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Because of their great therapeutic and economic value, medicinal plants have attracted increasing scientific attention. With the rapid development of high-throughput sequencing technology, the genomes of many medicinal plants have been sequenced. Storing and analyzing the increasing volume of genomic data has become an urgent task. To solve this challenge, we have proposed the Traditional Chinese Medicine Plant Genome database (TCMPG, http://cbcb.cdutcm.edu.cn/TCMPG/), an integrative database for storing the scattered genomes of medicinal plants. TCMPG currently includes 160 medicinal plants, 195 corresponding genomes, and 255 herbal medicines. Detailed information on plant species, genomes, and herbal medicines is also integrated into TCMPG. Popular genomic analysis tools are embedded in TCMPG to facilitate the systematic analysis of medicinal plants. These include BLAST for identifying orthologs from different plants, SSR Finder for identifying simple sequence repeats, JBrowse for browsing genomes, Synteny Viewer for displaying syntenic blocks between two genomes, and HmmSearch for identifying protein domains. TCMPG will be continuously updated by integrating new data and tools for comparative and functional genomic analysis.

Background Agarwood, generated from the Aquilaria sinensis, has high economic and medicinal value. Although its genome has been sequenced, the ploidy of A. sinensis paleopolyploid remains unclear. Moreover, the expression changes of genes associated with agarwood formation were not analyzed either. Results In the present work, we reanalyzed the genome of A. sinensis and found that it experienced a recent tetraploidization event ~ 63–71 million years ago (Mya). The results also demonstrated that the A. sinensis genome had suffered extensive gene deletion or relocation after the tetraploidization event, and exhibited accelerated evolutionary rates. At the same time, an alignment of homologous genes related to different events of polyploidization and speciation were generated as well, which provides an important comparative genomics resource for Thymelaeaceae and related families. Interestingly, the expression changes of genes related to sesquiterpene synthesis in wounded stems of A. sinensis were also observed. Further analysis demonstrated that polyploidization promotes the functional differentiation of the key genes in the sesquiterpene synthesis pathway. Conclusions By reanalyzing its genome, we found that the tetraploidization event shaped the A. sinensis genome and contributed to the ability of sesquiterpenes synthesis. We hope that these results will facilitate our understanding of the evolution of A. sinensis and the function of genes involved in agarwood formation.

Polygala tenuifolia is a perennial medicinal plant that has been widely used in traditional Chinese medicine for treating mental disease. However, the lack of genomic resources limits the insight into its evolutionary and biological characterization. In the present work, we reported the P. tenuifolia genome, the first genome assembly of the Polygalaceae family. We sequenced and assembled this genome by a combination of Illumnina, PacBio HiFi, and Hi-C mapping. The assembly includes 19 pseudochromosomes covering ~92.68% of the assembled genome (~769.27 Mb). There are 36,463 protein-coding genes annotated in this genome. Detailed comparative genome analysis revealed that P. tenuifolia experienced two rounds of whole genome duplication that occurred ~39-44 and ~18-20 million years ago, respectively. Accordingly, we systematically reconstructed ancestral chromosomes of P. tenuifolia and inferred its chromosome evolution trajectories from the common ancestor of core eudicots to the present species. Based on the transcriptomics data, enzyme genes and transcription factors involved in the synthesis of triterpenoid saponin in P. tenuifolia were identified. Further analysis demonstrated that whole genome duplications and tandem duplications play critical roles in the expansion of P450 and UGT gene families, which contributed to the synthesis of triterpenoid saponins. The genome and transcriptome data will not only provide valuable resources for comparative and functional genomic researches on Polygalaceae, but also shed light on the synthesis of triterpenoid saponin.

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