Transcriptome Mining of MicroRNAs Involved in Terpenoid Biosynthesis and Phylogenetic Analysis in Lamiaceae Species

Despite the importance of the regulatory role of miRNAs, their effect on terpenoids production is still poorly understood. Especially, the regulation of terpenoids biosynthesis by miRNAs in medicinal plants has a proper potential to be investigated. Since many of the known miRNAs are conserved, the prediction of plausible miRNAs is a fast, cheap, and desirable method that can be used as a screening tool to gain initial knowledge of species potential. Here, the transcriptomic data of a number of the Lamiaceae species were explored to identify miRNAs and target genes related to the terpenoids biosynthesis. Based on the results, miR1127, miR1128, miR1133, miR1436 and miR5021 were found in different species, indicating that they are likely specific to the Lamiaceae family. The highest number of predicted miRNAs involved in terpenoids biosynthesis were obtained in Hyssopus officinalis and Lavadula angustifolia. However, H. officinalis showed more diversity in terpenoid biosynthesis pathways, miRNA families, and predicted targets, suggesting that it may have developed a special adaptive strategy to produce diverse terpenoids through miRNA-mediated regulation. Additionally, the phylogenetic trees based on the similarities of the precursor nucleotide sequence of miRNAs manifested that many of the trees reliably recovered the phylogeny of the Lamiaceae family, in turn representing the effectiveness of miRNAs in determining the phylogenetic relationships of the species of the same family. In conclusion, the present research provides a new foundation for investigating the function of miRNAs to enrich the pathways of terpenoids biosynthesis, and their effects on determining the evolutionary relationships of species.