Integrated Metabolome and Transcriptome Analyses Reveal the Molecular Mechanism of a Color Mutation in Miniature Roses

Floral coloration is one of the most prominent traits in roses. In this study, to investigate the mechanism of color formation in miniature roses, metabolite biosynthesis and gene expression analyses were carried out on the Neptune King rose and its color mutant, Queen, at the blooming stage. A total of 190 flavonoid-related metabolites and 38,551 unique genes were identified. The contents of 45 flavonoid-related metabolites, and the expression of 15 of these metabolites related to flower pigmentation genes, were significantly different. Six anthocyanins were found to be the major metabolites, with a higher abundance in the Queen rose. The expression levels of 13 structural genes involved in the anthocyanin biosynthetic pathway showed an upregulation trend in the mutant flower, which may be the direct factor that resulted in the higher levels of anthocyanin in the mutant. To the best of our knowledge, this is the first study of rose flower coloration combining metabolome and transcriptome analyses. The results will help us to further understand the systematic regulation mechanisms of flower coloration in miniature roses. The obtained information will be conducive to modifying flower color through genetic transformation.