Abscisic acid represses the transcription of chloroplast genes

• Published in: Journal of experimental botany Vol. 64; no. 14; pp. 4491 - 4502
• Main Authors: Yamburenko, Maria V, Zubo, Yan O, Vanková, Radomíra, Kusnetsov, Victor V, Kulaeva, Olga N, Börner, Thomas
• Format: Journal Article
• Language: English
• Published: England Oxford University Press [etc.] 01.11.2013; Oxford University Press
• Subjects: abscisic acid; Abscisic Acid - pharmacology; barley; benzyladenine; chlorophyll; chloroplasts; Chloroplasts - drug effects; Chloroplasts - genetics; Chloroplasts - radiation effects; cytokinins; Cytokinins - pharmacology; gene expression; Gene Expression Regulation, Plant - drug effects; Gene Expression Regulation, Plant - radiation effects; genes; Genes, Chloroplast - genetics; Hordeum - drug effects; Hordeum - genetics; Hordeum - radiation effects; Hordeum vulgare; leaves; Light; messenger RNA; photosynthesis; Plant Growth Regulators - pharmacology; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - growth & development; proteins; RESEARCH PAPER; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; Time Factors; Transcription, Genetic - drug effects; Transcription, Genetic - radiation effects; senescence; cytokinin; regulation of transcription; chloroplast; Abscisic acid (ABA); photosynthesis; retrograde signalling; nucleus-encoded plastid RNA polymerase (NEP); Hordeum vulgare (L.); plastid-encoded plastid RNA polymerase (PEP)
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ert258

Numerous studies have shown effects of abscisic acid (ABA) on nuclear genes encoding chloroplast-localized proteins. ABA effects on the transcription of chloroplast genes, however, have not been investigated yet thoroughly. This work, therefore, studied the effects of ABA (75 μM) on transcription and steady-state levels of transcripts in chloroplasts of basal and apical segments of primary leaves of barley (Hordeum vulgare L.). Basal segments consist of young cells with developing chloroplasts, while apical segments contain the oldest cells with mature chloroplasts. Exogenous ABA reduced the chlorophyll content and caused changes of the endogenous concentrations not only of ABA but also of cytokinins to different extents in the basal and apical segments. It repressed transcription by the chloroplast phage-type and bacteria-type RNA polymerases and lowered transcript levels of most investigated chloroplast genes drastically. ABA did not repress the transcription of psbD and a few other genes and even increased psbD mRNA levels under certain conditions. The ABA effects on chloroplast transcription were more pronounced in basal vs. apical leaf segments and enhanced by light. Simultaneous application of cytokinin (22 μM 6-benzyladenine) minimized the ABA effects on chloroplast gene expression. These data demonstrate that ABA affects the expression of chloroplast genes differentially and points to a role of ABA in the regulation and coordination of the activities of nuclear and chloroplast genes coding for proteins with functions in photosynthesis.