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Hybridization and reticulation as driving forces in the evolution of grasses from temperate regions (grass subfamily Pooideae)?

杂交和网状化是温带地区草类（草亚科早熟禾亚科）进化的驱动力？

基本信息

批准号：
194982876
负责人：
Professor Dr. Martin Röser
金额：
--
依托单位：
Lehrstuhl für Systematik und Biodiversität
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/194982876?language=en
关键词：
Hybridization reticulation driving forces evolution

项目摘要

The grass subfamily Pooideae (~3300 species) is characteristic of the Earth´s temperate climate zones. This plant group is extremely meaningful for humans, because it has evolved major crop plants like wheat, barley, rye and oat. It is significant therefore (1) to identify the evolutionary lineages present within this subfamily, (2) to clarify their interrelations and (3) to determine the temporal sequence how they originated. In the preceding project phase we achieved a dense coverage of genera for DNA sequence data from the plastid and nuclear genome (matK-trnK region, repetitive nuclear ribosomal ITS). The data were analysed in conjunction with morphological, chromosomal and biogeographical research results. This led to several far-reaching taxonomic changes including the discovery of the new tribe Duthieeae among the early diverging lineages of Pooideae, to altered circumscriptions and re-arrangements of major evolutionary lineages (tribes, subtribes). On the whole, the molecular phylogenetic information for parts of the subfamily Pooideae and the placement of many genera in the trees seem to be at odds with classifications based on morphology. Frequent past hybridisation, partly even between genera from different tribes (intertribe hybridisation) therefore was discussed as a potential explanation of these inconsistencies. To obtain direct evidence on the role of past hybridisation and reticulate evolution, this project will focus on the biparentally inherited nuclear genome. Nuclear single copy genes (SCGs) have been increasingly used in recent years to analyse hybrid processes, introgression in homoploids, diploid-polyploid relationships, thus finally evolutionary reticulation. These non-repetitive markers preserve the evolutionary history frequently much better than the ribosomal arrays since they are less prone to gene conversion, a process, in which one parental copy is replaced by the other. Building on our preliminary work on topoisomerase 6 (Topo6) and acetyl-CoA carboxylase 1 (Acc1), we will sequence 5 exon/intron regions of these SCGs, which already have been successfully tested in our previous studies, and 4 from other SCGs. We will focus on the widely unresolved early diverging lineages of Pooideae (tribes Stipeae, Duthieeae, etc.) and the large Aveneae/Poeae tribe complex. For our study, 70 and 190 representative taxa have been selected from these groups. Conventional Sanger method and Next Generation Sequencing (NGS) will be used to gather DNA information. The data set of the SCGs will be compared with the plastid matK-trnK and nuclear ITS data, which have already been generated for the taxonomically completely overlapping sample of taxa. This analysis of differently inherited (uniparentally vs. biparentally) and differently evolving DNA regions is expected to give for the first time direct, DNA-based evidence of hybrid processes and has a high potential in their reconstruction.

禾本科Pooideae（约3300种）是地球温带气候区的特征。这个植物群对人类来说非常有意义，因为它已经进化出小麦，大麦，黑麦和燕麦等主要作物。因此，（1）确定该亚科中存在的进化谱系，（2）澄清它们的相互关系和（3）确定它们如何起源的时间顺序是重要的。在前一个项目阶段，我们实现了一个密集的覆盖属的DNA序列数据从质体和核基因组（matK-trnK区，重复核核糖体ITS）。结合形态学、染色体和植物地理学研究结果对数据进行了分析。这导致了几个影响深远的分类学变化，包括在早熟禾亚科的早期分歧谱系中发现了新的族Duthieeae，改变了主要进化谱系（族，亚族）的环境和重新安排。总的来说，部分亚科Pooideae的分子系统发育信息和许多属在树中的位置似乎与基于形态学的分类不一致。频繁的过去杂交，部分甚至来自不同部落的属之间（部落间杂交），因此讨论了这些不一致的一个潜在的解释。为了获得过去杂交和网状进化的作用的直接证据，该项目将集中于双亲遗传的核基因组。近年来，核单拷贝基因（SCG）已越来越多地用于分析杂种过程，同源体中的渐渗，二倍体-多倍体关系，从而最终进化的网状结构。这些非重复性标记通常比核糖体阵列更好地保存进化历史，因为它们不太容易发生基因转换，这是一个过程，其中一个亲本拷贝被另一个替代。基于我们对拓扑异构酶6（Topo 6）和乙酰辅酶A羧化酶1（Acc 1）的初步研究，我们将对这些SCG的5个外显子/内含子区域进行测序，这些区域已经在我们以前的研究中成功测试，4个来自其他SCG。我们将集中在广泛未解决的早期分歧谱系的蒲亚科（部落Stipeae，Duthieeae等）。和大型的燕麦族/早熟禾族复合体。对于我们的研究，70和190代表类群已被选定从这些群体。将使用常规桑格方法和下一代测序（NGS）来收集DNA信息。的SCG的数据集将与质体matK-trnK和核ITS数据，这已经产生的分类学上完全重叠的样本的类群进行比较。这种对不同遗传（单亲与双亲）和不同进化的DNA区域的分析预计将首次提供直接的、基于DNA的杂交过程证据，并在其重建中具有很高的潜力。