A chromosome-level genome of Astilbe chinensis unveils the evolution of a terpene biosynthetic gene cluster

Astilbe chinensis, a perennial ornamental plant in the Saxifragaceae family, is recognized for its medicinal properties due to its diverse secondary metabolites. Here, we generate a chromosome-level genome assembly of A. chinensis. Our analysis provides compelling evidence that A. chinensis experienced a whole-genome triplication event, which preceded the diversification of the Saxifragaceae family. Furthermore, we identify a biosynthetic gene cluster that includes nine terpene synthase (TPS) genes. Among these, the gene AcTPS2 encodes a eudesma-5,7-diene synthase, and the product is confirmed using nuclear magnetic resonance spectroscopy. A synteny analysis of this gene cluster across various representative plant species reveals variations in the number, sequence, and function of TPS genes, indicating that neo-functionalization of these TPS genes likely occurred after speciation. Collectively, the genome sequence of A. chinensis lays the foundation for genetic and evolutionary studies of the Saxifragaceae family and provides insights into terpene synthases discovery.