Furanocoumarins in Heracleum species

The major amount of species of the Apiaceae family contain furanocoumarins. This type of chemicals can act as photosensitizing substances and be used in pharmacology. The giant hogweeds are the most well-known members of this family due to their photosensitizing properties. Their metabolic composition has been studied extensively, but the genomics of the genus Heracleum remains unexplored, as well as the metabolism of furanocoumarin synthesis in those plants. The reasons for the increased photosensitivity of giant hogweed compared to other species of Heracleum remain unknown. In this study, a comparison of the metabolic and genomic features of the aboveground organs of two Heracleum species was carried out: H. sosnowskyi, a giant hogweed with powerful photosensitizing activity, and H. sibiricum, which is non-invasive and “harmless”. It was shown that both species contain all known angular and linear compounds of the furanocoumarin synthesis pathway (from umbelliferone to isopimpinellin). The genomes of both species contain homologues of genes synthesizing both angular and linear furanocoumarins. However, the species differ significantly in the amount of those compounds. H. sibiricum synthesizes angular furanocoumarins much less actively, despite the genetic ability for such synthesis. H. sosnowskyi contains significantly more xanthotoxin than H. sibiricum. Interpopulation differences are observed both in the content of compounds and in the expression levels of biosynthetic genes. This is the first study to include a comparison of genomic and metabolomic data of closely related species of the Apiaceae in studying the biosynthesis of furanocoumarins.