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Abscisic acid affects transcription of chloroplast genes via protein phosphatase 2C‐dependent activation of nuclear genes: repression by guanosine‐3′‐5′‐bisdiphosphate and activation by sigma factor 5
Author(s) -
Yamburenko Maria V.,
Zubo Yan O.,
Börner Thomas
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12876
Subject(s) - abscisic acid , biology , gene , transcription (linguistics) , promoter , psychological repression , rna polymerase , transcription factor , sigma factor , chloroplast , microbiology and biotechnology , gene expression , genetics , rna , linguistics , philosophy
Summary Abscisic acid ( ABA ) represses the transcriptional activity of chloroplast genes (determined by run‐on assays), with the exception of psbD and a few other genes in wild‐type Arabidopsis seedlings and mature rosette leaves. Abscisic acid does not influence chloroplast transcription in the mutant lines abi1‐1 and abi2‐1 with constitutive protein phosphatase 2C ( PP 2C) activity, suggesting that ABA affects chloroplast gene activity by binding to the pyrabactin resistance ( PYR )/ PYR 1‐like or regulatory component of ABA receptor protein family ( PYR / PYL / RCAR ) and signaling via PP 2Cs and sucrose non‐fermenting protein‐related kinases 2 (SnRK2s). Further we show by quantitative PCR that ABA enhances the transcript levels of RSH 2 , RSH 3 , PTF 1 and SIG 5 . RelA/SpoT homolog 2 ( RSH 2) and RSH 3 are known to synthesize guanosine‐3′‐5′‐bisdiphosphate (ppGpp), an inhibitor of the plastid‐gene‐encoded chloroplast RNA polymerase. We propose, therefore, that ABA leads to an inhibition of chloroplast gene expression via stimulation of ppGpp synthesis. On the other hand, sigma factor 5 ( SIG 5) and plastid transcription factor 1 ( PTF 1) are known to be necessary for the transcription of psbD from a specific light‐ and stress‐induced promoter (the blue light responsive promoter, BLRP ). We demonstrate that ABA activates the psbD gene by stimulation of transcription initiation at BLRP . Taken together, our data suggest that ABA affects the transcription of chloroplast genes by a PP 2C‐dependent activation of nuclear genes encoding proteins involved in chloroplast transcription.