Transcriptomic analyses of Chrysanthemum morifolium Ramat under UV-B radiation treatment reveal variations in the metabolisms associated with bioactive components

Ultraviolet-B is an effective elicitor that enhances the production of bioactive ingredient in various plants. However, the mechanism underlying ultraviolet-B responses in the genus Chrysanthemum is largely unknown. Chrysanthemum morifolium Ramat is used as herbal medicine, beverage material, and seasoning in many Asian regions. A massive amount of bioactive ingredients, such as caffeoylquinic acids and flavonoids, are contained in C. morifolium flowers and leaves, leading to an extensive number of applications for their extracts. In this study, complementary DNA libraries from Chrysanthemum morifolium Ramat leaves under ultraviolet-B radiation at various time points (0 h, 3 h, 6 h and 12 h) were separately sequenced. A large number of differential expressed genes were screened during the ultraviolet-B radiation process. The expression of most glycosylsis-, glycosyltransferase-related genes, flavonoid, fatty acid and caffeoylquinic acid biosynthesis related genes were largely induced by ultraviolet-B radiation. Furthermore, the contents of flavonoids, caffeoylquinic acids and fatty acids were significantly induced by ultraviolet-B radiation, suggesting a close relationship between the contents of flavonoids, caffeoylquinic acids and fatty acids and the resistance of plant to ultraviolet-B-induced stress. Our data provides a comprehensive resource for identifying genes associated with ultraviolet-B-induced variations in the bioactive ingredients of C. morifolium.