Postharvest 24-epibrassinolide treatment improves chilling resistance of peach fruit via PpHDT1 modulating brassinosteroid metabolism

Brassinosteroids (BRs) exhibit a positive effect on facilitating chilling resistance in fruits and vegetables. However, the change and regulatory mechanism of BR metabolism in fruits and vegetables are poorly understood. This study aimed to explore the underlying relationship among chilling injury (CI), BR metabolism and regulatory factor PpHDT1. The results showed that exogenous 24-epibrassinolide (EBR) retarded peaches CI, reduced endogenous brassinolide (BL) accumulation, repressed the transcriptions of BR synthesis-related genes, promoted expression of BR signal-related genes. The results of molecular assays in vivo demonstrated that PpHDT1 down-regulated BR synthesis gene PpDWF4 and up-regulated BR signal transduction gene PpBZR1. Moreover, EBR treatment enhanced PpHDT1 expression, revealing that EBR treatment might alleviate peaches CI through PpHDT1 modulating BL metabolism and signal pathway. Our study provides a new insight into the underlying mechanism of EBR on regulating chilling resistance in postharvest peaches.