Transcriptional Responses and Gentiopicroside Biosynthesis in Methyl Jasmonate-Treated Gentiana macrophylla Seedlings

PLoS One. 2016 Nov 16;11(11):e0166493. doi: 10.1371/journal.pone.0166493. eCollection 2016.

Abstract

Gentiana macrophylla, a medicinal plant with significant pharmacological properties, contains the bioactive compound gentiopicroside. Methyl jasmonate (MeJA) is an effective elicitor for enhancing the production of such compounds. However, little is known about MeJA-mediated biosynthesis of gentiopicroside. We investigated this phenomenon as well as gene expression profiles to determine the molecular mechanisms for MeJA-mediated gentiopicroside biosynthesis and regulation in G. macrophylla. Our HPLC results showed that Gentiana macrophylla seedlings exposed to MeJA had significantly higher concentrations of gentiopicroside when compared with control plants. We used RNA sequencing to compare transcriptional profiles in seedlings treated for 5 d with either 0 μmol L-1 MeJA (C) or 250 μmol L-1 MeJA (M5) and detected differentially expressed genes (DEGs). In total, 77,482 unique sequences were obtained from approximately 34 million reads. Of these, 48,466 (57.46%) sequences were annotated based on BLASTs performed against public databases. We identified 5,206 DEGs between the C and M5 samples, including genes related to the α-lenolenic acid degradation pathway, JA signaling pathway, and gentiopicroside biosynthesis. Expression of numerous enzyme genes in the glycolysis pathway was significantly up-regulated. Many genes encoding transcription factors (e.g. ERF, bHLH, MYB, and WRKY) also responded to MeJA elicitation. Rapid acceleration of the glycolysis pathway that supplies precursors for IPP biosynthesis and up-regulates the expression of enzyme genes in that IPP pathway are probably most responsible for MeJA stimulation of gentiopicroside synthesis. Our qRT-PCR results showed that the expression profiles of 12 gentiopicroside biosynthesis genes were consistent with the RNA-Seq data. These results increase our understanding about how the gentiopicroside biosynthesis pathway in G. macrophylla responds to MeJA.

MeSH terms

  • Acetates / pharmacology*
  • Biosynthetic Pathways / drug effects
  • Biosynthetic Pathways / genetics*
  • Cyclopentanes / metabolism
  • Cyclopentanes / pharmacology*
  • Gene Expression Regulation, Plant / drug effects
  • Genes, Plant
  • Gentiana / drug effects
  • Gentiana / genetics*
  • Glycolysis / drug effects
  • Iridoid Glucosides / metabolism*
  • Molecular Sequence Annotation
  • Oxylipins / metabolism
  • Oxylipins / pharmacology*
  • Real-Time Polymerase Chain Reaction
  • Reproducibility of Results
  • Secondary Metabolism / drug effects
  • Secondary Metabolism / genetics
  • Seedlings / drug effects
  • Seedlings / genetics*
  • Sequence Analysis, RNA
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic / drug effects*
  • Transcriptome
  • Up-Regulation / drug effects
  • Up-Regulation / genetics
  • alpha-Linolenic Acid / metabolism

Substances

  • Acetates
  • Cyclopentanes
  • Iridoid Glucosides
  • Oxylipins
  • Transcription Factors
  • alpha-Linolenic Acid
  • gentiopicroside
  • jasmonic acid
  • methyl jasmonate

Grants and funding

This work was funded by the Natural Science Foundation of Shaanxi Province, China (2014JQ3107) and the Fundamental Research Funds for the Central Universities (GK201302043). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.