24-Epibrassinolide improves chilling tolerance by regulating PpCBF5-mediated membrane lipid metabolism in peach fruit.

• 24-Epibrassinolide (EBR) treatment alleviates chilling injury of peach fruit. • EBR treatment enhances chilling tolerance by regulating membrane lipid metabolism. • EBR treatment upregulates the gene expression of PpCBF5. • PpCBF5 negatively regulates the transcriptions of PpPLD and PpLipase. 24-Epibrassinolide plays an important role in regulating abiotic stress, which may enhance cold resistance of fruits and vegetables. C-repeat binding factor (CBF) has a rapid response to cold stress and is a crucial transcription factor for cold signal pathway. This study investigated the potential effect of EBR treatment on membrane lipid metabolism and the possible regulation mechanism of PpCBF5 to membrane lipid metabolism in peach fruit. The results showed that EBR treatment effectively suppressed the increase in activities and gene expression of phospholipase D, lipoxygenase and lipase, inhibited the hydrolysis of phosphatidylcholine and phosphatidylinositol to pohosphatidic acid, reduced the malondialdehyde content, and enhanced unsaturated fatty acids contents, thus alleviated the membrane lipid peroxidation and maintained the stability of cell membrane. In addition, the results of molecular assays in vivo, including dual luciferase reporter assay, in vivo bioluminescence imaging, yeast one hybrid and transient overexpression assay, showed that PpCBF5 negatively regulated the transcription of PpPLD and PpLipase. In conclusion, EBR treatment enhanced chilling tolerance of peach fruit through regulating membrane lipid metabolism and PpCBF5 might act as a crucial regulatory factor on membrane lipid metabolism. [ABSTRACT FROM AUTHOR]