The AP2/ERF transcription factor HcERF5 confers drought tolerance via ABA-mediated signaling in kenaf

The APETALA2/ethylene response factor (AP2/ERFs) are pivotal in regulating abiotic stress responses in plants. However, the specific role of ERFs in kenaf’s response to drought stress remains unclear. In this study, a transcription factors HcERF5 was isolated from kenaf and its role in drought stress tolerance was analyzed. HcERF5 was found to localize in both nucleus and cytoplasm and could be significantly induced by polyethylene glycol-6000 (PEG-6000) and abscisic acid (ABA) in kenaf seedlings. In transgenic Arabidopsis expressing the HcERF5 promoter-driven β-glucuronidase (GUS), strong GUS activity was observed in roots, stems, and leaves. Overexpression of HcERF5 in Arabidopsis enhanced seed germination rates under drought or ABA stress and improved drought tolerance in seedlings by increasing antioxidant enzyme activities, whereas aterf5 knockout lines exhibited the opposite trend. Additionally, HcERF5 overexpressing Arabidopsis showed significantly increased drought tolerance and reduced sensitivity to ABA. Furthermore, virus-induced gene silencing (VIGS) of HcERF5 in kenaf reduced drought tolerance, as evidenced by decreased antioxidant enzyme activity, increased stomatal aperture, and elevated levels of malondialdehyde (MDA), reactive oxygen species (ROS), and proline under drought stress. RNA-seq analysis further revealed that HcERF5 directly regulated ABA signaling pathway. Yeast-two-hybrid (Y2H) assays revealed 29 proteins that interact with HcERF5. Among them, the expression of downstream drought stress-related genes HcPRK , HcRD22 , HcMAP2 , HcCAB , HcCS , and HcCCoAOMT3 were significantly reduced in HcERF5 -silenced plants. Overall, this study highlights the significant potential of HcERF 5 in enhancing drought tolerance in kenaf.