Flowering time, miRNA regulation and climatic adaptation: Variation in Brassica napus idiotypes under drought stress

开花时间是一个重要的适应性性状。由于开花时间和持续时间对其他适应性性状有着深远的影响，如对害虫的抗性和对高/低温或干旱等非生物胁迫的耐受性，因此假设潜在的调控网络之间存在串扰。虽然开花网络和压力信号通路是很好的研究，这两种途径之间的联系仍然留下悬而未决的问题，虽然重要的联系将作为非生物胁迫适应标记辅助育种计划的优秀标记。微RNA（micro-RNA，miRNA）是一类小分子调控RNA，在多种调控途径中发挥重要作用。已经建立了将miRNAs与发芽、开花和衰老以及对非生物胁迫的响应联系起来的关联。它们也是很有前途的相声信使候选人。虽然在模式植物中建立了miRNA研究，但在确定miRNA介导的作物性状调节的范围和作用方面仅取得了微小进展。通过挖掘基因组和转录组数据集，我们揭示了在一个A-基因组同源物的FRIGIDA（FRI），一个关键的花卉调节也牵连在非生物胁迫适应的miRNA结合位点。我们发现FRI的相应拷贝在抗旱的B中上调。rapa基因型在渗透胁迫下表达下调，而在干旱敏感基因型和不存在胁迫的情况下观察到下调。基于这种潜在的相互作用的中心开花调节因子FRI，miRNA和干旱胁迫反应，我们的目标是调查这种相互作用在不同的组织在B。在胁迫和非胁迫条件下对干旱胁迫表现出不同响应的油菜基因型。为此，我们将从植物生命周期中不同时间点的胁迫前后提取和测序miRNA。同时，选择的Bna.FRI同源物和其他潜在的miRNA靶标将通过qRT-PCR进行定量。表达模式将与开花和干旱反应方面的生理影响相关联，通过在大容器系统中进行详细的表型分析来评估，该系统允许在类似于田间土壤环境的条件下精确控制干旱胁迫。

The timing of flowering is an important adaptive trait. Because flowering time and duration have a profound influence on other adaptive traits, like resistance to pests and tolerance to abiotic stresses like high/low temperatures or drought, a crosstalk is assumed between the underlying regulatory networks. While the flowering network and stress signalling pathways are well-studied, links between the two pathways still leave open questions, although important links would serve as excellent markers for abiotic stress adaptation in marker-assisted breeding programs. Micro-RNAs (miRNA) are a class of small regulatory RNAs that have been found to play an important role in numerous regulatory pathways. Associations have been established linking miRNAs with germination, flowering and senescence as well as responses to abiotic stress. They are also promising candidates as crosstalk messengers. While miRNA research is established in model plants, only minor progress has been made in determining the scope and action of miRNA-mediated trait regulation in crops. By mining genomic and transcriptome datasets we revealed miRNA binding sites in an A-genome homologues of FRIGIDA (FRI), a key floral regulator also implicated in abiotic stress adaptation. We found the corresponding copy of FRI to be upregulated in a drought-resistant B. rapa genotype under osmotic stress, whereas down-regulation was observed in drought-sensitive genotypes and in the absence of stress. Based on this potential interaction of the central flowering regulator FRI, miRNA and drought stress responses, we aim to investigate this interaction within different tissues in B. napus genotypes that exhibit differential responses to drought stress under stressed and non-stressed conditions. For this purpose, we will extract and sequence miRNA from different time points during the plant lifecycle before and after stress application. At the same time, selected Bna.FRI homologues and other potential miRNA targets will be quantified by qRT-PCR. Expression patterns will be associated to physiological influences in terms of flowering and drought response, assessed by detailed phenotyping in a large-container system which allows exact control of drought stress under conditions resembling a field soil environment.