Integrated Transcriptome and Metabolome Analyses Provide Insights into the Coloring Mechanism of Dark-red and Yellow Fruits in Chinese Cherry [ Cerasus pseudocerasus (Lindl.) G. Don].

Chinese cherry [ Cerasus pseudocerasus (Lindl.) G. Don] is an important fruit tree from China that has excellent ornamental, economic, and nutritional values with various colors. The dark-red or red coloration of fruit, an attractive trait for consumers, is determined by anthocyanin pigmentation. In this study, the coloring patterns during fruit development in dark-red and yellow Chinese cherry fruits were firstly illustrated by integrated transcriptome and widely-targeted metabolome analyses. Anthocyanin accumulation in dark-red fruits was significantly higher compared with yellow fruits from the color conversion period, being positively correlated to the color ratio. Based on transcriptome analysis, eight structural genes ( CpCHS , CpCHI , CpF3H , CpF3'H , CpDFR , CpANS , CpUFGT , and CpGST ) were significantly upregulated in dark-red fruits from the color conversion period, especially CpANS , CpUFGT , and CpGST . On contrary, the expression level of CpLAR were considerably higher in yellow fruits than in dark-red fruits, especially at the early stage. Eight regulatory genes ( CpMYB4 , CpMYB10 , CpMYB20 , CpMYB306 , bHLH1 , CpNAC10 , CpERF106 , and CpbZIP4 ) were also identified as determinants of fruit color in Chinese cherry. Liquid chromatography-tandem mass spectrometry identified 33 and 3 differential expressed metabolites related to anthocyanins and procyanidins between mature dark-red and yellow fruits. Cyanidin-3- O -rutinoside was the predominant anthocyanin compound in both fruits, while it was 6.23-fold higher in dark-red than in yellow fruits. More accumulated flavanol and procyanidin contents resulted in less anthocyanin content in flavonoid pathway in yellow fruits due to the higher expression level of CpLAR . These findings can help understand the coloring mechanism of dark-red and yellow fruits in Chinese cherry, and provide genetic basis for breeding new cultivars.