The Arabidopsis immune adaptor SRFR1 interacts with TCP transcription factors that redundantly contribute to effector-triggered immunity

Plant J. 2014 Jun;78(6):978-89. doi: 10.1111/tpj.12527. Epub 2014 May 23.


The plant immune system must be tightly controlled both positively and negatively to maintain normal plant growth and health. We previously identified SUPPRESSOR OF rps4-RLD1 (SRFR1) as a negative regulator specifically of effector-triggered immunity. SRFR1 is localized in both a cytoplasmic microsomal compartment and in the nucleus. Its TPR domain has sequence similarity to TPR domains of transcriptional repressors in other organisms, suggesting that SRFR1 may negatively regulate effector-triggered immunity via transcriptional control. We show here that excluding SRFR1 from the nucleus prevented complementation of the srfr1 phenotype. To identify transcription factors that interact with SRFR1, we screened an Arabidopsis transcription factor prey library by yeast two-hybrid assay and isolated six class I members of the TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factor family. Specific interactions were verified in planta. Although single or double T-DNA mutant tcp8, tcp14 or tcp15 lines were not more susceptible to bacteria expressing AvrRps4, the triple tcp8 tcp14 tcp15 mutant displayed decreased effector-triggered immunity mediated by the resistance genes RPS2, RPS4, RPS6 and RPM1. In addition, expression of PATHOGENESIS-RELATED PROTEIN2 was attenuated in srfr1-4 tcp8-1 tcp14-5 tcp15-3 plants compared to srfr1-4 plants. To date, TCP transcription factors have been implicated mostly in developmental processes. Our data indicate that one function of a subset of TCP proteins is to regulate defense gene expression in antagonism to SRFR1, and suggest a mechanism for an intimate connection between plant development and immunity.

Keywords: Arabidopsis thaliana; Pseudomonas syringae; SRFR1; TCP transcription factors; effector-triggered immunity; transcriptional regulation; yeast two-hybrid assay.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / immunology*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / analysis
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Binding Sites
  • Cell Nucleus / metabolism
  • Disease Resistance / genetics
  • Gene Expression Regulation, Plant
  • Mutation
  • Plant Diseases / immunology
  • Plant Immunity / genetics*
  • Protein Transport
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription Factors / physiology
  • Two-Hybrid System Techniques


  • Arabidopsis Proteins
  • SRFR1 protein, Arabidopsis
  • Transcription Factors