Study on the quality characteristics and geographical origin authentication of wild Rheum tanguticum in three authentic regions

Rhubarb, also known as pie plant, can be used for both food and medicine. The differences of quality characteristics of Rheum tanguticum in different regions are still uncharted and no method for geographical origin identification is available. Hence, 185 samples were collected from 37 sites in three provinces, the contents of nine major active ingredients and 16 elements were determined. The medicinal effect and quality of R. tanguticum in Qinghai were better, which was mainly reflected in the contents of rhein, sennoside A and gallic acid in Qinghai were higher than that in Sichuan and Gansu. Ecological factors, especially precipitation and light radiation, played an important role in producing higher contents of active ingredients in Qinghai R. tanguticum. Meanwhile, the differences of root element contents among regions were greater than that of rhizosphere soil, and root element were more conducive to the accumulation of major active ingredients. On this basis, LDA and OPLS-DA discriminant models with high prediction accuracy for R. tanguticum were established for the first time, and five elements (B, Cr, Cu, Na and Be) were selected as important markers for the geographic traceability. This study could provide references for quality control and evaluation of R. tanguticum in the future.