Content area
Full text
A microarray based on PCR amplicons of 1,864 confirmed and predicted Arabidopsis transcription factor genes was produced and used to profile the global expression pattern in seedlings, specifically their light regulation. We detected expression of 1,371 and 1,241 genes in white-light- and dark-grown 6-d-old seedlings, respectively. Together they account for 84% of the transcription factor genes examined. This array was further used to study the kinetics of transcription factor gene expression change of dark-grown seedlings in response to blue light and the role of specific photoreceptors in this blue-light regulation. The expression of about 20% of those transcription factor genes are responsive to blue-light exposure, with 249 and 115 genes up or down-regulated, respectively. A large portion of blue-light-responsive transcription factor genes exhibited very rapid expression changes in response to blue light, earlier than the bulk of blue-light-regulated genes. This result suggests the involvement of transcription cascades in blue-light control of genome expression. Comparative analysis of the expression profiles of wild type and various photoreceptor mutants demonstrated that during early seedling development cryptochromes are the major photoreceptors for blue-light control of transcription factor gene expression, whereas phytochrome A and phototropins play rather limited roles.
The completed sequence of the Arabidopsis genome by the Arabidopsis Genome Initiative (2000) provides both an opportunity and a challenge to decipher the information hidden behind the vast number of nucleotides. An essential step toward understanding the meaning of the sequences from the Arabidopsis genome is to determine which ones are expressed and how their expression is regulated. The advancement of DNA microarray technology made it possible to monitor the transcription of a large number of genes in the genome in a high-throughput fashion. This approach has recently been used to define the transcriptional activities of all predicted genes in Arabidopsis chromosome 2 (Kim et al., 2003). It was reported that the expression of a significant fraction of known and predicted genes was confirmed. However, no comprehensive studies have yet been reported that analyze the genome expression profile for an entire functional group of genes in Arabidopsis.
Transcription factor genes constitute one of the most important functional groups of Arabidopsis genes. Because transcription factors perform regulatory roles in the expression of their target genes, the overall expression profiles of...