Journal Article

Photosynthetic Electron Flow Regulates Transcription of the <i>psaB </i>Gene in Pea (<i>Pisum sativum</i> L.) Chloroplasts Through the Redox State of the Plastoquinone Pool

Anna Tullberg, Krassimir Alexciev, Thomas Pfannschmidt and John F. Allen

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 41, issue 9, pages 1045-1054
Published in print September 2000 | ISSN: 0032-0781
Published online September 2000 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcd031
Photosynthetic Electron Flow Regulates Transcription of the psaB Gene in Pea (Pisum sativum L.) Chloroplasts Through the Redox State of the Plastoquinone Pool

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Plants respond to changing light conditions by altering the stoichiometry between components of the photosynthetic electron transport chain of chloroplast thylakoids. We measured specific run-on transcription of the chloroplast genes psaB, psbA and rbcL in pea (Pisum sativum L.) seedlings grown under three different conditions of illumination: light selective for photosystem I (PSI-light); light selective for photosystem II (PSII-light); and a combination of PSI- and PSII-light (mixed light, ML). The transcriptional rate of the psaB gene increased under PSII-light and decreased under PSI-light, while the transcriptional rates of the psbA and rbcL genes were affected only in a non-specific way. Similar effects also occurred in plants grown under ML and switched to either PSI- or PSII-light for 4 h. Addition of the inhibitors of photosynthetic electron transport 3-(3,4 dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) influenced psaB transcription in isolated, illuminated chloroplasts: DCMU addition resulted in oxidation of the plastoquinone pool and decreased transcription of psaB; DBMIB addition resulted in reduction of the plastoquinone pool and increased transcription of psaB. The experimental results obtained in vivo and in vitro provide evidence for coupling between the redox state of plastoquinone and the rate of transcription of the psaB gene in pea.

Keywords: Key words: Chloroplast — Photosynthesis — Pisum sativum L. — Plastoquinone — Redox — Transcription.; Abbreviations: CP47, chlorophyll-binding protein of 47 kDa relative moleular mass; DBMIB, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone; D1, reaction centre protein of PSII (psaB gene product); Fo, chlorophyll fluorescence emission when all PSII traps for excitation energy are open; Fm, chlorophyll fluorescence emission when all PSII traps for excitation energy are closed; Ft, chlorophyll fluorescence emission at time t; LHCII, light-harvesting pigment-protein complex of PS II; PSI-light, light absorbed by PSI more than by PSII; PSII-light, light absorbed by PSII more than by PSI; PQ, plastoquinone; ML, mixed light (PSI-light and PSII-light together); Rubisco, ribulose-1,5-bisphosphate carboxylase-oxygenase; QA, primary plastoquinone electron acceptor of PSII; WL, white light.

Journal Article.  7436 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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