image: TwTPS5 knockout disrupts DASA biosynthesis and increases valuable terpenoids
Credit: ©Science China Press
Plants in the genus Tripterygium, historically utilized in traditional medicine and agriculture across East Asia, have been applied for pest control as well as for curing diseases such as rheumatoid arthritis and ankylosing spondylitis. T. wilfordii, commonly known as Thunder God Vine (雷公藤, named after a powerful deity in Chinese mythology to signify its potent therapeutic and toxic properties), has attracted worldwide interest due to its remarkable effects in the treatment of inflammations, obesity, and cancers. However, its clinical application is constrained by its toxicity, with frequent reports of severe adverse effects and even fatal poisoning. Considerable efforts have been made to alleviate the poisonousness of T. wilfordii by pre-treatments, including herbal processing, herbal compatibility, and dosage control, however their effects remain non-specific and limited.
Tripterygium plants are exceptionally rich in natural products of different classes, with more than 500 compounds identified, including dihydroagarofuran sesquiterpene alkaloids (DASAs), diterpenoids, triterpenoids, and others. Diterpenoids like triptolide are the major active constituents against immune system disorders and male fertility, while triterpenoids like celastrol are predominantly anti-obesity, and DASAs, such as wilforgine, exhibit potent insecticidal activities. Among the three classes, diterpenoids and triterpenoids are considered the major medicinal principals, whereas DASAs are mainly valuable as pesticides and piscicides. As the most efficient and crucial therapeutics for the treatment of rheumatoid arthritis, the potential multi-organ toxicity prevents the wide use of T. wilfordii in clinical practice. Advances in precise gene-editing technologies have opened avenues for the genetic improvement of T. wilfordii.
In this study, researchers integrated genomic, transcriptomic, and metabolomic data sets from Celastraceae species to elucidate the biosynthesis of DASAs. In vitro enzyme assays have led to the identification of gamma-selinene synthase conserved in this family. Importantly, knockout of TwTPS5 by CRISPR/Cas9 blocked the biosynthesis of DASAs, while the bioactive diterpenoids and triterpenoids were elevated, resulting in an innovative medicinal plant germplasm with reduced toxicity and enhanced pharmaceutical potential.
The first authors of this study are PhD candidates Liu Xinyue and Li Yufei from the Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences (CAS). Professor Fang Xin from the Kunming Institute of Botany, CAS, and Professor Chen Xiaoya from the Center for Excellence in Molecular Plant Sciences served as co-corresponding authors. This work was supported by the National Key R&D Program of China (2020YFA0907901), the Yunnan Revitalization Talent Support Program "Top Team" Project (202305AT350001), and the National Natural Science Foundation of China (32388201).
Journal
Science China Life Sciences