The Arabidopsis Book ©2002 American Society of Plant Biologists Transcriptional Regulation: a Genomic Overview José Luis Riechmann Mendel Biotechnology, 21375 Cabot Blvd., Hayward, CA 94545, USA e-mail:
[email protected] and California Institute of Technology, Division of Biology 156-29, Pasadena, CA 91125 e-mail:
[email protected] Abstract The availability of the Arabidopsis thaliana genome sequence allows a comprehensive analysis of transcriptional regulation in plants using novel genomic approaches and methodologies. Such a genomic view of transcription first necessitates the compilation of lists of elements. Transcription factors are the most numerous of the different types of proteins involved in transcription in eukaryotes, and the Arabidopsis genome codes for more than 1,500 of them, or approximately 6% of its total number of genes. A genome-wide comparison of transcription factors across the three eukaryotic kingdoms reveals the evolutionary generation of diversity in the components of the regulatory machinery of transcription. However, as illustrated by Arabidopsis, transcription in plants follows similar basic prin- ciples and logic to those in animals and fungi. A global view and understanding of transcription at a cellular and organismal level requires the characterization of the Arabidopsis transcriptome and promoterome, as well as of the interactome, the localizome, and the phenome of the proteins involved in transcription. Introduction. Many of the biological processes in a plant are regulated mutations in transcription factors (Peng et al., 1999), at the level of transcription. Changes in gene expression alterations in their expression (Doebley et al., 1997; Wang have been shown to underlie the response to et al., 1999b), or changes in the expression of other types environmental cues and stresses (such as light, of regulatory proteins (Frary et al., 2000).