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Cell Host Microbe. 2018 Apr 11;23(4):485-497.e5. doi: 10.1016/j.chom.2018.03.010.

The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the Nucleus and Regulates Defense Hormone Expression during Plant Innate Immunity.

Author information

1
Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA. Electronic address: nkrlal@ucdavis.edu.
2
Department of Plant Biology, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA.
3
Departments of Chemistry, and Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
4
Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA.
5
Department of Plant Pathology, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616, USA.
6
Department of Biochemistry and Biophysics and Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
7
Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011, USA.
8
Department of Plant Pathology and Microbiology and Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
9
Departments of Chemistry, and Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA. Electronic address: ajfisher@ucdavis.edu.
10
Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA. Electronic address: spdineshkumar@ucdavis.edu.

Abstract

Plants employ cell-surface pattern recognition receptors (PRRs) to detect pathogens. Although phytohormones produced during PRR signaling play an essential role in innate immunity, a direct link between PRR activation and hormone regulation is unknown. EFR is a PRR that recognizes bacterial EF-Tu and activates immune signaling. Here we report that EFR regulates the phytohormone jasmonic acid (JA) through direct phosphorylation of a receptor-like cytoplasmic kinase, BIK1. The BIK1 structure revealed that the EFR-phosphorylated sites reside on a uniquely extended loop away from the BIK1 kinase core domain. Phosphomimetic mutations of these sites resulted in increased phytohormones and enhanced resistance to bacterial infections. In addition to its documented plasma membrane localization, BIK1 also localizes to the nucleus and interacts directly with WRKY transcription factors involved in the JA and salicylic acid (SA) regulation. These findings demonstrate the mechanistic basis of signal transduction from PRR to phytohormones, mediated through a PRR-BIK1-WRKY axis.

KEYWORDS:

BIK1; EFR; PRR; RLCK; WRKY; innate immunity; jasmonic acid (JA); receptor-like cytoplasmic kinase; salicylic acid (SA)

PMID:
29649442
PMCID:
PMC6266874
DOI:
10.1016/j.chom.2018.03.010
[Indexed for MEDLINE]
Free PMC Article

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