The sesquiterpenoids and their chemotaxonomic implications in Senecio L. (Asteraceae)

• Seven sections were divided among 149 species according to 618 sesquiterpenoids.
• Two ways of sesquiterpenoids evolution were found in the seven chemical sections.
• The eremophilanes skeleton was the primitive sesquiterpenoid type in Senecio.
• Taxonomic value of sesquiterpenoids was well supported by molecular data in Senecio.

Sesquiterpenoids are important characteristic compounds in Asteraceae plants. These compounds have been proposed to be potential chemotaxonomic markers, but this application has not been comprehensively investigated. In this paper, sesquiterpenoids from 149 species of the genus Senecio were investigated to assess their taxonomic utility. The presence and absence were encoded as binary taxonomic characteristics and subsequently utilised in a clustering analysis. The previously biosynthesis pathway of sesquiterpenoids was taken into account to explore the relationship among these species contained different sesquiterpenoid types. In addition, the DNA phylogeny was also considered to explore the distribution and evolution of sesquiterpenoids in genus Senecio further. As a result, seven chemical major sections within the Senecio were recognised based on the chemical character. Although with several exceptions, the biosynthesis pathway, molecular phylogeny and the geographical origin of these sesquiterpenoid were found to be related to the chemical sections, which largely confirmed the validity of our chemo-classification for genus Senecio. In conclusion, we suggest that the sesquiterpenoid character in Senecio has some value for the genus taxonomy but should be analysed carefully and critically.