Effects of severe CO2 starvation on the photosynthetic electron transport chain in tobacco plants |
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Authors: | Durchan Milan Vácha František Krieger-Liszkay Anja |
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Institution: | Department of Photosynthesis, Institute of Plant Molecular Biology, Branisovská 31, CZ-37005, Ceské Budejovice, Czech Republic, durchan@umbr.cas.cz. |
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Abstract: | Tobacco plants (Nicotiana tabacum) were kept in CO2 free air for several days to investigate the effect of lack of electron acceptors on the photosynthetic electron transport
chain. CO2 starvation resulted in a dramatic decrease in photosynthetic activity. Measurements of the electron transport activity in
thylakoid membranes showed that a loss of Photosystem II activity was mainly responsible for the observed decrease in photosynthetic
activity. In the absence of CO2 the plastoquinone pool and the acceptor side of Photosystem I were highly reduced in the dark as shown by far-red light effects
on chlorophyll fluorescence and P700 absorption measurements. Reduction of the oxygen content of the CO2 free air retarded photoinhibitory loss of photosynthetic activity and pigment degradation. Electron flow to oxygen seemed
not to be able to counteract the stress induced by severe CO2 starvation. The data are discussed in terms of a donation of reducing equivalents from mitochondria to chloroplasts and a
reduction of the plastoquinone pool via the NAD(P)H-plastoquinone oxidoreductase during CO2 starvation.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | CO2 starvation water stress photosynthetic electron flow chlororespiration |
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