Transcriptional activator involved in the hypoxic stress response (PubMed:20113439, PubMed:21615413, PubMed:21398256, PubMed:24728113, PubMed:32977426). Acts as a transcriptional activator via the cis-acting element GCC box (PubMed:24728113, PubMed:32977426). Plays a role in low oxygen signaling and contributes to tolerance to anoxia stress by enhancing anaerobic gene expression and ethanolic fermentation (PubMed:20113439, PubMed:21398256). Invovlved in the modulation of ethylene responses under both normoxia and hypoxia (PubMed:21398256). Is mostly responsible for transactivation of hypoxia-responsive genes. Involved in root development through the regulation of root meristem cell division (PubMed:24728113). Does not act as a transcriptional activator via the cis-acting CRT/DRE element (PubMed:24728113). Expressed in roots and at lower levels in shoots. Highly expressed in roots and leaf trichomes (PubMed:24728113). Expressed in rosette leaves, stems, cauline leaves and flowers (PubMed:24728113). Induced under hypoxic conditions in roots (PubMed:20113439, PubMed:21615413, PubMed:21398256, PubMed:24395201, PubMed:24728113, PubMed:32977426). Induced during hypoxia under nitrate nutrition (PubMed:30535180). Induced by ethylene (PubMed:21398256, PubMed:28698356). Induced by hydrogen peroxide (PubMed:24395201). In presence of oxygen, the N-terminal cysteine residue (Cys-2) of ERF73 can be oxidized by cysteine oxidases, thus preparing the protein for N-end rule pathway-mediated proteasomal degradation (Probable). Under low oxygen levels, Cys oxidation is prevented, ERF73 is stabilized and confers tolerance to hypoxia (Probable). Seedlings silencing ERF73 exhibit reduced elongation of the primary root (PubMed:21398256). Seedlings overexpressing ERF73 exhibit increased elongation of the primary root (PubMed:32977426). Plants overexpressing ERF73 exhibit increased tolerance to hypoxia treatment (PubMed:32977426). Plants overexpressing ERF73 exhibit increase tolerance to submergence. Belongs to the AP2/ERF transcription factor family. ERF subfamily.