400 million years of faithfulness - how the transcriptional regulators LEUNIG and SEUSS co-evolved to become key factors of reproductive development in Arabidopsis thaliana

在陆地植物进化过程中，全基因组复制(WGD)发生得相当频繁，使得支配发育过程的基因网络得以扩大和重新布线。这可能有助于“老”基因的新表达模式的产生和对新基因的严格调控。这些分子进化过程被认为是新性状起源的先决条件。陆地植物有性繁殖提供了许多例子来了解新奇事物的分子起源，例如种子植物胚珠或被子植物心皮的进化创新。在ICIPS研究单位，我们建议分析一对转录辅阻遏子Leunig(LUG)和Seuss(SEU)的分子进化，这两个基因在花发育的几个方面都发挥着重要作用。有趣的是，它们在陆地植物出现之前就已经存在了，可能已经作为转录抑制因子发挥了作用。利用差异很大的ICIPS物种，我们的目标是阐明当经历了独立的WGD的不同植物谱系中存在许多基因网络重新布线的机会时，抑制子如何进化的一般问题。更具体地说，我们询问有关LUG和SEU同源物在苔藓、地钱、蕨类和种子植物中的数量和表达的问题，并分析各自蛋白质的蛋白质相互作用。此外，我们还将鉴定它们在非种子植物有性繁殖中的作用。利用这些方法，我们将解决这些辅抑制子是如何共同进化并被招募来转录调节性生殖器官发育的问题，开花植物如拟南芥。此外，我们与Günter Theiüen的实验室一起，建议通过生成与特定发育阶段相关的转录组数据并设计C-蕨类的基因编辑系统来建立蕨类植物Ceratopteris richardii(C-Fern)的遗传模型系统。

During land plant evolution whole genome duplications (WGDs) occurred rather frequently, allowing gene networks governing developmental processes to expand and rewire. This may have contributed to the generation of novel expression patterns for “old” genes and tight regulation of novel genes. These molecular evolutionary processes are thought to be a prerequisite for the origin of novel traits. Land plant sexual reproduction provides many examples to learn about the molecular origin of novelties, such as the evolutionary innovations of seed plant ovules or angiosperm carpels.Within the Research Unit ICIPS, we propose to analyze the molecular evolution of a pair of transcriptional corepressors LEUNIG (LUG) and SEUSS (SEU), which both play a major role in several aspects of flower development. Interestingly they were present already before the advent of land plants and possibly acted already as repressors of transcription. Using the widely divergent ICIPS species, we aim to shed light on the general questions on how repressors evolve when many opportunities for gene network rewiring exist in diverse plant lineages that underwent independent WGDs. More specifically, we ask questions regarding the number and expression of LUG and SEU homologs in mosses, liverworts, ferns, and seed plants, and we analyze the protein interactions of the respective proteins. Moreover, we will identify their function in sexual reproduction in non-seed plants. Using these approaches, we will address the question as to how these corepressors coevolved and were recruited to transcriptionally regulate sexual reproductive organ development flowering plants such as Arabidopsis thaliana. In addition, and together with the lab of Günter Theißen, we propose to establish the fern Ceratopteris richardii (C-fern) as a genetic model system by generating transcriptome data relevant to characterize defined stages of development and by devising a gene editing system for C-fern.