Long-term drought stress induces structural and functional reorganization of photosystem II |
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Authors: | M T Giardi A Cona B Geiken T Kučera J Masojídek A K Mattoo |
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Institution: | (1) Italian National Council of Research (BEV-CNR), Area della Ricerca di Roma, Via Salaria km 29.3, I-00016 Monterotondo Scalo, Italy;(2) Plant Molecular Biology Laboratory, U.S. Department of Agriculture, BARC, 20705 Beltsville, MD, USA;(3) Present address: Department of Biology, Charles University, Prague, Czech Republic;(4) Present address: Institute of Microbiology, 37981 T ebo , Czech Republic |
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Abstract: | Long-term drought stress on photosystem II (PSII) was studied in pea (Pisum sativum L.) seedlings. Drought stress (reduction of water content by 35–80%) led to a considerable depletion of the PSII core, and the remaining PSII complex appeared to be functional and reorganized, with a unit size (LHCP/PSII core) twofold greater than that of well-irrigated plants. By immunoblotting analysis of the PSII proteins from grana and stroma lamellae, the enhanced degradation of CP43 and D1 proteins was observed in water-stressed plants. Also, water stress caused increased phosphorylation of the PSII core and increased D1 protein synthesis. Water-stress-mediated increase in D1 synthesis did not occur when plants were exposed to photoinhibitory light. The depletion of the PSII core was essentially reversed when water-stressed plants grown at low visible irradiance were watered. We suggest that the syndrome caused by the effect of long-term water stress on photosynthesis is a combination of at least two events: a reduction in the number of active PSII centres caused by a physical destabilization of the PSII core and a PSII reorganization with enhanced D1 turnover to counteract the core depletion.Abbreviations Chl
chlorophyll
- CP43 and CP47
-carotene-Chla-proteins of PSII core
- DCPIP
2,6-dichlorophenolindophenol
- DPC
diphenylcarbazide
- Fv/Fm
the ratio of yield of variable fluorescence to yield of maximal fluorescence when all reaction centres are closed
- LHC(P)
light-harvesting complex (proteins)
- Wc
water content
This work was supported by the Italian National Council of Research special grant RAISA, subproject 2 (paper No. 2179) on water stress B. Geiken was supported by the European program Human Capital and Mobility . We thank Dr. Roberto Barbato (Department of Biology, University of Padua, Italy) for generous gifts of various PSII antibodies. |
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Keywords: | D1 protein (turnover modification) Drought High irradiance Photosystem II (core phosphorylation) Pisum sativum (drought stress) Stress syndrome |
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