Transcription factor involved in the symbiotic nodule signaling pathway in response to rhizobial stimulation. Functions as a transcriptional regulator required for root infection by symbiotic rhizobia, infection thread (IT) formation, and nodule development. May coordinate these processes (PubMed:28503742, PubMed:28028038, PubMed:28068194). Functions downstream of the CCAMK-CYCLOPS complex (PubMed:28503742, PubMed:28028038). Probably not involved in arbuscular mycorrhizal (AM) symbiosis (PubMed:28068194). Induced in nodules 7 days after rhizobial inoculation. No visible phenotype under normal growth conditions, but roots of mutant plants are impaired in the interaction with rhizobia, formation of infection threads (ITs) and nodule development. Belongs to the AP2/ERF transcription factor family. ERF subfamily.