[Identification of CBF genes in Panax quinquefolius and analysis of their expression under low temperature stress]

CBF/DREB1, a member of the DREB subfamily within the AP2/ERE transcription factor family, plays a pivotal role in plant cold tolerance and is highly conserved across higher plants. However, the research on the CBF gene family in Panax quinquefolius remains insufficient. In this study, seven PqCBF genes were identified in the P. quinquefolius genome, all classified into the CBF/DREB1 family and encoding unstable hydrophilic proteins. PqCBF proteins showcased highly conserved secondary and tertiary structures, each comprising one α-helix and two β-sheets. Subcellular localization predictions revealed nucleus-specific localization for PqCBF1, PqCBF2, PqCBF3, and PqCBF7, whereas PqCBF4, PqCBF5, and PqCBF6 exhibited nucleocytoplasmic dual localization. Chromosomal mapping showed that PqCBF genes were distributed across multiple chromosomes, with PqCBF2, PqCBF3, and PqCBF4 clustered on chromosome 14, indicative of potential genetic linkage. Promoter analysis identified multiple cis-acting elements associated with low-temperature, hormonal, and light-responsive signals, suggesting coordinated regulation through complex signaling networks. Both qRT-PCR and transcriptome analyses revealed cold stress-responsive expression patterns of PqCBF genes, demonstrating their functional involvement in cold stress adaptation. Furthermore, these genes showed distinct tissue-specific expression profiles in roots, stems, and leaves. This systematic characterization of the PqCBF gene family provides a theoretical foundation for elucidating the cold tolerance mechanisms in P. quinquefolius and advancing the development of cold-tolerant cultivars.