Genome-Wide Identification of the AP2/ERF Transcription Factor Family and Expression Analysis Under Selenium Stress in Cardamine hupingshanensis

AP2/ERF (APETALA2/ethylene-responsive factor) is one of the largest plant transcription factor families, characterized by 1-2 AP2/ERF domains (≈60-70 amino acids) that regulate plant development and biotic/abiotic stress responses. This study presents the first genome-wide identification and characterization of the AP2/ERF family in the selenium (Se) hyperaccumulator <i>Cardamine hupingshanensis</i> via bioinformatics. A total of 230 <i>AP2/ERF</i> genes were identified, which were non-randomly distributed across 16 chromosomes. Their encoded proteins varied in length (126-623 aa), molecular mass (13.927-68.112 kDa), and isoelectric point (4.48-10.31). Phylogenetic analysis classified these genes into five conserved subfamilies (AP2, DREB, ERF, RAV, Soloist), consistent with other plant species. Intron distribution differed among subfamilies (42.17% of genes contained introns), and motif 1 was universally conserved. Promoter cis-element analysis revealed enrichment of hormone-, stress-, and growth-related elements, highlighting potential roles in abiotic stress responses (notably, light and abscisic acid signaling). Expression profiling under Se stress (100 μg Se/L and 80,000 μg Se/L) demonstrated tissue-specific, dose-dependent, and temporal dynamic patterns. This inaugural genome-wide investigation of <i>C. hupingshanensis</i> AP2/ERFs provides foundational datasets for deciphering regulatory networks governing growth and Se stress response in this Se hyperaccumulator plant.