Integration of full-length transcriptomics and targeted metabolomics to identify benzylisoquinoline alkaloid biosynthetic genes in Corydalis yanhusuo

Dingqiao Xu,Hanfeng Lin,Yuping Tang,Lu Huang,Yucheng Zhao,Jian Xu,Sihui Nian

doi:10.1038/s41438-020-00450-6

Abstract

Corydalis yanhusuo W.T. Wang is a classic herb that is frequently used in traditional Chinese medicine and is efficacious in promoting blood circulation, enhancing energy, and relieving pain. Benzylisoquinoline alkaloids (BIAs) are the main bioactive ingredients in Corydalis yanhusuo. However, few studies have investigated the BIA biosynthetic pathway in C. yanhusuo, and the biosynthetic pathway of species-specific chemicals such as tetrahydropalmatine remains unclear. We performed full-length transcriptomic and metabolomic analyses to identify candidate genes that might be involved in BIA biosynthesis and identified a total of 101 full-length transcripts and 19 metabolites involved in the BIA biosynthetic pathway. Moreover, the contents of 19 representative BIAs in C. yanhusuo were quantified by classical targeted metabolomic approaches. Their accumulation in the tuber was consistent with the expression patterns of identified BIA biosynthetic genes in tubers and leaves, which reinforces the validity and reliability of the analyses. Full-length genes with similar expression or enrichment patterns were identified, and a complete BIA biosynthesis pathway in C. yanhusuo was constructed according to these findings. Phylogenetic analysis revealed a total of ten enzymes that may possess columbamine-O-methyltransferase activity, which is the final step for tetrahydropalmatine synthesis. Our results span the whole BIA biosynthetic pathway in C. yanhusuo. Our full-length transcriptomic data will enable further molecular cloning of enzymes and activity validation studies.

Highlights

We generated the first full-length transcriptome for C. yanhusuo and investigated the transcripts related to Benzylisoquinoline alkaloids (BIAs) biosynthesis in both leaf and tuber tissue of C. yanhusuo by combining single-molecule real-time (SMRT) and second-generation sequencing (SGS) technologies
We expected that the external application of methyl jasmonate (MeJA) would increase the expression of BIA biosynthetic genes, and the fold changes shown in Fig. S10 indicate the relevance of these genes to alkaloid bioproduction
Such inference is based on the following presumptions: (i) no other genes are responsible for BIA biosynthesis, (ii) BIAs are locally synthesized in the tubers instead of being transported there, and (iii) BIAs do not undergo automatic degradation in the leaf tissue

Summary

Introduction

T. Wang is a medicinal herb in the Corydalis genus of the Papaveraceae family. Its dried tubers (called “Yan-Hu-Suo” or “Yuan-Hu”) are frequently used as an important therapeutic agent, with well-recorded efficacy in promoting blood circulation, enhancing energy, and providing analgesia[1]. Recent pharmacological research has found that active compounds in C. yanhusuo can inhibit tumor cell proliferation[2]; attenuate acute, inflammatory and neuropathic pain[1]; reduce drug addiction[3,4]; and treat cardiovascular diseases[5,6,7]. Owing to the low productivity of tubers and the short life cycle of C. yanhusuo, plant material sources are limited, greatly impeding its further application. Little is known about the biosynthetic pathways of active compounds in C

Methods

Results

Conclusion