Sweet potato (Ipomoea batatas L.) is a food consumed worldwide, an industrial raw material and new energy crop. The storage root is the most economical part of the crop. However, the mechanism of storage root initiation and development is still unclear. In this study, conserved and novel miRNAs during storage root development were identified by high-throughput sequencing technology by constructing small RNA libraries from sweet potato fibrous roots (F) and storage roots at four different developmental stages (storage roots with different diameters: 1 cm, D1; 3 cm, D3; 5 cm, D5 and 10 cm, D10). A total of 61 known miRNAs and 471 novel miRNAs were identified. In addition, 145 differentially expressed miRNAs were identified in the F library compared with the four storage root libraries, with 30 known miRNAs and 115 novel miRNAs. Moreover, the targets of the differentially expressed miRNAs were predicted and their network was further investigated by GO analysis using our previous transcriptome data. The GO analysis revealed that antioxidant activity and binding process were the most enriched terms of the target genes. The secondary structure and expression of six candidate miRNAs including three conserved miRNAs and three novel miRNAs were investigated and their predicted targets were validated by qRT-PCR. The results showed that the expression levels of the miRNAs were all consistent with the sequencing data. Most of the miRNAs and their corresponding targets had obvious negative correlations. This study contributed to elucidating the potential miRNA mediated regulatory mechanism of storage root development in sweet potato. The specific differentially expressed miRNAs in sweet potato storage roots can be used to breed high-yield sweet potatoes and other tuberous root crops.

中文翻译：

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高通量测序鉴定与甘薯贮藏根发育相关的候选miRNA

甘薯（Ipomoea batatas L.）是世界范围内消费的粮食、工业原料和新能源作物。贮藏根是作物中最经济的部分。然而，贮藏根萌生和发育的机制尚不清楚。本研究从甘薯须根（F）和四个不同发育阶段（不同直径的贮藏根：1 cm）的贮藏根构建小RNA文库，通过高通量测序技术鉴定贮藏根发育过程中的保守和新型miRNA。 ，D1；3 厘米，D3；5 厘米，D5 和 10 厘米，D10）。共鉴定出 61 种已知 miRNA 和 471 种新型 miRNA。此外，与四个存储根库相比，F 库中鉴定出 145 个差异表达的 miRNA，其中 30 个已知 miRNA 和 115 个新 miRNA。而且，预测了差异表达的 miRNA 的靶标，并使用我们之前的转录组数据通过 GO 分析进一步研究了它们的网络。GO分析显示抗氧化活性和结合过程是靶基因中最丰富的术语。研究了六个候选 miRNA 的二级结构和表达，包括三个保守的 miRNA 和三个新的 miRNA，并通过 qRT-PCR 验证了它们的预测目标。结果表明，miRNAs的表达水平均与测序数据一致。大多数miRNA与其对应的靶标具有明显的负相关。该研究有助于阐明甘薯贮藏根发育的潜在miRNA介导的调控机制。