Integrated Multiomics Analysis Sheds Light on the Mechanisms of Color and Fragrance Biosynthesis in Wintersweet Flowers

Wintersweet (<i>Chimonanthus praecox</i>) is known for its flowering in winter and its rich floral aroma; the whole flower is yellow and the inner petals are red. In this study, we chose the wintersweet genotypes HLT040 and HLT015 as the research materials, and studied the co-regulatory mechanism of color and fragrance of wintersweet through metabolomics and transcriptomics. This study found that there were more flavonoids in HLT015, and anthocyanins (cyanidin-3-O-rutinoside and cyanidin-3-O-glucoside) were only present in HLT015, but HLT040 contained more monoterpenes and FVBPs (phenylpropanoid volatile compounds) than HLT015. We constructed putative benzenoids and phenylpropanoid metabolism pathway as well as terpene metabolism pathways. We found some linkages between the different structural genes and metabolites for flower color and fragrance in wintersweet, and screened out 39 TFs that may be related to one or more structural genes in benzenoids and phenylpropanoid or terpene metabolism pathways. In the yeast one-hybrid assay, we found that CpERF7 was able to interact with the promoter of <i>CpANS1</i>, while CpbHLH50 and CpMYB21 interacted with the promoter of <i>CpTPS4</i>. This study provides a theoretical basis for understanding the co-regulatory mechanism of color and fragrance in wintersweet.