Transcriptome analysis reveals the mechanism of peach fruit browning during cold storage

Peach fruit quality deteriorates rapidly at room temperature. Therefore, cold storage is commonly used to extend postharvest shelf life of peaches. However, prolonged cold storage can lead to chilling injury (CI), which manifests as internal browning and affects fruit quality. This study explored the physiological, biochemical and transcriptomic responses of two peach cultivars (CP9 and mini) during cold storage. CP9 exhibited significant internal browning, reduction in soluble solid content (SSC) and firmness, and rapid increase in ethylene production. In contrast, mini showed no browning, retained higher SSC, experienced a slower decline in firmness and increase in ethylene production. After storage, CP9 showed elevated malondialdehyde (MDA) levels and increased activities of polyphenol oxidase (PPO), peroxidase (POD), and laccase (LAC), which are associated with browning symptoms. Transcriptome analysis identified two key candidate genes, <i>PpPOD73</i> and <i>PpPOD1</i>, along with 10 transcription factors (<i>PpMYB62</i>, <i>PpNAC100</i>, <i>PpbHLH62/93/94</i> and <i>PpWRKY47/48/71/74/75</i>) related to enzymatic browning. Co-expression network and promoter analyses revealed regulatory connections between these transcription factors and browning-related genes. This study sheds light on molecular mechanisms underlying peach fruit browningduring cold storage.