The persimmon genome reveals clues to the evolution of a lineage-specific sex determination system in plants
The persimmon genome reveals clues to the evolution of a lineage-specific sex determination system in plants
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DOI：
10.1371/journal.pgen.1008566
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发表时间：
2020-02-01
期刊：
影响因子：
4.5
通讯作者：
Henry, Isabelle M.
中科院分区：
文献类型：
--
作者：
Akagi, Takashi;Shirasawa, Kenta;Henry, Isabelle M.
大多数被子植物都有两性花，但也有少数物种进化出了异交策略，如雌雄异株，即存在单独的雄性和雌性个体。我们以前研究了二倍体柿（D。莲花），并发现雄花的抑制常染色体基因MeGI由它的parasiti，Y编码的假基因OGI。这种机制被认为是谱系特异性的，但其进化路径仍然未知。在这里，我们开发了一个完整的草案二倍体柿子基因组（D。lotus），这揭示了一个谱系特异性的全基因组复制事件，并提供了关于Y染色体结构的信息。我们还鉴定了三个旁系同源物，MeGI，OGI和新鉴定的Sister of MeGI（SiMeGI）。进化分析表明，在全基因组复制事件后，MeGI经历了适应性进化。用MeGI和SiMeGI转化烟草植物表明，MeGI特异性地获得了作为雄性器官发育抑制因子的新功能，而SiMeGI可能保持了原始功能。后来，一个片段性复制事件在Y染色体上产生了Megi的调节因子OGI，完成了导致二聚体的路径，并可能启动了Y染色体的形成。这些发现揭示了复制事件如何提供灵活的遗传物质，以帮助应对不同的环境，并为我们理解植物向雌雄异株过渡的机制提供了有趣的相似之处。作者摘要几十年来，植物的性行为一直吸引着科学家。大多数植物可以自我繁殖，但不是所有的。例如，一小部分物种已经进化出一种名为雌雄个体的系统。Dioclonal已经独立地进化了多次，虽然我们还不了解这些物种中许多Dioclonal的分子机制，但随着几种雌雄异株物种的最新进展，一幅画面开始出现。在这里，我们集中在进化事件导致柿diophyll。我们之前的工作已经确定了一对调节该物种性别的基因，称为OGI和MeGI。为了研究二倍体柿的进化历史，我们绘制了二倍体柿的全基因组序列。我们发现了一个谱系特异性的全基因组复制事件，并观察到MeGI在此事件后经历了适应性进化。转基因分析证实，MeGI新获得的男性抑制功能，而该基因的另一个副本，SiMeGI，没有。MeGI的监管机构OGI是第二次较小规模的分段复制事件的结果，最终完成了系统。这项研究揭示了复制作为促进灵活基因功能的机制的作用，以及它如何影响重要的生物功能，例如建立新的性系统。
Most angiosperms bear hermaphroditic flowers, but a few species have evolved outcrossing strategies, such as dioecy, the presence of separate male and female individuals. We previously investigated the mechanisms underlying dioecy in diploid persimmon (D. lotus) and found that male flowers are specified by repression of the autosomal gene MeGI by its paralog, the Y-encoded pseudo-gene OGI. This mechanism is thought to be lineage-specific, but its evolutionary path remains unknown. Here, we developed a full draft of the diploid persimmon genome (D. lotus), which revealed a lineage-specific whole-genome duplication event and provided information on the architecture of the Y chromosome. We also identified three paralogs, MeGI, OGI and newly identified Sister of MeGI (SiMeGI). Evolutionary analysis suggested that MeGI underwent adaptive evolution after the whole-genome duplication event. Transformation of tobacco plants with MeGI and SiMeGI revealed that MeGI specifically acquired a new function as a repressor of male organ development, while SiMeGI presumably maintained the original function. Later, a segmental duplication event spawned MeGI's regulator OGI on the Y-chromosome, completing the path leading to dioecy, and probably initiating the formation of the Y-chromosome. These findings exemplify how duplication events can provide flexible genetic material available to help respond to varying environments and provide interesting parallels for our understanding of the mechanisms underlying the transition into dieocy in plants.Author summary Plant sexuality has fascinated scientists for decades. Most plants can self-reproduce but not all. For example, a small subset of species have evolved a system called dioecy, with separate male and female individuals. Dioecy has evolved multiple times independently and, while we do not understand the molecular mechanisms underlying dioecy in many of these species yet, a picture is starting to emerge with recent progress in several dioecious species. Here, we focused on the evolutionary events leading to dioecy in persimmon. Our previous work had identified a pair of genes regulating sex in this species, called OGI and MeGI. We drafted the whole genome sequence of diploid persimmon to investigate their evolutionary history. We discovered a lineage-specific whole-genome duplication event, and observed that MeGI underwent adaptive evolution after this event. Transgenic analyses validated that MeGI newly acquired a male-suppressor function, while the other copy of this gene, SiMeGI, did not. The regulator of MeGI, OGI, resulted from a second smaller-scale segmental duplication event, finalizing the system. This study sheds light on the role of duplication as a mechanism that promote flexible genes functions, and how it can affect important biological functions, such as the establishment of a new sexual system.