Epigenetic reprogramming rewires transcription during the alternation of generations in Arabidopsis.
Epigenetic reprogramming rewires transcription during the alternation of generations in Arabidopsis.
复制标题
表观遗传重编程在拟南芥的世代交替过程中重新连接转录。
DOI：
10.7554/elife.61894
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发表时间：
2021-01-25
期刊：
影响因子：
7.7
通讯作者：
Berger F
中科院分区：
文献类型：
--
作者：
Borg M;Papareddy RK;Dombey R;Axelsson E;Nodine MD;Twell D;Berger F
形态上不同的单倍体和二倍体生命形式之间的交替是大多数植物和藻类生命周期的一个定义特征，但管理这些转变的潜在分子机制仍不清楚。在这里，我们探讨了在拟南芥的生命形式转变过程中染色质可及性和表观遗传修饰之间的动态关系。二倍体到单倍体的生命形式转变是由H3K9me2的丢失和转座子相关顺式调控元件的DNA去甲基化所控制的。该事件与染色质可及性和转录重编程的显著变化相关。相比之下，H3K27me3在单倍体形式中的整体丢失形成了一个染色质可及性景观，该景观有望在受精后重新启动向二倍体生命的过渡。因此，不同的表观遗传重编程事件通过调节表观基因组的主要重组来重新连接转录，以指导显花植物的世代交替。开花植物的每个花粉粒都含有精子，其中含有形成新植物所需的一半基因，以及一个伴侣或营养细胞（VC），用于将精子传递给卵子。营养细胞和精子中的基因与它们所来自的植物的基因是相同的，那么这组相同的遗传信息如何产生如此不同的细胞呢？DNA和组蛋白，即包装和排列DNA的蛋白质，都可以通过一种称为甲基化的过程进行局部化学修饰。这些修饰的位置可以影响DNA中的遗传信息如何被读取以制造不同类型的细胞。利用甲基化等过程来调节基因的开启或关闭被称为表观遗传学。那么表观遗传学在植物花粉中扮演什么角色呢？为了回答这个问题，博格等人研究了拟南芥花粉的表观遗传学，拟南芥是一种被广泛研究的植物和常见的杂草。在营养细胞中，DNA甲基化与一个不同的甲基化标记（H3K9me2）一起丢失，该标记解锁了花粉运输精子所需的几个基因。相比之下，精子失去了一个完全不同的甲基化标记，称为H3K27me3，它解锁了一组不同的基因，一旦精子使卵子受精，这些基因有助于准备新植物的发育。通过这些不同的表观遗传变化，不同基因组的活性增加，这些基因对形成每种花粉细胞类型的功能很重要。这些结果揭示了DNA的丢失和组蛋白甲基化对植物通过花粉进行有性繁殖的重要性。这提供了对植物和其他相关生命形式进化的见解。了解植物繁殖也可能有助于通过提高作物产量来增加粮食产量。
Alternation between morphologically distinct haploid and diploid life forms is a defining feature of most plant and algal life cycles, yet the underlying molecular mechanisms that govern these transitions remain unclear. Here, we explore the dynamic relationship between chromatin accessibility and epigenetic modifications during life form transitions in Arabidopsis. The diploid-to-haploid life form transition is governed by the loss of H3K9me2 and DNA demethylation of transposon-associated cis-regulatory elements. This event is associated with dramatic changes in chromatin accessibility and transcriptional reprogramming. In contrast, the global loss of H3K27me3 in the haploid form shapes a chromatin accessibility landscape that is poised to re-initiate the transition back to diploid life after fertilisation. Hence, distinct epigenetic reprogramming events rewire transcription through major reorganisation of the regulatory epigenome to guide the alternation of generations in flowering plants. Each pollen grain from a flowering plant houses sperm, which contain half of the genes needed to make a new plant, and a companion or vegetative cell (VC) that serves to deliver sperm to the egg. The genes in the vegetative cell and those in the sperm are identical to the genes of the plant they come from, so how can this set of identical genetic information produce such different cells? Both DNA and histones, the proteins that pack and order DNA, can be chemically modified locally through a process called methylation. The location of these modifications can affect how genetic information in the DNA is read to make different types of cells. The use of processes like methylation to regulate whether genes are switched on or off is called epigenetics. So what role does epigenetics play in plant pollen? To answer this question, Borg et al. examined the epigenetics of pollen in Arabidopsis thaliana, a widely studied plant and common weed. In vegetative cells, DNA methylation is lost together with a different methylation mark (H3K9me2), which unlocks several genes needed for pollen to transport sperm. By contrast, sperm loses an entirely different methylation mark, called H3K27me3, which unlocks a different set of genes that help to prepare development of a new plant once sperm fertilizes the egg. Through these different set of epigenetic changes, activity increases at different groups of genes that are important for shaping the function of each pollen cell type. These results reveal how the loss of DNA and histone methylation are important for plants to reproduce sexually via pollen. This offers insights into the evolution of plants and other related life forms. Learning about plant reproduction may also help to increase food production by improving crop yields.