Methyl jasmonate induces the regulation of protostane triterpene biosynthesis by microRNAs in Alisma orientale.

Protostane triterpenes are medicinally important components found in members of the Alismataceae botanical family, notably Alisma orientale. Methyl jasmonate (MeJA) is known to regulate protostane triterpene biosynthesis in A. orientale, but the microRNA (miRNA) mechanism underlying MeJA response to promote triterpene biosynthesis remains unknown. In this study, we conducted miRNA sequencing analysis after MeJA induction in A. orientale to uncover the role of miRNAs in protostane triterpene biosynthesis. We identified 222 known miRNAs and 379 novel miRNAs, including 16 differentially expressed miRNAs (DEMs) between control and MeJA-treated leaf samples. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment analysis, four DEMs and eight miRNA target genes were significantly enriched in the triterpene biosynthesis pathway. Integrated analysis of the transcriptome and miRNAome revealed a negative expression pattern between miRNAs and their target genes. We then constructed a regulatory network of miRNA-target gene relationships involved in the triterpene biosynthesis pathway. We found miRNAs may be involved in the response of A. orientale to exogenous MeJA by regulating the expression of key biosynthesis enzymes, leading to increased accumulation of medically important protostane triterpenes.