Computational Identification, Target Prediction, and Validation of Conserved miRNAs in Insulin Plant (Costus pictus...

Insulin plant (Costus pictus D. Don) is an economically important medicinal plant for the content of its high value secondary metabolites, bioactive compounds, and remarkable flowering features. MicroRNAs are a class of short (∼21 nucleotides), endogenous, noncoding RNA molecules that play a vital role in regulating gene expression. Here, we used a computer-based homology approach to identify conserved miRNAs in Transcribed Sequence Assemblies (TSA) of C. pictus. It led us to identify 42 miRNAs of 13 different families in C. pictus for the first time. Using quantitative polymerase chain reaction (qPCR) assays, we further confirmed the expression of 8 miRNAs (miR394, miR159b, miR166k, miR172, miR159f, miR166, miR144, and miR858) in young and mature leaf tissues. A total of 109 potential target genes of the identified miRNAs were subsequently predicted in rice (Oryza sativa L.) genome. The target genes encode transcription factors, enzymes, and various functional proteins involved in the regulation of several metabolic pathways. The findings in the present study lay the foundation for further research on miRNAs and miRNA-mediated gene regulation in this important medicinal plant.