背景回顾：Most extant angiosperms belong to Mesangiospermae, which comprises eudicots, monocots, magnoliids, Chloranthales and Ceratophyllales. 

提出问题：However, phylogenetic relationships between these five lineages remain unclear. 

主要研究：Here, we report the high-quality genome of a member of the Chloranthales lineage (Chloranthus sessilifolius). 

结果1-全基因组复制事件：We detect only one whole genome duplication within this species and find that polyploidization events in different Mesangiospermae lineage are mutually independent. 

结果2-花发育相关基因：We also find that the members of all floral development-related gene lineages are present in C. sessilifolius despite its extremely simplified flower. The AP1 and PI genes, however, show a weak floral tissue-specialized expression. 

结果3-系统发育关系：Our phylogenomic analyses suggest that Chloranthales and magnoliids are sister groups, and both are together sister to the clade comprising Ceratophyllales and eudicots, while the monocot lineage is sister to all other Mesangiospermae. 

结论：Our findings suggest that in addition to hybridization, incomplete lineage sorting may largely account for phylogenetic inconsistencies between the observed gene trees.

大多数现存的被子植物属于核心被子植物（Mesangiospermae），由真双子叶植物、单子叶植物、木兰类植物、金粟兰目以及金鱼藻目五大类群组成。但是，这五大被子植物支系之间的系统发育关系还不清楚。本文中，作者报道了一个来自金粟兰目的物种四川金粟兰的高质量参考基因组。作者检测到了一次特异于四川金粟兰的全基因组复制事件，发现不同核心被子植物支系中的多倍化事件都是相互独立的。作者还发现尽管四川金粟兰的花器官变得极度简化，但是所有与花发育相关的基因谱系均存在。但是，AP1和PI基因表现出比较弱的花组织特异性表达。作者通过系统发育基因组学分析发现，金粟兰目和木兰类植物是姊妹类群，共同作为金鱼藻目和真双子叶植物构成的类群的姊妹类群，而单子叶植物是其它所有核心被子植物构成的类群的姊妹类群。本文的研究结果表明除了杂交外，不完全谱系分选可能在很大程度上作用于所观察到的基因树之间的系统发育冲突。

背景回顾：Chloranthales remain the last major mesangiosperm lineage without a nuclear genome assembly. 

主要研究：We therefore assemble a high-quality chromosome-level genome of Chloranthus spicatus to resolve enigmatic evolutionary relationships, as well as explore patterns of genome evolution among the major lineages of mesangiosperms (eudicots, monocots, magnoliids, Chloranthales, and Ceratophyllales). 

结果1-共线性与WGD：We find that synteny is highly conserved between genomic regions of Amborella, Vitis, and Chloranthus. We identify an ancient single whole-genome duplication (WGD) (κ) prior to the divergence of extant Chloranthales. 

结果2-系统发育分析：Phylogenetic inference shows Chloranthales as sister to magnoliids. Furthermore, our analyses indicate that ancient hybridization may account for the incongruent phylogenetic placement of Chloranthales + magnoliids relative to monocots and eudicots in nuclear and chloroplast trees. 

结果3-基因特征：Long genes and long introns are found to be prevalent in both Chloranthales and magnoliids compared to other angiosperms. 

结论：Overall, our findings provide an improved context for understanding mesangiosperm relationships and evolution and contribute a valuable genomic resource for future investigations.

金粟兰目是核心被子植物中最后一个没有核基因组组装的谱系。本文中，作者组装了一个金粟兰高质量的染色体级别参考基因组，用以解析核心被子植物五大支系（真双子叶植物、单子叶植物、木兰类植物、金粟兰目以及金鱼藻目）那谜一般的系统演化关系及基因组演化模式。作者发现无油樟、葡萄及金粟兰的基因组存在高度保守的共线性关系。作者发现在现存金粟兰目分化之前发生过一次古老的单全基因组复制。系统发育分析显示金粟兰是木兰类植物的姊妹类群。此外，作者的分析显示古老的杂交可能是导致（金粟兰目 + 木兰类植物）与单、真双子叶之间在核和叶绿体基因组建树存在分歧的原因。相比于其它被子植物，金粟兰目和木兰类植物基因组上的基因和内含子普遍比较长。综上，本文的研究结果为理解核心被子植物的系统发育关系和演化提供了更好的背景，并为未来的研究提供了宝贵的基因组资源。