Exploring the chemotypic variability of and by biochemical and genetic characterization.

The genus belonging to the Asteraceae family, is composed of two species, and , although, in the past, their classification was not always appropriate. While is very well known since ancient times for the medicinal properties of a blend of different flavonolignans contained in the achenes and named silymarin, very little information is available about chemodiversity. Here, we describe the biochemical characterization of a wide germplasm collection including 83 wild accessions collected during sampling campaigns in Italy, Spain, Iran and Algeria as well as accessions acquired by seed GenBanks and studied at both population and single plant level. Interestingly, our results confirm the presence of only three chemotypes in , namely A, B and C. Conversely, accessions, exhibit a distinct and stable chemotype (D) where isosilychristin is the predominant silymarin component. Additionally, DNA barcoding based on the ribosomal DNA region combined with morphological phenotyping and chemotyping, successfully resolves frequently found mistakes in the identification of the two species. These findings significantly expand our knowledge of the global biodiversity of the genus and provide valuable insights for future breeding programs and potential applications in nutrition and human health sciences.