Identification and Characterization of <i>Salvia miltiorrhizain</i> miRNAs in Response to Replanting Disease

<div><p>Replanting disease is a major factor limiting the artificial cultivation of the traditional Chinese medicinal herb <i>Salvia miltiorrhiza</i>. At present, little information is available regarding the role of miRNAs in response to replanting disease. In this study, two small RNA libraries obtained from first-year (FPR) and second-year plant (SPR) roots were subjected to a high-throughput sequencing method. Bioinformatics analysis revealed that 110 known and 7 novel miRNAs were annotated in the roots of <i>S</i>. <i>miltiorrhiza</i>. Moreover, 39 known and 2 novel miRNAs were identified and validated for differential expression in FPR compared with SPR. Thirty-one of these miRNAs were further analyzed by qRT-PCR, which revealed that 5 miRNAs negatively regulated the expression levels of 7 target genes involved in root development or stress responses. This study not only provides novel insights into the miRNA content of <i>S</i>. <i>miltiorrhiza</i> in response to replanting disease but also demonstrates that 5 miRNAs may be involved in these responses. Interactions among the differentially expressed miRNAs with their targets may form an important component of the molecular basis of replanting disease in <i>S</i>. <i>miltiorrhiza</i>.</p>