Screening and Expression Analysis of POD Gene in POD-H2O2 Pathway on Bud Dormancy of Pear (Pyrus pyrifolia)

Abstract

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 (H2O2) functions as a signalling molecule in the regulation of dormancy, with peroxidase (POD) playing a crucial role in governing H2O2 levels. Our prior transcriptomic and metabolomic investigations into diverse pear dormancy phases posited that POD predominantly oversees pear bud dormancy. In this study, we utilised qRT-PCR to screen the most significantly expressed gene, Pyrus pyrifolia POD4-like (PpPOD4-like), from seven POD genes. Subsequently, H2O2 test kits, overexpression methods, and subcellular localisation techniques were employed to assess changes in H2O2 content, POD activity, PpPOD4-like expression, and its cellular positioning during pear bud dormancy. Subcellular localisation experiments revealed that PpPOD4-like is situated on the cell membranes. Notably, H2O2 content exhibited a rapid increase during endodormancy and decreased swiftly after ecodormancy. The fluctuation pattern of POD activity aligned with that of H2O2 content. Additionally, PpPOD4-like expression was markedly upregulated, displaying an overall upward trajectory. Our findings indicate that PpPOD4-like modulates H2O2 levels by regulating POD activity, thereby actively participating in the intricate regulation of pear dormancy processes.