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Dominant Repression by Arabidopsis Transcription Factor MYB44 Causes Oxidative Damage and Hypersensitivity to Abiotic Stress
Department of Applied Genetics and Cell Biology (DAGZ), University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 18, Vienna A-1190, Austria
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 11 December 2013; in revised form: 17 January 2014 / Accepted: 28 January 2014 / Published: 13 February 2014
Abstract: In any living species, stress adaptation is closely linked with major changes of the gene expression profile. As a substrate protein of the rapidly stress-induced mitogen-activated protein kinase MPK3, Arabidopsis transcription factor MYB44 likely acts at the front line of stress-induced re-programming. We recently characterized MYB44 as phosphorylation-dependent positive regulator of salt stress signaling. Molecular events downstream of MYB44 are largely unknown. Although MYB44 binds to the MBSII element in vitro, it has no discernible effect on MBSII-driven reporter gene expression in plant co-transfection assays. This may suggest limited abundance of a synergistic co-regulator. MYB44 carries a putative transcriptional repression (Ethylene responsive element binding factor-associated Amphiphilic Repression, EAR) motif. We employed a dominant repressor strategy to gain insights into MYB44-conferred stress resistance. Overexpression of a MYB44-REP fusion markedly compromised salt and drought stress tolerance—the opposite was seen in MYB44 overexpression lines. MYB44-mediated resistance likely results from induction of tolerance-enhancing, rather than from repression of tolerance-diminishing factors. Salt stress-induced accumulation of destructive reactive oxygen species is efficiently prevented in transgenic MYB44, but accelerated in MYB44-REP lines. Furthermore, heterologous overexpression of MYB44-REP caused tissue collapse in Nicotiana. A mechanistic model of MAPK-MYB-mediated enhancement in the antioxidative capacity and stress tolerance is proposed. Genetic engineering of MYB44 variants with higher trans-activating capacity may be a means to further raise stress resistance in crops.
Keywords: abiotic stress; mitogen-activated protein kinase (MAPK); reactive oxygen species; MYB; repression motif; Arabidopsis
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MDPI and ACS Style
Persak, H.; Pitzschke, A. Dominant Repression by Arabidopsis Transcription Factor MYB44 Causes Oxidative Damage and Hypersensitivity to Abiotic Stress. Int. J. Mol. Sci. 2014, 15, 2517-2537.
Persak H, Pitzschke A. Dominant Repression by Arabidopsis Transcription Factor MYB44 Causes Oxidative Damage and Hypersensitivity to Abiotic Stress. International Journal of Molecular Sciences. 2014; 15(2):2517-2537.
Persak, Helene; Pitzschke, Andrea. 2014. "Dominant Repression by Arabidopsis Transcription Factor MYB44 Causes Oxidative Damage and Hypersensitivity to Abiotic Stress." Int. J. Mol. Sci. 15, no. 2: 2517-2537.