Illuminating the biosynthesis pathway genes involved in bioactive specific monoterpene glycosides in Paeonia veitchii Lynch by a combination of sequencing platforms.

BACKGROUND: Paeonia veitchii Lynch, a well-known herb from the Qinghai-Tibet Plateau south of the Himalayas, can synthesize specific monoterpene glycosides (PMGs) with multiple pharmacological activities, and its rhizome has become an indispensable ingredient in many clinical drugs. However, little is known about the molecular background of P. veitchii, especially the genes involved in the biosynthetic pathway of PMGs. RESULTS: A corrective full-length transcriptome with 30,827 unigenes was generated by combining next-generation sequencing (NGS) and single-molecule real-time sequencing (SMRT) of six tissues (leaf, stem, petal, ovary, phloem and xylem). The enzymes terpene synthase (TPS), cytochrome P450 (CYP), UDP-glycosyltransferase (UGT), and BAHD acyltransferase, which participate in the biosynthesis of PMGs, were systematically characterized, and their functions related to PMG biosynthesis were analysed. With further insight into TPSs, CYPs, UGTs and BAHDs involved in PMG biosynthesis, the weighted gene coexpression network analysis (WGCNA) method was used to identify the relationships between these genes and PMGs. Finally, 8 TPSs, 22 CYPs, 7 UGTs, and 2 BAHD genes were obtained, and these putative genes were very likely to be involved in the biosynthesis of PMGs. In addition, the expression patterns of the putative genes and the accumulation of PMGs in tissues suggested that all tissues are capable of biosynthesizing PMGs and that aerial plant parts could also be used to extract PMGs. CONCLUSION: We generated a large-scale transcriptome database across the major tissues in P. veitchii, providing valuable support for further research investigating P. veitchii and understanding the genetic information of plants from the Qinghai-Tibet Plateau. TPSs, CYPs, UGTs and BAHDs further contribute to a better understanding of the biology and complexity of PMGs in P. veitchii. Our study will help reveal the mechanisms underlying the biosynthesis pathway of these specific monoterpene glycosides and aid in the comprehensive utilization of this multifunctional plant.

Metabolome and transcriptome associated analysis of sesquiterpenoid metabolism in Nardostachys jatamansi.

Background: Nardostachys jatamansi, an extremely endangered valuable plant of the alpine Himalayas, can synthesize specific sesquiterpenoids with multiple effective therapies and is widely exploited for the preparation of drugs, cosmetics and even religious functions (e.g., well-known spikenard). However, how accumulation trend of the sesquiterpenoids in tissues and the molecular mechanisms underlying the production of the active ingredients are not well understood. Methods: The single-molecule real-time (SMRT) and RNA-seq transcriptome sequencing were combined to analyse the roots, rhizomes, leaves, flowers and anthocaulus of N. jatamansi. The phytochemical analysis was performed by gas chromatography‒mass spectrometry (GC‒MS) and ultrahigh-performance liquid chromatography (UPLC). Results: A high-quality full-length reference transcriptome with 26,503 unigenes was generated for the first time. For volatile components, a total of sixty-five compounds were successfully identified, including fifty sesquiterpenoids. Their accumulation levels in five tissues were significantly varied, and most of the sesquiterpenoids were mainly enriched in roots and rhizomes. In addition, five aromatic compounds were only detected in flowers, which may help the plant attract insects for pollination. For nonvolatile ingredients, nardosinone-type sesquiterpenoids (nardosinone, kanshone C, and isonardosinone) were detected almost exclusively in roots and rhizomes. The candidate genes associated with sesquiterpenoid biosynthesis were identified by transcriptome analysis. Consistently, it was found that most biosynthesis genes were abundantly expressed in the roots and rhizomes according to the functional enrichment and expression patterns results. There was a positive correlation between the expression profile of genes related to the biosynthesis and the accumulation level of sesquiterpenoids in tissues. Gene family function analysis identified 28 NjTPSs and 43 NjCYPs that may be involved in the biosynthesis of the corresponding sesquiterpenoids. Furthermore, gene family functional analysis and gene coexpression network analysis revealed 28 NjTPSs and 43 NjCYPs associated with nardosinone-type sesquiterpenoid biosynthesis. Conclusion: Our research results reveal the framework of sesquiterpenoids accumulation and biosynthesis in plant tissues and provide valuable support for further studies to elucidate the molecular mechanisms of sesquiterpenoid regulation and accumulation in N. jatamansi and will also contribute to the comprehensive utilization of this alpine plant.