Transcriptomics integrated with metabolomics reveals underlying mechanisms of cold-induced flesh bleeding in plum (cv. Friar) fruit during storage

An integrative analysis of the metabolomics and transcriptomics was conducted to reveal the underlying mechanisms responsible for the flesh bleeding of ‘Friar’ plum (Prunus salicina Lindl.) fruit subjected to cold storage. Results from quasi-targeted metabolomics showed that 115 differentially accumulated metabolites were detected and cyanidin derivatives were identified as the main components in red flesh. The accumulation of cyanidin-3-O-glucoside was further quantitatively proved using UPLC-MS. A weighted gene co-correlation network analysis was employed to obtain genes positively associated with flesh bleeding according to the comprehensive transcriptomic profiling, which was verified by Pearson’s correlation coefficient analysis. 21 differentially expressed genes were identified in the biosynthesis of anthocyanins, and 79 overlap up-regulated genes of transcription factors were identified as candidate regulators contributing to flesh bleeding in the fruit in response to cold stress. The up-regulation of genes involving in the MAPK cascade signal system participated in the ethylene signal transduction pathway under cold stress, which stimulates transcription factors and ultimately leads to the activation of structural genes associated with the biosynthesis of anthocyanins. The results of qRT-PCR verified the reliability of transcriptome data. These results would provide a new insight on the mechanism in flesh bleeding in plums during cold storage.