Investigation of the HSF transcription factor, expression characteristics and stress tolerance function of PeHSF-2 in passion fruit (Passiflora edulis)

Research on passion fruit traits primarily focuses on abiotic stress due to its detrimental impact on the industry. Transcription factors (TFs) mitigate abiotic stress by participating in various biological processes, among which heat shock factors (HSFs) play a pivotal role in responding to both biotic and abiotic stresses and conferring stress tolerance. This study identified 15 PeHSF family members with complete sequences using a high-quality genome of passion fruit. A systematic analysis of PeHSFs across the genome was conducted through bioinformatics and transcriptome sequencing. Transcriptomic data revealed higher expression levels of most PeHSFs in fruit pulp at stages T1 and T2 compared with T3, demonstrating the family's responsiveness to diverse abiotic stresses. Subsequent subcellular localization confirmed nuclear localization of the selected gene PeHSF-2. Heterologous expression of PeHSF-2 in the INVSc1 yeast strain and Arabidopsis thaliana significantly enhanced tolerance to drought, salt, cold, and heat stresses. Furthermore, PeHSF-2 over-expression up-regulated stress-responsive genes (P5CS1, SOS1, HSP70, and CBF2), and interacted with PeSIP2-2. This study lays the groundwork for further investigation into the regulatory mechanisms of PeHSFs under abiotic stress conditions.