Ethylene Response Factor EjERF23 From Loquat Promotes Cold Tolerance via Directly Regulating <i>EjPOD</i> Gene Participated in Scavenging of Hydrogen Peroxide

In higher plants, ethylene response factors (ERFs) play crucial roles in orchestrating cold stress signal transduction. This study validated EjERF23 in loquat (Eriobotrya japonica Lindl.) and elucidated its role in cold tolerance. The transcriptional expression of EjERF23 was augmented upon exposure to the ethylene precursor 1-aminocyclopropane-1-carboxylate and low temperatures. Concurrently, it was inhibited by the ethylene inhibitor aminoethoxyvinylglycine under cold conditions. Overexpression of EjERF23 in transgenic tobacco enhanced cold tolerance, exhibiting significantly increased peroxidase (POD) activity, leading to reduced hydrogen peroxide (H₂O₂) accumulation and improved antioxidant stress tolerance. Further analysis revealed that EjERF23 directly interacts with the EjPOD47 promoter, increasing its transcriptional level. The outcomes of the yeast expression assay indicated that EjPOD47 has notable functions in the response to cold stress. Tobacco lines that were genetically modified and treated with POD inhibitors exhibited elevated content of H₂O₂ and a remarkable decrease in cold tolerance. The findings indicated that the EjERF23 protein is crucial for enhancing cold tolerance by positively regulating genes that code for POD to eliminate reactive oxygen species. Our findings offer fresh perspectives on the molecular regulatory mechanisms that govern the ethylene signaling pathway related to responses to cold stress.