Integrative transcriptome and metabolome analysis reveals candidate genes related to terpene synthesis in Chrysanthemum × morifolium

BACKGROUND: Chrysanthemum (Chrysanthemum × morifolium) is one of the four major cut flowers worldwide and is valued for ornamental, culinary, and medicinal purposes. Terpenoids are key components of the fragrance of chrysanthemum; they not only serve to repel insect herbivores and promote pollination but also impact the value of the plant. However, the terpene production of chrysanthemum and the regulatory mechanisms involved remain unclear. RESULTS: We used gas chromatography‒mass spectrometry (GC‒MS) to identify 177 compounds, including 106 terpenes, in ten chrysanthemum cultivars. Monoterpene derivatives and sesquiterpenes were the most common. Next, we identified 27 candidate hub genes for terpene production in chrysanthemum via combined transcriptome and metabolome analysis, as well as weighted gene coexpression network analysis. The three terpenes synthesis-related genes were significantly expressed in the disc florets of the different chrysanthemum cultivars. We concluded that the transcription factors TCP8, TCP5, ATHB8, ATHB7, HAT22, TGA1, TGA4, and WHY1 may regulate terpene synthesis. CONCLUSIONS: In this study, we profiled terpenes in chrysanthemum florets and constructed a key terpene-transcription factor network related to terpene synthesis. These findings lay the groundwork for future research into the mechanism of terpene synthesis in chrysanthemum as well as in other plants.