Insights into the Superrosids Phylogeny and Flavonoid Synthesis from the Telomere-to-telomere Gap-free Genome Assembly of Pursh

The completion of the first telomere-to-telomere (T2T) genome assembly of Pursh (PC), a prominent medicinal plant in China, represents a significant achievement. This assembly spans a length of 257.5 Mb and consists of nine chromosomes. PC's notably smaller genome size in Saxifragales, compared to that of , can be attributed to the low abundance of transposable elements. By utilizing single-copy genes from 30 species, including 28 other Superrosids species, we successfully resolved a previously debated Superrosids phylogeny. Our findings unveiled Saxifragales as the sister group to the core rosids, with both being the sister group to Vitales. Utilizing previously characterized cytochrome P450 (CYP) genes, we predicted the compound classes that most CYP genes of PC are involved in synthesizing, providing insight into PC's potential metabolic diversity. Metabolomic and transcriptomic data revealed that the richest sources of the three most noteworthy medicinal components in PC are young leaves and flowers. We also observed higher activity of upstream genes in the flavonoid synthesis pathway in these plant parts. Additionally, through weighted gene co-expression network analysis, we identified gene regulatory networks associated with the three medicinal components. Overall, these findings deepen our understanding of PC, opening new avenues for further research and exploration.