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

开花时间是一种重要的适应性性状。由于开花时间和持续时间对其他适应特性有深远的影响，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。虽然开花网络和逆境信号通路已经得到了很好的研究，但这两条途径之间的联系仍然是悬而未决的问题，尽管重要的联系将在标记辅助育种计划中作为非生物逆境适应的优秀标记。Micro-RNAs(MiRNA)是一类小分子调控RNA，已被发现在众多调控途径中发挥重要作用。已经建立了将miRNAs与种子萌发、开花和衰老以及对非生物胁迫的反应联系起来的联系。他们也很有希望成为相声信使的候选人。虽然miRNA的研究是在模式植物中建立的，但在确定miRNA介导的作物性状调控的范围和作用方面只取得了很小的进展。通过挖掘基因组和转录组数据集，我们发现了FRIGIDA的A基因组同源基因(FRi)中的miRNA结合位点，FRIGIDA是一个关键的花调节因子，也参与了非生物胁迫适应。我们发现，在渗透胁迫下，相应的FRi拷贝在抗旱型油菜中上调，而在干旱敏感和无胁迫时表达下调。基于中央开花调控因子Fri、miRNA和干旱胁迫反应的这种潜在的相互作用，我们旨在研究在胁迫和非胁迫条件下对干旱胁迫表现出不同反应的甘蓝型油菜不同组织中的这种相互作用。为此，我们将从胁迫处理前后植物生命周期的不同时间点提取miRNA并进行测序。同时，选定的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有关，通过在大容器系统中进行详细的表型分析来评估，该系统允许在类似田间土壤环境的条件下准确控制干旱胁迫。

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.