Xibei zhiwu xuebao (Jun 2024)
Metabolic mechanism of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao in response to repeated drought stress
Abstract
Abstract [Objective] Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao is an important primitive plant of astragali radix, and its main planting areas are arid and semi-arid areas in Inner Mongolia, Shanxi, Gansu, and other places. Irregular intermittent rainfalls cause drought and rehydration cycle in plants. Studying the characteristics of metabolites in A . membranaceus var. mongholicus during drought and rehydration is crucial to understand the drought tolerance mechanism in response to natural intermittent rainfalls. [Methods] The seedlings of annual A . membranaceus var. mongholicus were used as materials. After repeated drought and rehydration treatment, soil nutrients and root growth in potted plants were measured. The primary metabolites of A . membranaceus var. mongholicus were analyzed using NMR based technology. Differential metabolite screening and metabolic pathway were analyzed. Total flavonoids, total saponins, and polysaccharides in the roots of A . membranaceus var. mongholicus were determined. [Results] (1) A . membranaceus var. mongholicus showed a trend of decreasing in root diameter and increasing in root length and fibrous root density under drought stress. (2) Under drought and rehydration treatment, a total of 42 metabolites were detected, containing mainly amino acids and their derivatives, organic acids, amines, ammonia compounds, and sugars. Metabolic pathway analysis showed that amino acid metabolism pathways were mainly affected during repeated drought stress. Plant drought resistance was enhanced by increasing the content of aspartate, alanine, glutamate, proline, and arginine, as well as reducing the content of asparagine, tryptophan, and 4-aminobutyrate. Specifically, the increase in metabolites such as alanine, glutamate, and proline was 1-3 times, while metabolites such as tryptophan and 4-aminobutyric acid were decreased by 1-2 times. (3) Under the first round of drought stress, the accumulation of astragaloside was decreased; after the second round of drought stress, the production of three active substances, namely astragaloside, total flavonoids, and polysaccharides, showed a downward trend. [Conclusion] Amino acids and their derivatives are closely related in response to drought stress in A . membranaceus var. mongholicus. Plant regulates its secondary metabolites in response to environmental changes
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