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MicroRNAs (miRNAs) are small non-protein-coding RNAs that regulate gene expression in many eukaryotes. Next-generation sequencing of small RNAs (small RNA-seq) is central to the discovery and annotation of miRNAs. Newly annotated miRNAs and their longer precursors encoded byMIRNAloci are typically submitted to databases such as the miRBase microRNA registry following the publication of a peer-reviewed study. However, genome-wide scans using small RNA-seq data often yield high rates of false-positiveMIRNAannotations, highlighting the need for more robust validation methods. miRScore was developed as an independent and efficient tool for evaluating newMIRNAannotations using sRNA-seq data. miRScore combines structural and expression-based analyses to provide rapid and reliable validation of newMIRNAannotations. By providing users with detailed metrics and visualization, miRScore enhances the ability to assess confidence inMIRNAannotations. miRScore has the potential to advance the overall quality ofMIRNAannotations by improving accuracy of new submissions to miRNA databases and serving as a resource for re-evaluating existing annotations. 

Abstract Trans-species RNA interference (RNAi) occurs naturally when small RNAs (sRNAs) silence genes in species different from their origin. This phenomenon has been observed between plants and various organisms including fungi, animals and other plant species. Understanding the mechanisms used in natural cases of trans-species RNAi, such as sRNA processing and movement, will enable more effective development of crop protection methods using host-induced gene silencing (HIGS). Recent progress has been made in understanding the mechanisms of cell-to-cell and long-distance movement of sRNAs within individual plants. This increased understanding of endogenous plant sRNA movement may be translatable to trans-species sRNA movement. Here, we review diverse cases of natural trans-species RNAi focusing on current theories regarding intercellular and long-distance sRNA movement. We also touch on trans-species sRNA evolution, highlighting its research potential and its role in improving the efficacy of HIGS.