Phenotypic Traits, Hormonal Distribution, and Metabolite Profiling of Isatis indigotica Seeds from 21 Samples in China: A Traditional Chinese Medicinal Herb

"Banlangen" (<i>Isatis indigotica</i> Fort., indigowoad root) is the dried root of a plant in the Cruciferae (Brassicaceae) family, which has been cultivated in China for over 2000 years. This herb has significant medicinal value and played an important therapeutic role during the COVID-19 pandemic. <i>Isatis indigotica</i> is widely cultivated in China, with varying seed quality across different regions. Investigating the seed quality and distribution of endogenous metabolites of <i>Isatis indigotica</i> from various regions is of great significance for its efficient utilization. In this study, 21 samples from <i>Isatis indigotica</i> seeds were collected from 15 different regions of China and analyzed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). A systematic analysis was conducted on seed phenotypes, germination rate, endogenous metabolites, and hormones. The results showed that the germplasm traits of <i>Isatis indigotica</i> from northern China were generally superior to those from southern China, with seed size positively correlated with the accumulation of sugars (D-allose, D-(+)-cellobiose, maltitol, α-D-glucopyranoside, d-galactose, maltose, D-(-)-fructose, and galactitol) and organic acids (hexadecanoic acid, benzoic acid, propanedioic acid, butanedioic acid, and cinnamic acid). Additionally, seed germination in the samples from SuQian and Shanxi was closely related to hormone distribution (gibberellic acid and abscisic acid). This study provides valuable data to support the evaluation of seeds from different sources of medicinal plants and has important implications for the cultivation and identification of <i>Isatis indigotica</i> varieties.