The evolution of RNA helicases and their roles for plant sexual and apomictic reproduction

高等植物采用不同的策略来确保成功繁殖，包括种子的有性和无性形成（无融合生殖）。与有性生殖不同，无融合生殖产生克隆后代。利用无融合生殖技术生产作物种子具有巨大的潜力，因为上级基因型可以在后代中保持。虽然无融合生殖在主要作物中自然不存在，但无融合生殖的工程化仍然是一个挑战。这是因为，尽管从科学和应用的角度来看，高度的兴趣，允许无融合生殖建立和无融合生殖的分子程序的进化过程仍然没有得到很好的理解，迄今为止，越来越多的证据表明，一个复杂的基因调控程序严格控制生殖谱系的发展。无融合生殖的基础可能是性途径的失调。一致的，我们现在确定了进一步的证据，细胞周期控制，转录和转录后调控的差异，比较转录组分析属Boechera有性和无融合生殖加入。重要的是，发现了新的无融合生殖候选基因，可能与控制有性生殖的基因有关。此外，先前已经提出了RNA解旋酶在调节无融合生殖中的意义。重要的是，携带MNEME（MEM）突变等位基因的植物在拟南芥中显示无融合生殖的元件。我们现在确定了这个基因家族的其他成员，这些基因突变会导致生殖发育过程中的缺陷。为了进一步深入了解RNA解旋酶的作用，为无融合生殖和它们的进化方面，我们测序了几个有性和无融合生殖的Boechera加入等位基因变体。与不同RNA解旋酶对生殖的重要性一致，不同的RNA解旋酶表现出等位基因变体的明显分歧。虽然解旋酶，被认为是至关重要的发育过程中表现出很小的变化，更大的等位基因的分歧，包括MEM，可能是重要的无融合生殖。拟议项目的目的是获得更全面的见解无融合生殖的基因调控基础，特别是RNA解旋酶在这一过程中的作用。为此，将整合不同的方法以（I）将转录分析扩展到配子发生的早期阶段，以加深我们对有性与无融合生殖Boechera中基因表达调控的理解，（II）拓宽所选RNA解旋酶的功能分析，重点是鉴定突变体中无融合生殖的特征，和（III）通过用来自有性生殖和无融合生殖的Boechera的等位基因变体补充突变体系来测试来自无融合生殖的等位基因变体的功能含义。这项研究将显着有助于了解的分子过程中，管理有性生殖和无融合生殖的植物及其进化的各个方面。

Higher plants employ different strategies to ensure successful reproduction, including sexual and asexual formation of seeds (apomixis). Unlike sexual reproduction, apomixis gives rise to clonal offspring. Harnessing of apomixis for crop seed production has outstanding potential, as superior genotypes could be maintained in subsequent generations. While apomixis is naturally not represented in major crops, engineering of apomixis remains a challenge. This is the case, as despite high interest from scientific as well as applied perspectives, the evolutionary processes that allowed apomixis to establish and the molecular programs governing apomictic reproduction are still not well understood to date.Increasing evidence suggests that a complex gene regulatory program tightly controls the development of reproductive lineages. And the basis of apomixis is likely a deregulation of the sexual pathway. Consistently, we now identified further evidence for differences in cell cycle control, transcriptional and posttranscriptional regulation by comparative transcriptome analysis of sexual and apomictic accessions of the genus Boechera. Importantly, new candidate genes for apomixis were uncovered that presumably relate to genes controlling sexual reproduction. Moreover, implications for RNA helicases in regulation of apomixis have previously been suggested. Importantly, plants carrying mutant alleles of MNEME (MEM) show an element of apomixis in Arabidopsis. We now identified additional members of this gene family, for which mutations lead to defects during reproductive development. To gain further insights into the roles of RNA helicases for apomixis and into aspects of their evolution, we sequenced allelic variants of several sexual and apomictic Boechera accessions. In line with the importance of different RNA helicases for reproduction, different RNA helicases showed distinct divergence of allelic variants. While helicases that are supposedly crucial for developmental processes show little variation, greater allelic divergence in others, including MEM, might be of importance for apomixis. The aim of the proposed project is to gain more comprehensive insights into the gene regulatory basis of apomixis and in particular the roles of RNA helicases in this process. To this aim different approaches will be integrated to (I) extend transcriptional analysis to early stages of gametogenesis to deepen our understanding of the regulation of gene expression in sexual versus apomictic Boechera, to (II) broaden functional analysis of selected RNA helicases with emphasis on the identification of features of apomixis in mutants, and (III) by testing functional implications of allelic variants from apomicts by complementing mutant lines with allelic variants from sexual and apomictic Boechera. This study will significantly contribute to an understanding of the molecular processes governing sexual and apomictic plant reproduction and aspects of their evolution.