Stress- and pathogen-induced Arabidopsis WRKY48 is a transcriptional activator that represses plant basal defense

Mol Plant. 2008 May;1(3):459-70. doi: 10.1093/mp/ssn020. Epub 2008 May 8.

Abstract

Plant WRKY transcription factors can function as either positive or negative regulators of plant basal disease resistance. Arabidopsis WRKY48 is induced by mechanical and/or osmotic stress due to infiltration and pathogen infection and, therefore, may play a role in plant defense responses. WRKY48 is localized to the nucleus, recognizes the TTGACC W-box sequence with a high affinity in vitro and functions in plant cells as a strong transcriptional activator. To determine the biological functions directly, we have isolated loss-of-function T-DNA insertion mutants and generated gain-of-function transgenic overexpression plants for WRKY48 in Arabidopsis. Growth of a virulent strain of the bacterial pathogen Pseudomonas syringae was decreased in the wrky48 T-DNA insertion mutants. The enhanced resistance of the loss-of-function mutants was associated with increased induction of salicylic acid-regulated PR1 by the bacterial pathogen. By contrast, transgenic WRKY48-overexpressing plants support enhanced growth of P. syringae and the enhanced susceptibility was associated with reduced expression of defense-related PR genes. These results suggest that WRKY48 is a negative regulator of PR gene expression and basal resistance to the bacterial pathogen P. syringae.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • DNA Probes
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Regulation, Plant*
  • Kinetics
  • Molecular Sequence Data
  • Molecular Weight
  • Plant Diseases / microbiology*
  • Plant Diseases / prevention & control
  • Pseudomonas syringae / pathogenicity*
  • RNA, Plant / chemistry
  • RNA, Plant / genetics
  • RNA, Ribosomal / chemistry
  • RNA, Ribosomal / genetics
  • Salicylic Acid / pharmacology
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Arabidopsis Proteins
  • DNA Probes
  • DNA-Binding Proteins
  • RNA, Plant
  • RNA, Ribosomal
  • Trans-Activators
  • Transcription Factors
  • Salicylic Acid