Functional analysis of a TGA factor-binding site located in the promoter region controlling salicylic acid-induced NIMIN-1 expression in Arabidopsis

Genet Mol Res. 2010 Feb 2;9(1):167-75. doi: 10.4238/vol9-1gmr704.

Abstract

TGA factors play a key role in plant defense by binding to the promoter region of defense genes, inducing expression. Salicylic acid (SA) induces the expression of the gene encoding NIMIN-1, which interacts with NPR1/NIM1, a key regulator of systemic acquired resistance. We investigated whether the TGA2-binding motif TGACG located upstream of the NIMIN-1 gene is necessary for SA induction of NIMIN-1 expression. A mutated version of the NIMIN-1 promoter was created by site-directed mutagenesis. We generated T-DNA constructs in which native NIMIN-1 and mutated promoters were fused to green fluorescent protein and beta-glucuronidase reporters. We produced transgenic Arabidopsis plants and observed NIMIN-1 promoter-driven green fluorescent protein expression in the roots, petiole and leaves. Constructs were agroinfiltrated into the leaves for transient quantitative assays of gene expression. Using quantitative real-time RT-PCR, we characterized the normal gene response to SA and compared it to the response of the mutant version of the NIMIN-1 promoter. Both the native NIMIN-1 construct and an endogenous copy of NIMIN-1 were induced by SA. However, the mutated promoter construct was much less sensitive to SA than the native NIMIN-1 promoter, indicating that this TGA2-binding motif is directly involved in the modulation of SA-induced NIMIN-1 expression in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects*
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Basic-Leucine Zipper Transcription Factors / metabolism*
  • Binding Sites
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Gene Expression Regulation, Plant / drug effects*
  • Green Fluorescent Proteins / metabolism
  • Molecular Sequence Data
  • Mutation / genetics
  • Nuclear Proteins / metabolism*
  • Plants, Genetically Modified
  • Promoter Regions, Genetic*
  • Protein Binding / drug effects
  • Salicylic Acid / pharmacology*
  • Transcription Factors

Substances

  • AHBP-1b protein, Arabidopsis
  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • Carrier Proteins
  • NIMIN1 protein, Arabidopsis
  • Nuclear Proteins
  • Transcription Factors
  • Green Fluorescent Proteins
  • Salicylic Acid