Identification and Analysis of the <i>AP2/ERF</i> Gene Family in Barley Based on Pan-Genome and Pan-Transcriptome

<i>AP2/ERF</i> gene family is an important family of plant transcription factors, widely involved in various life activities. This study systematically identified the <i>AP2/ERF</i> gene family in 76 barley genomes based on the barley pan-genome, revealing a total of 22,681 family members. Through orthologous gene group analysis, these genes were categorized into 383 orthologous gene groups (OGGs), with core and noncore genes identified. The results indicate that the <i>AP2/ERF</i> gene family in barley cultivars and landraces exhibits greater genetic diversity compared to wild barley, while wild barley is enriched in noncore genes and subjected to stronger selective pressures. Furthermore, two significant <i>AP2/ERF</i> genes, <i>HvTEM1</i> and <i>HvCRF4</i>, were uncovered through selective pressure analysis, with pan-genome analysis suggesting their important roles in barley reproduction. This is the first pan-genomic analysis of the <i>AP2/ERF</i> gene family in barley, which reveals the evolutionary patterns and functional characteristics of the family in different barley categories. The findings provide new theoretical insights for the genetic improvement and precision breeding of barley.