This suggests increased PTOX-mediated alternative electron flow to oxygen in plants exposed to low temperatures. Indeed, the estimated proportion of O(2)-dependent linear electron transport not utilized in carbon assimilation and not directed to photorespiration was twofold higher in CA Arabidopsis. The possible involvement of alternative electron transport pathways in inducing greater resistance of both PSII and PSI to high light stress in CA plants is discussed. |
| Databáze: | OpenAIRE |
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