Comprehensive metabolic and transcriptomic profiling of various tissues provide insights for saponin biosynthesis in the medicinally important Asparagus racemosus

Prabhakar Lal Srivastava,Raviraj M Kalunke,Anurag Shukla

doi:10.1038/s41598-018-27440-y

Prabhakar Lal Srivastava, Raviraj M Kalunke + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-27440-y

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Abstract

Asparagus racemosus (Shatavari), belongs to the family Asparagaceae and is known as a “curer of hundred diseases” since ancient time. This plant has been exploited as a food supplement to enhance immune system and regarded as a highly valued medicinal plant in Ayurvedic medicine system for the treatment of various ailments such as gastric ulcers, dyspepsia, cardiovascular diseases, neurodegenerative diseases, cancer, as a galactogogue and against several other diseases. In depth metabolic fingerprinting of various parts of the plant led to the identification of 13 monoterpenoids exclusively present in roots. LC-MS profiling led to the identification of a significant number of steroidal saponins (33). However, we have also identified 16 triterpene saponins for the first time in A. racemosus. In order to understand the molecular basis of biosynthesis of major components, transcriptome sequencing from three different tissues (root, leaf and fruit) was carried out. Functional annotation of A. racemosus transcriptome resulted in the identification of 153 transcripts involved in steroidal saponin biosynthesis, 45 transcripts in triterpene saponin biosynthesis, 44 transcripts in monoterpenoid biosynthesis and 79 transcripts in flavonoid biosynthesis. These findings will pave the way for better understanding of the molecular basis of steroidal saponin, triterpene saponin, monoterpenoids and flavonoid biosynthesis in A. racemosus.

Highlights

Asparagus racemosus is one of the most valuable medicinal plants, regarded as a “Queen of herbs” in Ayurvedic health system and has been used worldwide to cure various diseases1
The metabolic fingerprinting of three different tissues of A. racemosus using GC-MS and LC-MS have led to the identification of a large number of monoterpenoids, steroidal/triterpene saponins and flavonoids which have not been reported earlier
Our findings clearly indicated that where monoterpenoids are exclusively present in the root, steroidal saponins are dominated in leaf and root tissues, whereas triterpene saponins and flavonoids are dominated in leaf and fruit tissues

Summary

Introduction

Asparagus racemosus is one of the most valuable medicinal plants, regarded as a “Queen of herbs” in Ayurvedic health system and has been used worldwide to cure various diseases. Flowers and fruits of A. racemosus are known to contain flavonoids such as quercetin and its glycosides, rutin (quercetin 3-O-rutinoside) and hyperoside (quercetin 3-O-galactoside), whereas quercetin 3-glucuronide, ferulic, caffeic and chlorogenic acids have been isolated from the leaf extracts3,4 The supply of these natural products suffers www.nature.com/scientificreports/. Due to diversified therapeutic applications of A. racemosus, it is of great interest to perform the comprehensive metabolic and transcriptome profiling to have better insight about metabolic content and the molecular basis of their biosynthesis In this manuscript, we present the metabolic fingerprinting and transcriptome sequencing of three different tissues (root, leaf and fruit) of A. racemosus to understand the molecular basis for the biosynthesis of steroidal saponins, triterpene saponins, monoterpenoids and flavonoids. Understanding the biosynthetic pathway of shatavarins will pave the way for large-scale production of these highly valued compounds using metabolic engineering tools

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