Genetic and chemical differentiation characterizes top-geoherb and non-top-geoherb areas in the TCM herb rhubarb

Xumei Wang,Tao Zhou,Xiaoqi Hou,Markus Ruhsam,Kai Fan,Xiaojie Sun,Yun Zhou,Lei Huang,Jie Song,Min Huang,Li Feng

doi:10.1038/s41598-018-27510-1

Abstract

Medicinal herbs of high quality and with significant clinical effects have been designated as top-geoherbs in traditional Chinese medicine (TCM). However, the validity of this concept using genetic markers has not been widely tested. In this study, we investigated the genetic variation within the Rheum palmatum complex (rhubarb), an important herbal remedy in TCM, using a phylogeographic (six chloroplast DNA regions, five nuclear DNA regions, and 14 nuclear microsatellite loci) and a chemical approach (anthraquinone content). Genetic and chemical data identified two distinct groups in the 38 analysed populations from the R. palmatum complex which geographically coincide with the traditional top-geoherb and non-top-geoherb areas of rhubarb. Molecular dating suggests that the two groups diverged in the Quaternary c. 2.0 million years ago, a time of repeated climate changes and uplift of the Qinghai-Tibetan Plateau. Our results show that the ancient TCM concept of top-geoherb and non-top-geoherb areas corresponds to genetically and chemically differentiated groups in rhubarb.

Highlights

Traditional Chinese Medicine (TCM) has developed over millenia in China and has exerted its influence on medical culture in Asia for more than a thousand years
The high-performance liquid chromatography (HPLC) results showed that eight anthraquinones were successfully detected in all samples except for aloe-emodin-8-O-β-D-glucopyranoside and rhein-8-O-β-D-glucopyranoside, which could not be found in any sample (Fig. 1a; Supplementary Fig. S1 and Table S1)
We investigated whether the concept of geo-herbalism in traditional Chinese medicine (TCM) is consistent with chemical and genetic differences between top-geoherbs and non-top-geoherbs using the R. palmatum complex, an important herbal remedy, as a case study

Summary

Introduction

Traditional Chinese Medicine (TCM) has developed over millenia in China and has exerted its influence on medical culture in Asia for more than a thousand years. The ancient practitioners of Chinese medicine called medicinal plants obtained from regions with allegedly superior efficacy top-geo-herbs, while the ones from other regions were known as non-top-geoherbs[1,2,3], suggesting a profound understanding of the differentiation between or within plant species. The herbal remedy “rhubarb” consists of the dried roots and rhizomes of any species of Rheum officinale Baill., R. palmatum Linn., or R. tanguticum According to Flora of China, the delimitation of these three rhubarb species is based primarily on the degree of leaf blade dissection and the shape of the lobes[22]. In TCM, rhubarb plants collected from Qinghai, Gansu, and Sichuan Provinces (in or near the QTP and the Hengduan Mountains) are classed as top-geoherbs compared to rhubarb collected further east, which are regarded to be non-topgeoherbs with inferior quality. It is likely that chemical and possibly genetic differentiation exists in the R. palmatum complex

Methods

Results

Conclusion