Genome-Wide Identification of the AP2/ERF Gene Family and Functional Analysis of PgAP2/ERF187 Under Cold Stress in Panax ginseng C. A. Meyer

<i>Panax ginseng</i> C. A. Meyer (<i>P. ginseng</i>) is a medicinal plant rich in bioactive components such as ginsenosides, polysaccharides, and volatile oils and is widely used in both the pharmaceutical and food industries. While the AP2/ERF gene family is well-documented to play crucial roles in plant growth, development, and defense responses, functional studies on this gene family in <i>P. ginseng</i> remain unreported. Our genome-wide analysis identified 318 PgAP2/ERF family members, which are classified into five subfamilies: AP2, DREB, ERF, RAV, and Soloist. Homology analysis revealed that segmental duplication serves as the primary evolutionary driver for the <i>PgAP2/ERF</i> gene family in <i>P. ginseng</i>. RT-qPCR analysis demonstrated that all <i>PgAP2/ERF</i> members in the DREB-A1 subgroup respond to cold stress. Specifically, we found that the DREB-A1 member <i>PgAP2/ERF187</i> plays a pivotal role in the cold stress response, with its expression specifically induced by ABA. Overexpression of <i>PgAP2/ERF187</i> in Arabidopsis significantly enhanced the expression of cold tolerance-related genes. Subcellular localization analysis confirmed the co-localization of PgABF and PgAP2/ERF187 in the nucleus. Combining transcription factor interaction predictions and yeast one-hybrid experiments, we propose that PgABF likely regulates <i>PgAP2/ERF187</i> expression by directly binding to its promoter region. These findings unveil the potential mechanism of the "PgABF-PgAP2/ERF187" regulatory module within the ABA signaling pathway during <i>P. ginseng</i>'s cold stress adaptation, thereby providing novel theoretical insights into the molecular mechanisms underlying <i>P. ginseng</i>'s cold resistance.