Acts as a transcriptional activator of the phytosulfokine PSK5 peptide hormone. Binds to the GCC-box pathogenesis-related promoter element. Rate-limiting factor of quiescent center cell division active when surrounding stem cells are damaged. Is a proteolytic target of APC/C-FZR1 complex. Restricted to dividing quiescent center cells. Up-regulated by brassinosteroid, but not regulated by ethylene. Cleaved by the APC/C-FZR1 complex. Belongs to the AP2/ERF transcription factor family. ERF subfamily. Extended C-terminus.