Dataset Information

Accumulation of astragalosides and related gene expression in different organs of Astragalus membranaceus Bge. var mongholicus (Bge.).

ABSTRACT: Astragalus membranaceus is one of the most important traditional Korean and Chinese medicinal herbs because it contains triterpenoid saponins (astragaloside I, II, III, and IV), which have beneficial and pharmacological effects on health. In this study, we analyzed 10 mevalonate pathway genes that are involved in astragaloside biosynthesis using the Illumina/Solexa HiSeq2000 platform. We determined the expression levels of the 10 genes using quantitative real-time PCR, and analyzed the accumulation of astragalosides in different organs using high-performance liquid chromatography. Genes related to the mevalonate pathway were expressed in different levels in different organs. Almost all genes showed high transcript levels in the stem and leaf, with the lowest transcript levels being recorded in the root. In contrast, most astragalosides accumulated in the root. In particular, the astragaloside IV content was distributed in the following order: root (0.58 mg/g DW) > flower (0.27 mg/g DW) > stem (0.23 mg/g DW) > leaf (0.04 mg/g DW). In the root, astragaloside II exhibited the highest content (2.09 mg/g DW) compared to astragaloside I, III, and IV. Notably, gene expression did not follow the same pattern as astragaloside accumulation. We suggest carefully that astragalosides are synthesized in the leaves and stem and then translocated to the root. This study contributes towards improving our understanding of astragaloside biosynthesis in A. membranaceus.

SUBMITTER: Kim YB

PROVIDER: S-EPMC6270750 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Accumulation of astragalosides and related gene expression in different organs of Astragalus membranaceus Bge. var mongholicus (Bge.).

Kim Yeon Bok YB Thwe Aye Aye AA Li Xiaohua X Tuan Pham Anh PA Lee Sanghyun S Lee Jong Won JW Arasu Mariadhas Valan MV Al-Dhabi Naif Abdullah NA Park Sang Un SU

Molecules (Basel, Switzerland) 20140725 8

Astragalus membranaceus is one of the most important traditional Korean and Chinese medicinal herbs because it contains triterpenoid saponins (astragaloside I, II, III, and IV), which have beneficial and pharmacological effects on health. In this study, we analyzed 10 mevalonate pathway genes that are involved in astragaloside biosynthesis using the Illumina/Solexa HiSeq2000 platform. We determined the expression levels of the 10 genes using quantitative real-time PCR, and analyzed the accumulat ...[more]

PMID: 25068786

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Project description:Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao (A. mongolicus, family Leguminosae) is one of the most important traditional Chinese herbs. Among many secondary metabolites it produces, the effective bioactive constituents include isoflavonoids and triterpene saponins. The genomic resources regarding the biosynthesis of these metabolites in A. mongolicus are limited. Although roots are the primary material harvested for medical use, the biosynthesis of the bioactive compounds and its regulation in A. mongolicus are not well understood. Therefore, a global transcriptome analysis on A. mongolicus tissues was performed to identify the genes essential for the metabolism and to profile their expression patterns in greater details.RNA-sequencing was performed for three different A. mongolicus tissues: leaf, stem, and root, using the Illumina Hiseq2000 platform. A total of 159.5 million raw sequence reads were generated, and assembled into 186,324 unigenes with an N50 of 1,524bp. Among them, 129,966 unigenes (~69.7%) were annotated using four public databases (Swiss-Prot, TrEMBL, CDD, Pfam), and 90,202, 63,946, and 78,326 unigenes were found to express in leaves, roots, and stems, respectively. A total of 8,025 transcription factors (TFs) were identified, in which the four largest families, bHLH, MYB, C3H, and WRKY, were implicated in regulation of tissue development, metabolisms, stress response, etc. Unigenes associated with secondary metabolism, especially those with isolavonoids and triterpene saponins biosynthesis were characterized and profiled. Most genes involved in the isoflavonoids biosynthesis had the lowest expression in the leaves, and the highest in the stems. For triterpene saponin biosynthesis, we found the genes in MVA and non-MVA pathways were differentially expressed among three examined tissues, indicating the parallel but compartmentally separated biosynthesis pathways of IPP and DMAPP in A. mongolicus. The first committed enzyme in triterpene saponin biosynthesis from A. mongolicus, cycloartenol synthase (AmCAS), which belongs to the oxidosqualene cyclase family, was cloned by us to study the astragalosides biosynthesis. Further co-expression analysis indicated the candidate CYP450s and glycosyltransferases (GTs) in the cascade of triterpene saponins biosynthesis. The presence of the large CYP450 families in A. mongolicus was further compared with those from Medicago truncatula and Arabidopsis thaliana, and the diversity and phylegenetic relationships of the CYP450 families were established.A transcriptome study was performed for A. mongolicus tissues to construct and profile their metabolic pathways, especially for the important bioactive molecules. The results revealed a comprehensive profile for metabolic activities among tissues, pointing to the equal importance of leaf, stem, and root in A. mongolicus for the production of bioactive compounds. This work provides valuable resources for bioengineering and in vitro synthesis of the natural compounds for medical research and for potential drug development.

