Abstract
In Arabidopsis genome, around 2,000 genes are believed to encode transcription factors. Although most of them have been considered as transcriptional activator, recent studies have revealed that a number of them appear to be transcriptional repressors since we identified the common sequence motif that acts as a repression domain. In this study we identified that more than 1,200 genes of 30,000 genes in Arabidopsis genome possessed the coding region of the repression motif and 250 of them encode transcription factors. This high frequency of repression motif in transcription factors is statistically significant suggesting that the motif should have a pivotal role in transcriptional gene regulation. We further examined whether the repression motif is conserved among genome-sequenced plants, namely rice, poplar, grape and Physcomitrella patens, and found that it was conserved in more than 160 transcription factors in two or more genome-sequence plants, suggesting that these transcription factors are transcriptional repressors.
