In vivo biochemical characterization of transcription factors regulating plant defense response to disease

Abstract

The timely, coordinated transcriptional control of large sets of genes in response to microbial pathogen challenge is crucial for plant resistance to disease. Accordingly, the study of transcription factors (TFs), sequence-specific DNA-binding proteins that mediate pathogen-regulated gene expression, is key to the understanding of plant defense responses. Research to date has implicated several members from different families of TFs in mediation of plant defense responses. Considerable activity has been focused on ethylene response factors, WRKY and Whirly factors, the TGA subfamily of basic-domain leucine-zipper (bZIP) proteins, and NPR1 protein (nonexpressor of pathogenesis-related genes 1), which regulates defense responses through its interaction with TGA factors. Whereas relatively few TFs had been shown to mediate pathogen-regulated gene expression a decade ago, recent genomics projects are identifying large numbers of new candidates. Elucidating the function of these TFs at the biochemical or molecular level will be a daunting task, but one which should be greatly facilitated by emerging technologies that permit the analysis of protein–DNA and protein–protein interactions in planta. Here we describe some of these technologies as they have been, or could be, applied to plant TFs implicated in regulating defense-related gene expression.

Keywords:

• gene expression
• chromatin immunoprecipitation
• protein–protein interactions
• tandem-affinity purification tagging
• resonance energy transfer
• protein-fragment complementation assay