Accumulation of Astragalosides and Related Gene Expression in Different Organs of Astragalus Membranaceus Bge. var Mongholicus (Bge.)

• Main Authors: Yeon Bok Kim, Aye Aye Thwe, Xiaohua Li, Pham Anh Tuan, Sanghyun Lee, Jong Won Lee, Mariadhas Valan Arasu, Naif Abdullah Al-Dhabi, Sang Un Park
• Format: Article
• Language: English
• Published: MDPI AG 2014-07-01
• Series: Molecules
• Subjects: Astragalus membranaceus; astragalosides; gene expression; mevalonate pathway; triterpenoid saponin
• Online Access: http://www.mdpi.com/1420-3049/19/8/10922

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.