Cold acclimation is crucial for the overwintering process of plants. Cold deacclimation is also important for plant survival in winter, which results in loss of freezing tolerance and initiation of growth. MicroRNAs (miRNAs) play crucial roles in regulating various physiological activities including cold response in plants. However, there is no study on miRNAs and their target genes in response to cold deacclimation in a cold-tolerant crop – barley (Hordeum vulgare L.). Here, we performed high-throughput sequencing of miRNAs of leaves during the cold deacclimation process using two barley cultivars with contrasting cold tolerance (Nure, tolerant and Tremois, sensitive). We found a total of 36 known and 267 novel miRNAs, including 12 known and 112 novel ones that are differentially expressed during cold deacclimation. The number of detected differentially expressed miRNAs was larger in Nure than that in Tremois, and the expression profile of miRNAs was dramatically different between Nure and Tremois. Moreover, we identified 13 known and 97 novel miRNAs, which have putative target genes during cold deacclimation. The putative targets of the novel miRNAs included genes encoding C-repeat binding factor (CBF) transcription factors, phytohormones, antioxidant, osmopretectant and flower development. Our results suggest that barley miRNAs respond quickly to cold deacclimation, and the larger number of miRNAs differentially expressed in the cold tolerant cv. Nure indicating that miRNAs might play an important role in the process of deacclimation. It sets a solid foundation for future studies and breeding programs on low temperature tolerance in barley.

中文翻译：

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鉴定用于大麦冷脱驯化的新型 microRNA

冷驯化对于植物的越冬过程至关重要。寒冷去驯化对植物在冬季的生存也很重要，这会导致失去抗冻性和开始生长。MicroRNAs (miRNAs) 在调节包括植物冷反应在内的各种生理活动中起着至关重要的作用。然而，目前还没有针对耐寒作物大麦 (Hordeum vulgare L.) 冷脱驯的 miRNA 及其靶基因的研究。在这里，我们使用两个具有对比冷耐受性的大麦品种（Nure，耐受性和 Tremois，敏感性）在冷去驯化过程中对叶子的 miRNA 进行了高通量测序。我们共发现了 36 种已知和 267 种新型 miRNA，其中包括 12 种已知和 112 种在冷脱驯化过程中差异表达的新型 miRNA。在 Nure 中检测到的差异表达 miRNA 的数量比在 Tremois 中多，并且 Nure 和 Tremois 之间的 miRNA 表达谱存在显着差异。此外，我们确定了 13 个已知和 97 个新的 miRNA，它们在冷脱驯化过程中具有推定的靶基因。新型 miRNA 的假定靶标包括编码 C-重复结合因子 (CBF) 转录因子、植物激素、抗氧化剂、渗透保护剂和花发育的基因。我们的结果表明大麦 miRNA 对冷脱驯化反应迅速，并且在耐寒 cv. 中差异表达的 miRNA 数量较多。Nure 表明 miRNA 可能在去驯化过程中发挥重要作用。它为大麦耐低温性的未来研究和育种计划奠定了坚实的基础。