The Aquilegia genome reveals a hybrid origin of core eudicots

First author: Gökçe Aköz; Affiliations: Gregor Mendel Institute (孟德尔研究所): Vienna, Austria

Corresponding author: Magnus Nordborg 

Whole-genome duplications (WGDs) have dominated the evolutionary history of plants. One consequence of WGD is a dramatic restructuring of the genome as it undergoes diploidization, a process under which deletions and rearrangements of various sizes scramble the genetic material, leading to a repacking of the genome and eventual return to diploidy. Here, we investigate the history of WGD in the columbine genus Aquilegia, a basal eudicot, and use it to illuminate the origins of the core eudicots. Within-genome synteny confirms that columbines are ancient tetraploids, and comparison with the grape genome reveals that this tetraploidy appears to be shared with the core eudicots. Thus, the ancient gamma hexaploidy found in all core eudicots must have involved a two-step process: first, tetraploidy in the ancestry of all eudicots, then hexaploidy in the ancestry of core eudicots. Furthermore, the precise pattern of synteny sharing suggests that the latter involved allopolyploidization and that core eudicots thus have a hybrid origin. Novel analyses of synteny sharing together with the well-preserved structure of the columbine genome reveal that the gamma hexaploidy at the root of core eudicots is likely a result of hybridization between a tetraploid and a diploid species.

全基因组复制事件主宰了植物的演化历史。全基因组复制事件其中一个后果便是基因组在经历二倍体化时发生了剧烈的重组，在此过程中，各种各样的缺失和重排拼凑整个遗传物质，最终导致基因组重新组合形成二倍体。本文中，作者研究了一个基础双子叶植物毛茛科耧斗菜属的全基因组复制历史，并探讨了核心双子叶植物的起源。基因组内共线性分析确认了耧斗菜是一个古老的四倍体，与葡萄基因组的共线性分析显示该四倍化事件是与所有核心双子叶植物共享的。因此，在所有核心双子叶植物中所发现的古六倍化，即gamma事件包含了两个过程：首先，所有双子叶植物的祖先发生了一次古四倍化事件；而后所有核心双子叶植物的祖先发生了古六倍化事件。此外，精确的共线性共享模式说明后面的那次全基因组加倍事件是异源多倍体化事件，因此核心双子叶植物是杂合起源的。新的共线性分析以及结构相对保存完好的耧斗菜基因组揭示了核心双子叶祖先的gamma六倍化事件很有可能是一次四倍体和二倍体物种杂交的结果。

通讯：Magnus Nordborg (https://www.oeaw.ac.at/gmi/research/research-groups/magnus-nordborg/)

个人简介：1989年，瑞典隆德大学；学士；1994年，美国斯坦福大学，博士；1994-1997年，美国芝加哥大学，博士后。

研究方向：演化基因组学。

doi: https://doi.org/10.1186/s13059-019-1888-8

Journal: Genome Biology

Published date: November 28, 2019