Transcription factor regulating the transcriptional activation response to gamma irradiation (PubMed:19549833). Required for stem-cell death induced by UVB or by gamma irradiation (PubMed:20634150). Not required for ATM activation, but participates in pathways governed by both ATM and ATR sensor kinases (PubMed:19549833). Involved in DNA damage response (DDR) system that regulates cell cycle arrest (PubMed:24399300). Functional homolog of animal p53 (PubMed:24736489). Regulates SMR5 and SMR7 transcription (PubMed:24399300). Regulates DNA repair and cytokinin signaling separately and plays a key role in controlling lateral root formation under genotoxic stress. Expressed in shoot and root apical meristems, in lateral root primordia, in the vasculature of young leaves and in the root stele. Not induced by zeocin or ionizing radiation treatment. The NAC domain includes a DNA-binding domain and a dimerization domain. Phosphorylated in a DNA stress-independent manner (PubMed:23907539, PubMed:24399300). Hyperphosphorylated on SQ motifs upon double-strand breaks, H(2)O(2) or zeocin treatments (PubMed:23907539, PubMed:24399300). Hyperphosphorylation is required for SOG1 function, and unlike constitutive phosphorylation, is ATM dependent (PubMed:23907539).