Abstract
We previously isolated the Arabidopsis sog1-1 (suppressor of gamma response) mutant as a second-site suppressor of the Ionizing Radiation (IR) sensitive phenotype of the repair defective xpf mutant. sog1-1 mutant appeared to be defective in a DNA damage-induced checkpoint, but the SOG1 gene was not identified. Here, we report that SOG1 encodes a putative transcription factor. This gene is a member of the NAC family (a family of proteins unique to land plants) and plays a central role in response to IR. Hundreds of genes are normally upregulated by IR in wild-type Arabidopsis. Surprisingly, almost every one of these genes is not induced in the sog1-1 mutant, suggesting that SOG1 is the master regulator of the transcriptional response to IR. These studies suggest that, in plants, signals related to genomic stress are processed through a single, central transcription factor- SOG1.
