The genome of Pseudotaxus chienii, a relict conifer endemic to China, provides insights into the origin and evolution of taxane biosynthesis

As a sister genus to Taxus, Pseudotaxus holds significant importance for studying the origin and evolution of the taxane biosynthesis pathway. However, the reference genome of P. chienii, the sole species of Pseudotaxus, is not yet available. We have completed a chromosome-level genome assembly of P. chienii, with a total length of 15.6 Gb. P. chienii possesses only a partial pathway for Taxol biosynthesis, which terminates before the enzyme taxane 2α-O-benzoyl transferase (TBT), a crucial enzyme responsible for the production of 10-deacetylbaccatin III. With the emergence of the Taxus genus, the limitation posed by TBT is overcome, allowing for the extension of the existing taxane biosynthesis pathway into a complete Taxol biosynthesis pathway. Protein structure analysis revealed that the structure of metal ion catalysis sites in taxadiene synthase (TS) is conserved across the Pseudotaxus and Taxus genera, providing potential sites for enhancing TS activity through enzyme engineering. This comparative genomic analysis contributes to our understanding of the origin and evolution of taxane biosynthesis within the Taxaceae family. In this study, we successfully assembled the Pseudotaxus genome and presented a reference-grade genome sequence of P. chienii, which contains 16.79 giga-bases (Gb) of data, 15.45 Gb of which was assigned to 12 pseudochromosomes. Our comparative genomic analysis contributes to our understanding of the origin and evolution of taxane biosynthesis and provides insights into the genome structure and organization of the Taxaceae family.