A new paradigm for the discrimination of Polygonatum geographical authenticity based on the coupling of stable isotope and secondary metabolites

• The stable isotope of δ 13 C, δ 15 N, δ 2 H and δ 18 O of Polygonatum from six provinces in southern China were determined. Polygonatum was proved to be a C3 plant based on the δ 13 C stable isotope data. • The unique linear regression equation of δ 2 H and δ 18 O is δ 2 H = 4.793*δ 18 O - 165.9 in dry underground rhizomes of Polygonatum from six provinces in southern China. • Based on the stable isotope data of δ 13 C, δ 15 N, δ 2 H and δ 18 O, the accuracy of the origin traceability for Polygonatum could reach 100% and the cross-validation rate was reach 100% by introducing the factor of polygona-polysaccharose. The genus Polygonatum, collectively known as Polygonatum or Solomon’s Seal, contains a number of species that have edible tuber-like stems. Technology to trace the origin of harvested plant materials is crucial. Traditional stable isotope tracing utilizes C, H, O, N and even other mineral elements for cluster analysis. This method currently has some shortcomings; if the sample size is small, the resolution will decrease. Additionally, if more stable isotope contents are measured, the costs will significantly increase. It is evident that it is necessary to enhance the accuracy of origin discrimination analysis without increasing the sample size or incurring excessive costs. (101) Our study selected five substances: δ 13 C, δ 15 N, δ 2 H, δ 18 O, and polygona-polysaccharose in Polygonatum tuber-like stem to distinguish the origin of samples from six cities in southern China. The accuracy of both the original classification and cross-validation accuracy reached 100%. The use of only four stable substances: δ 13 C, δ 15 N, δ 2 H and δ 18 O has reduced the accuracy of original classification and cross-validation to 84.4% and 75.6%. In addition, we studied the correlation between δ 13 C, δ 15 N, δ 2 H, δ 18 O, and the content of polygona-polysaccharose in Polygonatum samples. There is a linear positive correlation between δ 2 H and δ 18 O from six cities in south China. The δ 13 C, δ 15 N, δ 2 H, δ 18 O, and the content of polygona-polysaccharose and seven environmental parameters were also tested. We found a significant positive correlation between δ 18 O vs. latitude, and a significant positive correlation between δ 2 H vs. longitude and δ 2 H vs. annual evaporation. (138) Our study represents the first origin determination results of the stable isotope of Polygonatum. The accuracy and precision of origin identification using stable isotopes was enhanced by adding the content of polygona-polysaccharose even with a limited sample size. The linear relationship between the proportion of δ 2 H and δ 18 O in the tuber-like stems of Polygonatum could help us distinguish Polygonatum from other tuber foods. (63)