Metabolic Profiling of Dendrobium officinale in Response to Precursors and Methyl Jasmonate.

Siyan Zheng,Yingpeng Zhu,Cheng Song,Chunyan Jiao,Qing Jin,Yi Lin,Yongping Cai

doi:10.3390/ijms19030728

Abstract

Alkaloids are the main active ingredients in the medicinal plant Dendrobium officinale. Based on the published genomic and transcriptomic data, a proposed terpenoid indole alkaloid (TIA) biosynthesis pathway may be present in D. officinale. In this study, protocorm-like bodies (PLBs) with a high-yielding production of alkaloids were obtained by the optimization of tryptophan, secologanin and methyl jasmonate (MeJA) treatment. The results showed that the total alkaloid content was 2.05 times greater than that of the control group when the PLBs were fed with 9 µM tryptophan, 6 µM secologanin and 100 µM MeJA after 36 days. HPLC analysis showed that strictosidine synthase (STR) activity also increased in the treated plants. A total of 78 metabolites were identified using gas chromatography-mass spectrometry (GC-MS) in combination with liquid chromatography-mass spectrometry (LC-MS) methods; 29 differential metabolites were identified according to the multivariate statistical analysis. Among them, carapanaubine, a kind of TIA, exhibited dramatically increased levels. In addition, a possible underlying process of the metabolic flux from related metabolism to the TIA biosynthetic pathway was enhanced. These results provide a comprehensive view of the metabolic changes related to alkaloid biosynthesis, especially TIA biosynthesis, in response to tryptophan, secologanin and MeJA treatment.

Highlights

Plants of the Dendrobium genus, especially Dendrobium officinale Kimura et Migo, are traditional Chinese medicinal herbs used for maintaining tonicity of the stomach and promoting body fluid production [1]
The principal component analysis (PCA) model depicted the sample groupings: all the control samples clustered together and were significantly separated from the treated samples. These results showed that tryptophan, secologanin and methyl jasmonate (MeJA) may strongly impact the D. officinale protocorm-like bodies (PLBs) metabolome
Our results showed a decrease in pelletierine, senkirkine, glucose, fructose and galactose, and an increase in tryptophan and carapanaubine, indicating that the flux change from related metabolism to the terpenoid indole alkaloid (TIA) biosynthetic pathway was induced by tryptophan, secologanin and MeJA

Summary

Introduction

Plants of the Dendrobium genus, especially Dendrobium officinale Kimura et Migo, are traditional Chinese medicinal herbs used for maintaining tonicity of the stomach and promoting body fluid production [1]. Previous studies have focused on characterizing alkaloid components in Dendrobium plants. Ever since the genome and transcriptome of D. officinale were sequenced, results have shown that D. officinale may contain terpenoid indole alkaloids (TIAs) [3,7,8,9]. A common precursor for all TIAs is strictosidine, which is assembled from two intermediates: tryptamine and secologanin. The former is synthesized from the indole pathway, while the latter is derived from the terpene biosynthetic pathway; both intermediates combine with each other by strictosidine synthase (STR) to form strictosidine [10,11]

Methods

Results

Conclusion