miRNA and their putative targets in Andrographis paniculata

Abstract

miRNAs are non-coding RNAs participate in post transcriptional and translational regulation of genes involved in various biological activities. Besides, miRNAs are also involved in plant protection against invading viruses, bacteria, fungi etc. In plants, RNA polymerase II transcribes primary miRNAs (pri-miRNAs) of heterogenous length. These molecules are first sequentially cleaved by DICER LIKE 1 (DCL1) in the nucleus where a processing complex is formed. A double stranded miRNA/miRNA* duplex is emerged by processing complex. This is O-methylated by Hua-Enhancer1 (HEN1) and further exported to the cytoplasm by exporting 5 homolog, HASTY. Mature or pre-miRNA are formed after degradation of miRNA* by 3′–5′ exoribonucleases. Mature miRNAs are exported to cytoplasm by HASTY (HST) and loaded on major player of pathway, ARGONAUTE (AGO) forming RNA-induced silencing complex (RISC) facilitating interaction with target RNAs. These complex actions negatively regulate target gene expression by either translation inhibition or a target transcript cleavage. Recently, miRNA regulation has been reported in secondary metabolite production and abiotic or biotic stresses.