The wild strawberry (Fragaria vesca L.; F. vesca) represents a resilient and extensively studied model organism. While the AP2/ERF gene family plays a pivotal role in plant development, its exploration within F. vesca remains limited. In this study, we characterized the AP2/ERF gene family in wild strawberries using the recently released genomic data (F. vesca V6.0). We conducted an analysis of the gene family expansion pattern, we examined gene expression in stem segments and leaves under cold conditions, and we explored its functional attributes. Our investigation revealed that the FvAP2/ERF family comprises 86 genes distributed among four subfamilies: AP2 (17), RAV (6), ERF (62), and Soloist (1). Tandem and segmental duplications significantly contributed to the growth of this gene family. Furthermore, predictive analysis identified several cis-acting elements in the promoter region associated with meristematic tissue expression, hormone regulation, and resistance modulation. Transcriptomic analysis under cold stress unveiled diverse responses among multiple FvAP2/ERFs in stem segments and leaves. Real-time fluorescence quantitative reverse transcription PCR (RT-qPCR) results confirmed elevated expression levels of select genes following the cold treatment. Additionally, overexpression of FvERF23 in Arabidopsis enhanced cold tolerance, resulting in significantly increased fresh weight and root length compared to the wild-type control. These findings lay the foundation for further exploration into the functional roles of FvAP2/ERF genes.

The AP2/ERF family of transcription factors is one of the most conserved and important transcription factor families, and it is ubiquitous in plants. It plays an essential role in plant morphogenesis, molecular mechanisms of stress responses, hormone signaling pathways, and synthesis of secondary metabolites. FaTINY2 was cloned from the octaploid strawberry Fragaria × ananassa for this investigation. Bioinformatics revealed that the protein possesses a conserved AP2 domain and is localized in the nucleus. When FaTINY2 was expressed in plants, quantitative analysis revealed that the gene was tissue-specific. There are lower contents of reactive oxygen species (ROS) and malondialdehyde (MDA), higher contents of proline, chlorophyll, and higher activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) in transgenic Arabidopsis thaliana than wild type (WT) and unload line (UL) plants under cold and salt stress. FaTINY2 plays a role in enhancing stress tolerance by regulating a few genes linked to the stress response. The findings of this study were that FaTINY2 transgenic Arabidopsis thaliana plants were more tolerant to salt and cold than WT and UL plants. In addition to offering a theoretical reference for strawberry production under stress, this research established a groundwork for exploration into the molecular mechanisms in which strawberries respond to cold and high salt stress.