Integrated Analysis of Transcriptome and Metabolome Profiles in Astragslus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao Seedlings Under Drought Stress

TL;DR

This study explores how Astragalus membranaceus seedlings respond to drought stress by analyzing gene and metabolite changes in different tissues.

Contribution

The study reveals a tissue-specific 'shoot–root partitioned coordination' mechanism in Astragalus under drought stress.

Findings

Drought stress caused 2987 differentially expressed genes and 921 differentially accumulated metabolites.

Aboveground tissues activated antioxidant defenses, while roots reconfigured amino acid metabolism.

Stress intensity influenced gene and metabolite responses, showing an 'active coping' strategy.

Abstract

Background: Astragalus membranaceus is a traditional Chinese medicinal herb with significant pharmacological value. Drought stress adversely affects its biomass accumulation and medicinal quality. Methods: In this study, we performed physiological profiling, transcriptomics, and metabolomics analyses on A. membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao seedlings to elucidate the response mechanisms in both aboveground and root tissues under varying drought stress intensities (Control, CK; Light Drought LD; Moderate Drought MD; Severe Drought SD). Results: Our findings indicate that LD primarily activated antioxidant enzymes, whereas severe stress led to the dominance of osmotic adjustment. Compared with CK, drought treatments resulted in 2987 differentially expressed genes (DEGs; 1674 up-regulated and 1313 down-regulated) and 921 differentially accumulated metabolites (DAMs)—562 in positive ionization mode (224 up, 338 down) and 359 in negative ionization mode (166 up, 193 down). Both gene expression and metabolite accumulation exhibited pronounced stress intensity-dependent patterns, suggesting that A. mongholicus initiates a broad, gene activation-led “active coping” strategy and mobilizes increasingly extensive metabolic pathways as drought intensifies. Conclusions: Integrated transcriptomic and metabolomic analyses revealed a tissue-specific “shoot–root partitioned coordination” mechanism: aboveground tissues activated a glutathione metabolism-centered “antioxidant–osmotic adjustment” defense, while root tissues reconfigured amino acid metabolism to maintain energy supply and signaling. This synergistic coordination represents a core adaptive strategy of A. mongholicus under drought conditions. Our study provides deeper insights into the drought resistance mechanisms of Astragalus and offers valuable references for breeding drought-tolerant varieties of Astragalus and other medicinal plants.

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