Integrated transcriptomic and metabolomic analyses reveal the characteristics of volatile oils in Chrysanthemum morifolium

Chrysanthemum morifolium is a plant widely applied to ornamental, tea and medicinal uses with volatile oils as one of its main active ingredients. However, there are few studies on the differences in volatile oils between different flowering stages and different parts of the inflorescence. In this study, ‘Zaoxiaoyangju’ (ZXYJ), a C. morifolium variety of different floral stages and parts were used as research materials to analyze the transcriptome and the metabolome levels. A total of 63 metabolites were detected by GCMS– in the volatile oil samples, 44 of which were terpenoids. In addition, Dehydrosesquicineole, a sesquiterpenoid similar in structure to alpha-bisabolol and not previously reported in C. morifolium, was detected. A total of 45 differentially expressed terpenoid synthase genes (TPSs) were found and used to analyze the changes in the transcriptomic profiles of terpenoids in different samples. Both terpenoids and their related genes were differentially expressed in the four groups of samples. The results of this study can provide a basis for the difference of ZXYJ flavor in different floral stages and parts, and lay a foundation for the functional characterization of TPSs in ZXYJ.