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

The APETALA2/ethylene response factor (AP2/ERF) family regulates plant responses to abiotic stresses, but the function of ERF transcription factors in kenaf drought tolerance remains unclear. In this study, HcERF5 was isolated from kenaf, and its role in drought stress tolerance was analyzed. Expression analysis revealed that HcERF5 is significantly induced by polyethylene glycol-6000 (PEG-6000) and abscisic acid (ABA) treatment in kenaf seedlings. Histochemical analysis of transgenic Arabidopsis plants containing the HcERF5 promoter-driven β-glucuronidase (GUS) reporter gene showed strong GUS activity in roots, stems, and leaves. Functional studies demonstrated that overexpression of HcERF5 in Arabidopsis enhanced seed germination rates under drought or ABA-induced stress and improved the drought tolerance of seedlings by elevating antioxidant enzyme activities. Conversely, aterf5 knockout lines exhibited response to drought stress. Additionally, HcERF5 -overexpressing plants exhibited reduced ABA sensitivity. Furthermore, virus-induced gene silencing (VIGS) of HcERF5 in kenaf resulted in a significant reduction in drought tolerance, as evident by decreased antioxidant enzyme activity, SPAD values, and increased stomatal aperture, malondialdehyde (MDA), reactive oxygen species (ROS), and proline levels under drought stress. RNA-seq analysis indicated that HcERF5 directly regulates the ABA signaling pathway. Yeast-two-hybrid (Y2H) assays identified 29 proteins interacting with HcERF5, and the downstream genes related to drought stress, including HcPRK , HcRD22 , HcMAP2 , HcCAB , HcCS , and HcCCoAOMT3 , showed significantly reduced in HcERF5 -silenced plants. These findings highlight the critical role of HcERF 5 in improving drought tolerance of kenaf through ABA-mediated signaling. • HcERF5 overexpression enhanced drought tolerance, however its silencing increased drought sensitivity in kenaf. • HcERF5 regulates of ABA biosynthesis and reduces stomatal conductance and density in kenaf under drought stress . • HcERF5 modulates plant hormone transduction, MAPK signaling, and phenylpropanoid biosynthesis under drought stress. • Protein interaction analysis revealed that HcERF5 interacts with six stress-responsive genes.