Comparative metabolomic analysis in roots of natural and cultivated Astragalus membranaceus in Mongolia

Abstract

Background: Astragalus membranaceus, a valuable medicinal plant, is widely used in the pharmaceutical, food, and nutritional industries due to its rich bioactive compounds. Its increasing demand has led to extensive cultivation of A. membranaceus to supplement natural resources and ensure a stable supply. However, comparing the metabolic characteristics of natural and cultivated plants is essential for understanding their quality, authenticity, and potential pharmacological differences.

Results: We conducted a comparative analysis of polysaccharide and monosaccharide composition and untargeted metabolite profiling in the roots of natural and cultivated A. membranaceus plants in Mongolia. The levels of alcohol soluble total polysaccharides and the major abundant monosaccharides were similar between natural and cultivated A. membranaceus roots. Whereas several less abundant monosaccharides showed reduced levels in the cultivated roots. Untargeted metabolomic profiling identified a total of 157 metabolites, among which 42 and 35 were differentially accumulated in natural and cultivated roots, respectively. Most metabolites showed increased levels in the cultivated roots; however, 32 metabolites were enriched in natural roots. Functional pathway enrichment revealed distinct metabolic features between the two root types. In natural roots, pathways related to stress response, biosynthesis of secondary metabolites, and energy production were enriched. In cultivated roots, the enriched metabolic pathways were linked to primary metabolism, growth, and energy production.

Conclusions: Our findings reveal distinct metabolic characteristics between natural and cultivated A. membranaceus roots, likely shaped by differences in growth environments, soil conditions, and adaptive metabolic reprogramming. These results provide a valuable reference for evaluating, authenticating, and distinguishing natural and cultivated A. membranaceus roots, and offer insights into their pharmacological potential and quality control.

Keywords: Astragalus; Cultivation; GC–MS; Metabolomics; Polysaccharide.

Fig. 1

Saccharide analysis in natural and cultivated A. membranaceus roots. (A) The contents of alcohol-soluble polysaccharides (APSs) in natural (n-Am) and cultivated (c-Am) A. membranaceus roots are normalized to that of n-Am roots as 1.0. (B) and (C) Major abundant and less abundant polysaccharides, respectively, were determined in n-Am and c-Am roots. Data are the mean of n = 3 replicates. Asterisks indicate significant changes in the compared samples (Student’s t-test; *, P < 0.05). GalA = Galacturonic acid; Ara = Arabinose; Glc = Glucose; Gal = Galactose; Rha = Rhamnose; Xyl = Xylose; Man = Mannose; GlcA = Glucuronic acid; Fuc = Fucose

Fig. 2

Untargeted metabolite profiling in root extracts of natural and cultivated A. membranaceus. (A) Principal component analysis of root metabolites of natural (n-Am) and cultivated (c-Am) A. membranaceus. (B) Venn diagram of differentially accumulated metabolites in n-Am and c-Am roots. (C) Types and numbers of metabolites identified in n-Am and c-Am roots

Fig. 3

Accumulation of sugars and sugar alcohols in natural and cultivated A. membranaceus roots. (A) Bar chart of the number of sugars and sugar alcohols between natural (n-Am) and cultivated (c-Am) roots. (B) Clustering heat map of identified sugars and sugar alcohols in n-Am and c-Am roots. Three biological replicates were included in the experiment. The color bar represents Z scores of metabolite levels. On the upper right of the metabolites, the superscript letters “n” and “c” denote those metabolites detected only in n-Am and c-Am roots, respectively. (C) Specifically enriched sugar and sugar alcohols in n-Am and c-Am roots

Fig. 4

Accumulation of organic acids in natural and cultivated A. membranaceus roots. (A) Bar chart of the number of organic acids between natural (n-Am) and cultivated (c-Am) roots. (B) Clustering heat map of organic acids in n-Am and c-Am roots. The experiment included three biological replicates. The color bar represents Z scores for acid levels. On the upper right of the organic acids, the superscript letters “n” and “c” denote those metabolites detected only in n-Am and c-Am roots, respectively. (C) Specifically enriched organic acids in n-Am and c-Am roots

Fig. 5

Accumulation of amino acids and amines in natural and cultivated A. membranaceus roots. (A) Bar chart of the number of amino acids in natural (n-Am), cultivated (c-Am), or both plant roots. (B) Clustering heat map of amino acids in n-Am and c-Am roots. The experiment included three biological replicates, and the color bar represents Z scores for levels of the amino acids and amines in the root samples. On the upper right of the amino acids, the superscript letters “n” and “c” denote those metabolites detected only in n-Am and c-Am roots, respectively. (C) Specifically enriched amino acids and amines in n-Am and c-Am roots

Fig. 6

Accumulation of lipids, esters, ethers, and phenolic acids in natural and cultivated A. membranaceus roots. (A) and (B) Accumulations of identified lipids, ethers, and phenols, respectively, in natural (n-Am) and cultivated (c-Am) roots. Three biological replicates were included in the experiment. The colors and sizes of the balloons represent metabolite levels. On the upper right of metabolites, the superscript letters “n” and “c” denote those metabolites detected only in n-Am and c-Am roots, respectively

Fig. 7

Metabolic pathway analysis in natural and cultivated A. membranaceus roots. (A) and (B) Metabolic pathway analysis plot created in natural (n-Am) and cultivated A. membranaceus (c-Am) roots using MetaboAnalyst 6.0. The pathway impact value on the x-axis was obtained from the pathway topological analysis. The –log10 of p-value on the y-axis was obtained from pathway enrichment analysis. The larger circles represent more significant pathway enrichments, and the darker colors represent the greater significance. On the upper right of metabolic pathways, the superscript letters “n” and “c” denote those metabolites detected only in n-Am and c-Am roots, respectively, and “d” denotes pathways identified that overlap and are associated which are overlapped but differentially accumulated metabolites. Functional roles associated with metabolic pathways identified in n-Am (C) and c-Am (D) roots