背景回顾：Artemisia argyi, as famous as Artemisia annua, is a medicinal plant with huge economic value in the genus of Artemisia and has been widely used in the world for about three thousand years. 

提出问题：However, a lack of the reference genome severely hinders the understanding of genetic basis for the active ingredient synthesis of A. argyi. 

主要发现：Here, we firstly report a complex chromosome-level genome assembly of A. argyi with a large size of 8.03 Gb, with features of high heterozygosity (2.36%), high repetitive sequences (73.59%) and a huge number of protein-coding genes (279,294 in total). 

结果1-基因组演化：WGD、TE、染色体融合：The assembly reveals at least three rounds of whole-genome duplication (WGD) events, including a recent WGD event in the A. argyi genome, and a recent burst of transposable element, which may contribute to its large genome size. The genomic data and karyotype analyses confirmed that A. argyi is an allotetraploid with 34 chromosomes. Intragenome synteny analysis revealed the chromosomes fusion event occurred in the A. argyi genome, which elucidates the changes of basic chromosome numbers in Artemisia genus. 

结果2-生物学特性：适应性广、次生代谢物含量高：Significant expansion of genes related to photosynthesis, DNA replication, stress responses and secondary metabolism were identified in A. argyi, explaining the extensive environmental adaptability and rapid growth characteristics. In addition, we analyzed genes involved in the biosynthesis pathways of flavonoids and terpenoids, and found that extensive gene amplification and tandem duplication contributed to the high contents of metabolites in A. argyi. 

结论：Overall, the reference genome assembly provides scientific support for evolutionary biology, functional genomics and breeding in A. argyi and other Artemisia species.

 摘 要 

艾蒿（Artemisia argyi），是一种与青蒿齐名的青蒿属药用植物，具有巨大的经济价值，在全球范围内已广泛应用约3000年。然而，由于缺乏参考基因组，严重阻碍了对艾蒿活性成分合成的遗传基础研究。本文中，作者首次报道了艾蒿的染色体水平基因组组装，大小为8.03 Gb，基因组杂合度高（2.36%）、重复序列占比大（占73.59%）、蛋白编码基因多（279,294个）。作者共检测到了至少三次全基因组复制（WGD）事件，包括最近在艾蒿基因组独立发生的一次WGD，以及最近的一次转座因子爆发，这可能是导致艾蒿基因组较大的原因。基因组数据和核型分析证实，艾蒿是一种具有34条染色体的异源四倍体。基因组内的共线性分析揭示了艾蒿基因组中发生的染色体融合事件，阐明了艾蒿属染色体数目的变化。作者进一步鉴定了艾蒿基因组中与光合作用、DNA复制、胁迫响应以及次生代谢相关基因的显著扩增，解释了艾蒿适应环境广泛和生长迅速的特点。此外，作者还分析了艾蒿基因组上参与类黄酮和萜类化合物生物合成通路的基因，发现广泛的基因扩增和串联重复作用于艾蒿中较高含量的次生代谢产物。综上，艾蒿的参考基因组为艾蒿及其他蒿属植物的演化生物学、功能基因组学以及育种提供了基础。

 黄璐琦