Abscisic acid (ABA) action on plastid transcription in Arabidopsis
Zusammenfassung der Projektergebnisse
We have analyzed the effects of ABA on chloroplast gene expression in Hordeum vulgare and wild-type and mutant lines of Arabidopsis thaliana. Exogenous ABA has mainly repressive effects on the transcriptional activity of chloroplast genes in codyledons and leaves. Also transcript levels are affected. The action on ABA on chloroplast gene expression is influenced by the light conditions and the age/developmental state of the leaves. ABA controls chloroplast gene expression via the well investigated signal transduction route from PYR/PYL/RCAR to PP2C, SNKR2 and transcription factors like ABI4. ABA induces changes in the transcriptional activity of nuclear genes coding for chloroplast-localized proteins. It represses the activity of photosynthesis genes and activates genes coding for sigma factor 5 (SIG5), transcription factor PTF1 and of enzymes for the synthesis of ppGpp (RSH2, RSH3) within the chloroplast. It is known that ppGpp binds to the plastid-gene encoded RNA polymerase PEP. Binding of ppGpp inhibits the activity of PEP explaining the observed repression of most genes by ABA. In this way, ABA down-regulates in a coordinated manner nuclear and chloroplast genes encoding components of the photosynthetic dark- and light reactions as part of the plant’s stress response. On the other hand, SIG5 and PTF1 direct PEP to chloroplast promoters of a few genes coding for proteins of the reaction center of photosystem II (psbA, psbD-psbC, probably also psbB) resulting in an ongoing active transcription of these genes supposedly important for the photoprotection of PSII.
Projektbezogene Publikationen (Auswahl)
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(2011) Methyl jasmonate, gibberellic acid and auxin affect transcription and transcript accumulation of chloroplast genes in barley. J. Plant Physiol. 168: 1334-1344
Zubo YO, Yamburenko M V, Kusnetsov VV, Börner T
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(2013) ABA represses the transcription of chloroplast genes. J. Exp. Bot. 64, 4491-4502
Yamburenko MV, Zubo YO, Vanková R, Kusnetsov VV, Kulaeva ON, Börner, T
