Department of Plant and Microbial Biology & Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, CH-8008, Zurich, Switzerland.
Area of Plant Physiology, Department of Organisms and Systems Biology, University of Oviedo, c) Catedrático R Uría s/n, 33071, Oviedo, Spain.
Plant Physiol Biochem. 2020 Mar;148:302-311. doi: 10.1016/j.plaphy.2020.01.021. Epub 2020 Jan 18.
Apomixis was originally defined as the replacement of sexual reproduction by an asexual process that does not involve fertilization but, in angiosperms, it is often used in the more restricted sense of asexual reproduction through seeds. In ferns, apomixis combines the production of unreduced spores (diplospory) and the formation of sporophytes from somatic cells of the prothallium (apogamy). The genes that control the onset of apogamy in ferns are largely unknown. In this study, we describe the gametophyte transcriptome of the apogamous fern Dryopteris affinis ssp. affinis using an RNA-Seq approach to compare the gene expression profiles of one- and two-dimensional gametophytes, the latter containing apogamic centers. After collapsing highly similar de novo transcripts, we obtained 166,191 unigenes, of which 30% could be annotated using public databases. Multiple quality metrics indicate a good quality of the de novo transcriptome with a low level of fragmentation. Our data show a total of 10,679 genes (6% of all genes) to be differentially expressed between gametophytes of filamentous (one-dimensional) and prothallial (two-dimensional) architecture. 6,110 genes were up-regulated in two-dimensional relative to one-dimensional gametophytes, some of which are implicated in the regulation of meristem growth, auxin signaling, reproduction, and sucrose metabolism. 4,570 genes were down-regulated in two-dimensional versus one-dimensional gametophytes, which are enriched in stimulus and defense genes, as well as genes involved in epigenetic gene regulation and ubiquitin degradation. Our results provide insights into free-living gametophyte development, focusing on the filamentous-to-prothallus growth transition, and provide a useful resource for further investigations of asexual reproduction.
无融合生殖最初被定义为一种无性过程，取代了有性生殖，该过程不涉及受精，但在被子植物中，它通常被更狭义地用于通过种子进行无性繁殖。在蕨类植物中，无融合生殖结合了未减数孢子（双孢子）的产生和从原叶体体细胞形成孢子体（无配子生殖）。控制蕨类植物无配子生殖开始的基因在很大程度上是未知的。在这项研究中，我们使用 RNA-Seq 方法描述了无融合生殖蕨类植物细齿贯众 ssp 的配子体转录组。affinis 比较了一维和二维配子体的基因表达谱，后者包含无配子生殖中心。在折叠高度相似的从头转录本后，我们获得了 166191 个 unigenes，其中 30%可以使用公共数据库进行注释。多种质量指标表明，从头转录组具有良好的质量，碎片化程度低。我们的数据显示，在丝状（一维）和原叶体（二维）结构的配子体之间，共有 10679 个基因（所有基因的 6%）表达差异。与一维配子体相比，二维配子体中有 6110 个基因上调，其中一些基因参与分生组织生长、生长素信号转导、繁殖和蔗糖代谢的调节。在二维与一维配子体相比，有 4570 个基因下调，这些基因富集在刺激和防御基因，以及涉及表观遗传基因调控和泛素降解的基因。我们的研究结果提供了对自由生活配子体发育的深入了解，重点关注丝状到原叶体生长的转变，并为进一步研究无性繁殖提供了有用的资源。
