Rott, Markus;
Martins, Nádia F.;
Thiele, Wolfram;
Lein, Wolfgang;
Bock, Ralph;
Kramer, David M.;
Schöttler, Mark A.
ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen
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Media type:
E-Article
Title:
ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen
Contributor:
Rott, Markus;
Martins, Nádia F.;
Thiele, Wolfram;
Lein, Wolfgang;
Bock, Ralph;
Kramer, David M.;
Schöttler, Mark A.
imprint:
American Society of Plant Biologists, 2011
Published in:The Plant Cell
Language:
English
ISSN:
1040-4651
Origination:
Footnote:
Description:
<p>Tobacco (Nicotiana tabacum) plants strictly adjust the contents of both ATP synthase and cytochrome b 6 f complex to the metabolic demand for ATP and NADPH. While the cytochrome b₆f complex catalyzes the rate-limiting step of photosynthetic electron flux and thereby controls assimilation, the functional significance of the ATP synthase adjustment is unknown. Here, we reduced ATP synthase accumulation by an antisense approach directed against the essential nuclearencoded γ-subunit (AtpC) and by the introduction of point mutations into the translation initiation codon of the plastidencoded atpB gene (encoding the essential ß-subunit) via chloroplast transformation. Both strategies yielded transformants with ATP synthase contents ranging from 100 to <10% of wild-type levels. While the accumulation of the components of the linear electron transport chain was largely unaltered, linear electron flux was strongly inhibited due to decreased rates of plastoquinol reoxidation at the cytochrome b₆f complex (photosynthetic control). Also, nonphotochemical quenching was triggered at very low light intensities, strongly reducing the quantum efficiency of CO₂ fixation. We show evidence that this is due to an increased steady state proton motive force, resulting in strong lumen overacidification, which in turn represses photosynthesis due to photosynthetic control and dissipation of excitation energy in the antenna bed.</p>