Metabolome and Transcriptome Analysis Reveals Mechanisms Underlying Different Anthocyanin Biosynthesis Affecting Floral Color of Impatiens balsamina

Impatiens balsamina is a widely distributed ornamental plant known for its attractive floral colors and significant pharmaceutical value. Anthocyanins are responsible for the floral coloration of I. balsamina. However, the regulatory mechanisms of anthocyanin biosynthesis in the various colors of I. balsamina flowers remain unclear. In this study, we combined metabolome and transcriptome analysis of five groups of I. balsamina with white, pink, red, purple, and magenta flowers. The metabolome analysis identified anthocyanidins, including cyanidin, pelargonidin, delphinidin, peonidin, petunidin, and malvidin, in the petals of I. balsamina. Lower total anthocyanin levels were detected in white and pink flowers compared to red, purple, and magenta flowers. The red coloration was attributed to high concentrations of pelargonidin glucosides, while purple coloration was due to malvidin glucosides. Magenta flowers contained a high percentage of both malvidin and pelargonidin glucosides. Differentially expressed structural genes such as IbCHS1, IbF3H, IbF3′H, IbF3′5′H1, IbF3′5′H2, IbDFR1, IbOMT1, IbOMT2 and IbOMT3 were identified through transcriptome analysis. Furthermore, co-expression analysis identified candidate transcription factors correlated with these structural genes. This study provides new insights into the regulatory mechanisms of anthocyanin biosynthesis in I. balsamina, and offers a theoretical basis for the directed breeding of varieties with new floral colors.