The Cycas genome and the early evolution of seed plants

第一作者：Yang Liu

第一单位：深圳华大基因

通讯作者：Shouzhou Zhang

 Abstarct 

背景回顾：Cycads represent one of the most ancient lineages of living seed plants. Identifying genomic features uniquely shared by cycads and other extant seed plants, but not non-seed-producing plants, may shed light on the origin of key innovations, as well as the early diversification of seed plants. 

苏铁是现存所有种子植物中最古老的支系之一。鉴别苏铁与其他现存种子植物独特的基因组特征，可能有助于揭示关键创新的起源，以及种子植物的早期多样化。

主要研究：Here, we report the 10.5-Gb reference genome of Cycas panzhihuaensis, complemented by the transcriptomes of 339 cycad species. 

本文中，作者报告了攀枝花苏铁10.5Gb的参考基因组，以及339种苏铁的转录组。

结果1-系统发育+WGD：Nuclear and plastid phylogenomic analyses strongly suggest that cycads and Ginkgo form a clade sister to all other living gymnosperms, in contrast to mitochondrial data, which place cycads alone in this position. We found evidence for an ancient whole-genome duplication in the common ancestor of extant gymnosperms. 

核和质体系统发育基因组学分析显示，苏铁和银杏一起与其他所有现存裸子植物为姊妹枝，而线粒体数据仅支持苏铁与其他所有裸子植物为姊妹枝。作者在现存裸子植物的共同祖先中鉴定到了一次古老的全基因组复制。

结果2-基因水平转移：The Cycas genome contains four homologues of the fitD gene family that were likely acquired via horizontal gene transfer from fungi, and these genes confer herbivore resistance in cycads. 

苏铁基因组中包含4个fitDgene家族的同源基因，这些同源基因可能是通过来自真菌的水平基因转移获得，从而赋予了苏铁对草食性动物的抗性。

结果3-性别分化：The male-specific region of the Y chromosome of C. panzhihuaensis contains a MADS-box transcription factor expressed exclusively in male cones that is similar to a system reported in Ginkgo, suggesting that a sex determination mechanism controlled by MADS-box genes may have originated in the common ancestor of cycads and Ginkgo.

攀枝花苏铁Y染色体的雄性特异性区域包含了一个在雄性球果中广泛表达的MADS-box转录因子，这与银杏中报道的系统类似，表明由MADS-box基因控制的性别决定机制可能起源于苏铁和银杏的共同祖先。

结论：The C. panzhihuaensis genome provides an important new resource of broad utility for biologists.

攀枝花苏铁基因组为生物学家提供了一个具有广泛用途的重要新资源。

** 张寿洲 **

doi: https://doi.org/10.1038/s41477-022-01129-7

​Journal: Nature Plants

Published date: April 18, 2022