Multi-environment evaluations across ecological regions reveals climate and soil effects on flavonoids and flavonol glycosides contents in traditional Chinese medicinal plant Epimedium sagittatum and its geo-authenticity spatial patterns

The medicinal quality of Epimedium sagittatum is strongly influenced by its ecological environment; however, the environmental drivers and spatial variation patterns underlying the accumulation of flavonoid compounds across different habitats and plant organs remain poorly understood. In this study, E. sagittatum samples were collected from 41 geographic origin across nine provinces in China. The contents of six flavonol glycosides, total flavonol glycosides, and total flavonoids were quantified in roots, stems, and leaves. Environmental factors, including soil properties, climatic variables, and spatial factors, were integrated with phytochemical data using principal component analysis (PCA), correlation analysis, redundancy analysis (RDA), and co-kriging spatial prediction to evaluate quality differentiation and ecological suitability. Leaves and roots were identified as the primary accumulation organs for flavonoid compounds, whereas stems exhibited the lowest levels. Leaves showed preferential enrichment of most characteristic flavonol glycosides: epimedin A, epimedin B, icariin, Icariside I, and baohuoside I, while roots accumulated higher levels of epimedin C and total flavonol glycosides. The dominant environmental factors regulating flavonoid accumulation differed among organs: available phosphorus, altitude, and soil organic matter were the major drivers in roots; total potassium and annual precipitation primarily influenced stems; whereas annual precipitation, mean annual temperature, and altitude were key determinants in leaves. Spatial prediction revealed that eastern Guizhou, southwestern Hubei, northeastern Guangxi, and parts of Jiangxi possessed high potential for producing high-quality E. sagittatum resources. The accumulation of flavonoids in E. sagittatum exhibits pronounced organ specificity and ecological differentiation. The preferential enrichment of bioactive flavonoids in leaves supports the rationality of using leaves as the official medicinal part. This study provides valuable insights into ecological authentication, elite germplasm selection, sustainable cultivation zoning, and conservation strategies for E. sagittatum resources.