Transcriptomes of Podophyllum hexandrum unravel candidate miRNAs and their association with the biosynthesis of secondary metabolites

Abstract

Podophyllotoxin is a high value metabolite having anticancerous activity and procured from a medicinal plant Podophyllum hexandrum. The escalating demand for podophyllotoxin necessitates development of alternate production platforms. Cell cultures have been tried in the past, however, podophyllotoxin yields were very low (0.3%). Multiple genes of biosynthetic pathway have been correlated with podophyllotoxin content. Understanding regulation of podophyllotoxin is, therefore, essential to design a suitable genetic intervention strategy. Six potential miRNAs were identified in NGS transcriptomes of P. hexandrum for which eight potential mRNA targets were discerned. The identified miRNAs and their mRNA targets (UDP glycosyltransferase, flavonol synthase, glyceraldehyde 3-phosphate dehydrogenase, peroxidase, malate dehydrogenase, phosphoenolpyruvate carboxylase, WRKY 37 and MYBF1 transcription factors) were further tested for any correlation through qRT-PCR. miR396b, miR2673a, miR828b and miR2910 established negative correlation with their mRNA targets through downregulation via complementary miRNA:mRNA base pairing. This is the first report on identification, characterisation, validation and expression analysis of miRNAs and their targets in P. hexandrum.