Project description:Radix Astragali is commonly used in traditional Chinese medicine, and its quality is closely related to ecological factors, such as climate and soil, in the production area. To provide high-quality Radix Astragali to Chinese and foreign markets, we used maximum entropy model and statistical analysis method, combined with data on ecological factors, Astragalus membranaceus var. mongholicus geographical distribution, and index component content to predict the ecological suitability distribution of A. membranaceus var. mongholicus and establish the relationship between astragaloside IV and calycosin-7-glucoside in this species and ecological factors. Subsequently, we could determine the suitability regionalization of high-quality A. membranaceus var. mongholicus in Inner Mongolia, China. The results showed that the standard deviation of seasonal changes in temperature (40.6%), precipitation in October (15.7%), vegetation type (14.3%), soil type (9.2%), and mean sunshine duration in the growing season (9.1%) were the top five most influential factors out of the 17 main ecological factors affecting the distribution of A. membranaceus var. mongholicus. The standard deviation of seasonal changes in temperature, precipitation in October, precipitation in April, soil pH, and mean sunshine duration in the growing season were found to be the key ecological factors affecting the accumulation of astragaloside IV and calycosin-7-glucoside in A. membranaceus var. mongholicus. The regions with the highest-quality A. membranaceus var. mongholicus were distributed in Baotou (Guyang County), Hohhot (Wuchuan County), and central Wulanchabu (Chahar Right Middle Banner, Chahar Right Back Banner, and Shangdu County) and its surroundings in Inner Mongolia. Baotou, Hohhot, and their surrounding areas were the main traditional production areas of A. membranaceus var. mongholicus, and central Wulanchabu was a potentially suitable distribution area of this species. The main production areas were consistent with the actual production base of A. membranaceus var. mongholicus. This study therefore provides a scientific basis to guide the cultivation of A. membranaceus var. mongholicus.

Project description:BACKGROUND:Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao is one of the most common herbs widely used in South and East Asia, to enhance people's health and reinforce vital energy. Despite its prevalence, however, the knowledge about phytochemical compositions and metabolite biosynthesis in Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao is very limited. RESULTS:An integrated metabolomics and transcriptomics analysis using state-of-the-art UPLC-Q-Orbitrap mass spectrometer and advanced bioinformatics pipeline were conducted to study global metabolic profiles and phytochemical ingredients/biosynthesis in Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao. A total of 5435 metabolites were detected, from which 2190 were annotated, representing an order of magnitude increase over previously known. Metabolic profiling of Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao tissues found contents and synthetic enzymes for phytochemicals were significantly higher in leaf and stem in general, whereas the contents of the main bioactive ingredients were significantly enriched in root, underlying the value of root in herbal remedies. Using integrated metabolomics and transcriptomics data, we illustrated the complete pathways of phenylpropanoid biosynthesis, flavonoid biosynthesis, and isoflavonoid biosynthesis, in which some were first reported in the herb. More importantly, we discovered novel flavonoid derivatives using informatics method for neutral loss scan, in addition to inferring their likely synthesis pathways in Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao. CONCLUSIONS:The current study represents the most comprehensive metabolomics and transcriptomics analysis on traditional herb Astragalus membranaceus Bge. var. mongolicus (Bge.) Hsiao. We demonstrated our integrated metabolomics and transcriptomics approach offers great potentials in discovering novel metabolite structure and associated synthesis pathways. This study provides novel insights into the phytochemical ingredients, metabolite biosynthesis, and complex metabolic network in herbs, highlighting the rich natural resource and nutritional value of traditional herbal plants.

Dataset Information

Accumulation of astragalosides and related gene expression in different organs of Astragalus membranaceus Bge. var mongholicus (Bge.).

Publications

Accumulation of astragalosides and related gene expression in different organs of Astragalus membranaceus Bge. var mongholicus (Bge.).

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