Hazels (Corylus spp.) are economically important nut-producing species in which ovule development determines seed plumpness, one of the key parameters reflecting nut quality. microRNAs (miRNAs) play important roles in RNA silencing and the post-transcriptional regulation of gene expression. However, very little is currently known regarding the miRNAs involved in regulating ovule growth and development. In this study, we accordingly sought to determine the important miRNAs involved in ovule development and growth in hazel. We examined ovules at four developmental stages, namely, ovule formation (Ov1), early ovule growth (Ov2), rapid ovule growth (Ov3), and ovule maturity (Ov4). On the basis of small RNA and mRNA sequencing using the Illumina sequencing platform, we identified 970 miRNAs in hazel, of which 766 and 204 were known and novel miRNAs, respectively. In Ov1-vs-Ov2, Ov1-vs-Ov3, Ov1-vs-Ov4, Ov2-vs-Ov3, Ov2-vs-Ov4, and Ov3-vs-Ov4 paired comparisons, 471 differentially expressed microRNAs (DEmiRNAs) and their 3117 target differentially expressed messenger RNAs (DEmRNAs) formed 11,199 DEmiRNA/DEmRNA pairs, with each DEmiRNA changing the expression of an average of 6.62 target mRNAs. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of all DEmRNAs revealed 29 significantly enriched KEGG pathways in the six paired comparisons, including protein export (ko03060), fatty acid elongation (ko00062), starch and sucrose metabolism (ko00500), fatty acid biosynthesis (ko00061), and amino sugar and nucleotide sugar metabolism (ko00520). Our results indicate that DEmiRNA/DEmRNA pairs showing opposite change trends were related to stress tolerance, embryo and seed development, cell proliferation, auxin transduction, and the biosynthesis of proteins, starch, and fats may participate in ovule growth and development. These findings contribute to a better understanding of ovule development at the level of post-transcriptional regulation, and lay the foundation for further functional analyses of hazelnut ovule growth and development.

中文翻译：

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使用榛树中的高通量测序鉴定调节胚珠发育的重要候选microRNA / mRNA对。

榛子（Corylus spp。）是经济上重要的坚果生产品种，其中胚珠发育决定种子的饱满度，这是反映坚果品质的关键参数之一。microRNA（miRNA）在RNA沉默和基因表达的转录后调控中发挥重要作用。但是，目前对于参与调控胚珠生长和发育的miRNA知之甚少。因此，在这项研究中，我们试图确定与榛子胚珠发育和生长有关的重要miRNA。我们检查了四个发育阶段的胚珠，即胚珠形成（Ov1），早期胚珠生长（Ov2），快速胚珠生长（Ov3）和胚珠成熟度（Ov4）。在使用Illumina测序平台进行小RNA和mRNA测序的基础上，我们在榛树中鉴定了970个miRNA，其中766和204个是已知的和新颖的miRNA，分别。在Ov1-vs-Ov2，Ov1-vs-Ov3，Ov1-vs-Ov4，Ov2-vs-Ov3，Ov2-vs-Ov4和Ov3-vs-Ov4配对比较中，有471个差异表达的microRNA（DEmiRNA）及其3117目标差异表达的信使RNA（DEmRNA）形成了11,199个DEmiRNA / DEmRNA对，每个DEmiRNA改变了平均6.62个目标mRNA的表达。京都基因与基因组百科全书（KEGG）对所有DEmRNA的富集分析显示，在六对配对比较中29种显着富集的KEGG途径，包括蛋白质输出（ko03060），脂肪酸延伸率（ko00062），淀粉和蔗糖代谢（ko00500），脂肪酸生物合成（ko00061），以及氨基糖和核苷酸糖代谢（ko00520）。我们的结果表明，显示相反变化趋势的DEmiRNA / DEmRNA对与胁迫耐受性，胚胎和种子发育有关，细胞增殖，生长素转导以及蛋白质，淀粉和脂肪的生物合成可能参与胚珠的生长和发育。这些发现有助于在转录后调控水平上更好地了解胚珠的发育，并为进一步分析榛子胚珠的生长和发育奠定了基础。