PeDREB-1, an AP2/ERF Transcription Factor in Passiflora edulis Sims, Regulates Cold Stress Responses and Fruit Ripening

• Gene Family Expansion: The AP2/ERF superfamily was expanded to 94 members in passion fruit, including three novel genes, providing a comprehensive genomic resource. • Abiotic Stress Response: Numerous PeAP2/ERF genes, notably PeDREB-1, are dynamically and highly induced by abiotic stress, particularly cold. • PeDREB-1 in Cold Tolerance: Functional analysis in transgenic models demonstrates PeDREB-1 enhances cold tolerance by protecting photosynthesis and reducing oxidative membrane damage. • Repressor of Ripening: PeDREB-1 expression declines during maturation, and its VIGS-mediated silencing accelerates fruit ripening. • Breeding Potential: The dual function of PeDREB-1 makes it a promising target for engineering improved cold resilience and extended postharvest shelf life. Passion fruit is an important industrial crop with considerable economic value, yet its cultivation and postharvest quality are often limited by abiotic stresses. Expanding on previous work that identified 91 AP2/ERF transcription factors in passion fruit, this study reports three additional members— PeERF-54, PeERF-55 , and PeERF-56 —bringing the total to 94. We systematically investigated the roles of these PeAP2/ERF genes in abiotic stress adaptation and fruit maturation. Transcriptome profiling revealed that the majority of PeAP2/ERF s were differentially expressed under various abiotic stress conditions. During fruit pulp development, several members exhibited significantly higher expression at early (T1) and middle (T2) ripening stages compared to the late stage (T3). Notably, PeDREB-1 was strongly induced under cold stress. Meanwhile, transcriptomic data indicate that its expression levels decline progressively throughout fruit ripening, with expression levels at stage T1 being 1.82-fold and 5.49-fold higher than those at stages T2 and T3, respectively. Functional analyses in transgenic Saccharomyces cerevisiae and Arabidopsis thaliana demonstrated that PeDREB-1 enhances cold stress tolerance, supported by deeper staining and upregulation of stress-responsive genes. Moreover, transient overexpression and silencing assays in passion fruit revealed that PeDREB-1 delays ripening. Together, these results establish PeAP2/ERF transcription factors as key regulators of abiotic stress responses in passion fruit and identify PeDREB-1 as a dual-function regulator involved in both cold stress tolerance and the regulation of fruit ripening—an attribute of high relevance for industrial production and postharvest management.