Huangqi has long been valued in traditional Chinese medicine and is increasingly used in functional food and livestock-related applications. Its quality depends largely on root bioactive compounds, including flavonoids, saponins and polysaccharides, but these traits are difficult to assess early because the medicinal organ develops underground and chemical testing can be labor-intensive. Breeders therefore need simple, reliable markers that can guide selection in the field. Stem color varies widely among cultivated and wild Astragalus membranaceus var. mongholicus (AMM) accessions, yet its connection with root chemistry has not been systematically explained. Based on these challenges, the relationship between stem color, root metabolites and their molecular links warrants deeper investigation.
Researchers from Peking University and China Agricultural University report these findings published (DOI: 10.1093/hr/uhag088) on March 4, 2026 in Horticulture Research. The study examined how stem pigmentation is connected to root quality in AMM by combining field surveys, high-performance liquid chromatography with ultraviolet detection (HPLC-UV), gas chromatography-ion mobility spectrometry (GC-IMS), metabolomics, transcriptomics, weighted gene co-expression network analysis (WGCNA), functional enzyme assays and molecular modeling.
The team first surveyed two major production regions and 873 wild AMM accessions from 47 natural populations across eight provinces, confirming that stem color is a highly variable trait. Chemical tests then revealed a consistent pattern: red-stemmed roots contained higher levels of four representative isoflavones—calycosin 7-O-β-D-glucoside, calycosin, formononetin 7-O-β-D-glucoside and formononetin—than green-stemmed roots. The trend appeared in greenhouse-grown plants, plants of different ages and samples from multiple production regions. GC-IMS further showed that red-stemmed roots had higher overall volatile organic compound (VOC) abundance, including several aroma-related compounds used as quality references for Huangqi. Metabolomic analysis identified 784 metabolites and found that red stems specifically accumulated five anthocyanins, with cyanidin derivatives standing out as the main chemical basis of the red phenotype. Transcriptomic analysis showed broader activation of flavonoid and phenylpropanoid biosynthesis. WGCNA highlighted six key genes—AmC4H, AmCHS, AmCHI, AmF3H, AmF3'H and AmBZ1—associated with red stem formation. Functional assays confirmed their roles in anthocyanin biosynthesis, while molecular modeling explained how the AmBZ1 protein recognizes cyanidin and stabilizes anthocyanin products through glycosylation. Together, the results suggest that red stems signal a wider remodeling of secondary metabolism, linking aboveground pigmentation with root isoflavone accumulation.
The authors said the work turns a simple field trait into a useful biological signal. Red stem color, they said, appears to reflect coordinated changes in the flavonoid network rather than a cosmetic difference alone. This visible cue could help breeders identify promising AMM plants at earlier growth stages, when root chemical quality cannot yet be easily measured. They said the next step is to test the relationship in broader genetic backgrounds and environments, so that stem color can be used more confidently in practical Huangqi breeding and cultivation.
The study points to a practical strategy for medicinal plant improvement: using visible traits as entry points for understanding hidden chemical quality. For Huangqi cultivation, red stem color may support early germplasm screening, elite line development, quality classification and traceability. The anthocyanin-rich aerial parts of red-stemmed AMM may also have potential value in forage and functional applications, although such uses require further evaluation. More broadly, the findings offer a model for connecting plant appearance with metabolite accumulation and molecular regulation, helping translate field-level observations into tools for molecular breeding and standardized production of medicinal crops. This approach may also help producers reduce unnecessary chemical screening in early selection stages while keeping later quality verification more targeted and evidence-based.
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References
DOI
10.1093/hr/uhag088
Original Source URL
https://doi.org/10.1093/hr/uhag088
Funding information
This work was supported by National Natural Science Foundation of China (no. 81891011), National Key Research and Development Program of China (no. 2023YFA0914100), and China Postdoctoral Science Foundation (no. 2025M773890).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.