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Plant Cell. 2015 Mar;27(3):839-56. doi: 10.1105/tpc.114.134809. Epub 2015 Mar 13.

Phosphorylation of trihelix transcriptional repressor ASR3 by MAP KINASE4 negatively regulates Arabidopsis immunity.

Author information

1
Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843 Provincial Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
2
Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843.
3
Department of Biochemistry and Biophysics, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843.
4
Department of Biology, Genetics Institute, Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32610.
5
Provincial Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
6
Department of Plant Pathology and Microbiology, Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843 lshan@tamu.edu.

Abstract

Proper control of immune-related gene expression is crucial for the host to launch an effective defense response. Perception of microbe-associated molecular patterns (MAMPs) induces rapid and profound transcriptional reprogramming via unclear mechanisms. Here, we show that ASR3 (ARABIDOPSIS SH4-RELATED3) functions as a transcriptional repressor and plays a negative role in regulating pattern-triggered immunity (PTI) in Arabidopsis thaliana. ASR3 belongs to a plant-specific trihelix transcription factor family for which functional studies are lacking. MAMP treatments induce rapid phosphorylation of ASR3 at threonine 189 via MPK4, a mitogen-activated protein kinase that negatively regulates PTI responses downstream of multiple MAMP receptors. ASR3 possesses transcriptional repressor activity via its ERF-associated amphiphilic repression motifs and negatively regulates a large subset of flg22-induced genes. Phosphorylation of ASR3 by MPK4 enhances its DNA binding activity to suppress gene expression. Importantly, the asr3 mutant shows enhanced disease resistance to virulent bacterial pathogen infection, whereas transgenic plants overexpressing the wild-type or phospho-mimetic form of ASR3 exhibit compromised PTI responses. Our studies reveal a function of the trihelix transcription factors in plant innate immunity and provide evidence that ASR3 functions as a transcriptional repressor regulated by MAMP-activated MPK4 to fine-tune plant immune gene expression.

PMID:
25770109
PMCID:
PMC4558661
DOI:
10.1105/tpc.114.134809
[Indexed for MEDLINE]
Free PMC Article

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