Chromosome-scale genome assembly of Artabotrys hexapetalus provides insights into its evolution and terpenoid biosynthesis.

Artabotrys hexapetalus is used as traditional Chinese medicine for the treatment of malaria. Its antimalarial activity has been shown to be the result of the sesquiterpene designated as yingzhaosu A (YZSA), which mainly occurs in the roots of A. hexapetalus. Despite its medicinal significance, the genetic basis and molecular mechanisms underlying the biosynthesis of its active terpenoids remain unclear. In this study, a high-quality chromosome-scale genome of A. hexapetalus was first reported. In total, 915.15 Mb of genome sequences were assembled, of which 911.58 Mb was sorted into 8 chromosomes. Phylogenetic analysis indicated that the divergence between the genera Artabotrys and Annona happened at approximately 45.77 million years ago (Mya) and the Annonaceae family diverged from other Magnolia species about 103.58 Mya. An ancient whole genome duplication (WGD) event was discovered in the A. hexapetalus genome, earlier than the divergence between Annonaceae and Magnoliaceae families. It correlates with a significant expansion of gene families related to secondary metabolism, especially the terpene synthase (TPS) and cytochrome P450 (P450) families. The analysis of TPS, P450, and 2-oxoglutarate/Fe(II)-dependent dioxygenase (2-ODD) gene families provides a foundation for future functional studies. Additionally, three putative terpene biosynthetic gene clusters were identified within the genome. Our work provides a foundation for elucidating the complete biosynthetic pathway of terpenoids in A. hexapetalus in the future.