Identification of putative miRNAs from Expressed Sequence Tags of Gnetum gnemon L. and their cross-kingdom targets in human

Wild edible plants are often found to be rich sources of nutrients and medicinally beneficial compounds with pharmacological activities. Gnetum gnemon is a nutritionally important plant and a popular food source in parts of Assam and North-East India. Various microRNAs (miRNAs) have been recently identified in many plants; however, there are no records of identification of miRNAs in any species of Gnetum. The prediction of miRNA-target associations in G. gnemon is an important step to facilitate functional genomics studies in this species. In the present study, all known miRNAs from plants available in public domain were used to search for the conserved G. gnemon miRNA homologues in publicly accessible expressed sequence tags (ESTs) in NCBI database. An aggregate of 20 new potential miRNAs belonging to two diverse miRNA families (miR399 and miR5021) were identified through a homology-based search by following stringent filtering criteria. To investigate the potential cross-kingdom effects of the identified miRNAs, we further identified the putative target genes of G. gnemon miRNAs in human transcriptome and analyzed them against the NCBI non-redundant protein database. The KEGG analysis of the target genes indicated that these genes were involved in different metabolic pathways such as caffeine metabolism, drug metabolism, and nitrotoluene degradation. The target genes of G. gnemon miRNAs in humans were found to be associated with various disorders of both hereditary and non-hereditary origin. These results could help to shed new light on understanding of miRNA-mRNAs functional networks in this species and its potential use as a small RNA-based therapy against some human diseases.