| Summary: | Bud endodormancy represents a pivotal and intricate biological process influenced by both genetic and epigenetic factors, the exact mechanism of which remains elusive. Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) functions as a signalling molecule in the regulation of dormancy, with peroxidase (POD) playing a crucial role in governing H<sub>2</sub>O<sub>2</sub> levels. Our prior transcriptomic and metabolomic investigations into diverse pear dormancy phases posited that <i>POD</i> predominantly oversees pear bud dormancy. In this study, we utilised qRT-PCR to screen the most significantly expressed gene, Pyrus pyrifolia <i>POD4-like</i> (<i>PpPOD4-like</i>), from seven <i>POD</i> genes. Subsequently, H<sub>2</sub>O<sub>2</sub> test kits, overexpression methods, and subcellular localisation techniques were employed to assess changes in H<sub>2</sub>O<sub>2</sub> content, POD activity, <i>PpPOD4-like</i> expression, and its cellular positioning during pear bud dormancy. Subcellular localisation experiments revealed that PpPOD4-like is situated on the cell membranes. Notably, H<sub>2</sub>O<sub>2</sub> content exhibited a rapid increase during endodormancy and decreased swiftly after ecodormancy. The fluctuation pattern of POD activity aligned with that of H<sub>2</sub>O<sub>2</sub> content. Additionally, <i>PpPOD4-like</i> expression was markedly upregulated, displaying an overall upward trajectory. Our findings indicate that <i>PpPOD4-like</i> modulates H<sub>2</sub>O<sub>2</sub> levels by regulating POD activity, thereby actively participating in the intricate regulation of pear dormancy processes.
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