ERD15 promotes peach and tomato ripening by activating polyamine catabolism

Polyamine oxidase (PAO) is a key enzyme in polyamine (PA) catabolism and plays a vital role during fruit ripening. However, regulatory mechanisms that control PAO expression during maturation remain unclear. This study identifies the transcription factor PpeERD15 through yeast one-hybrid (Y1H) screening with the PpePAO1 promoter. ERD15 (early response to dehydration 15), a member of the early response to dehydration protein family, is known for its role in abiotic stress responses, but its function in fruit ripening remains largely unexplored. Subcellular localization analysis demonstrated that PpeERD15 was localized in both the nucleus and cytoplasm. Y1H and LUC assays confirmed that PpeERD15 directly binds the PpePAO1 promoter. Transient silencing of PpEDR15 in peach fruit downregulated PpePAO1 expression, promoted PA accumulation, inhibited ethylene production, increased fruit firmness, and delayed fruit ripening. Conversely, overexpression of PpeEDR15 upregulated PpePAO1, decreased PA content, promoted ethylene production, reduced fruit firmness, and accelerated fruit ripening. The role of homologous gene of ERD15 was also validated in tomato. This study discovered that PpeEDR15 regulates fruit ripening by promoting PA catabolism via PpePAO1 expression.