Objective In order to study the relationship between the morphology of Angelica dahurica root system and the accumulation of coumarin-like components at different developmental stages under different light intensity treatments, to provide reference and basis for improving the quality of A. dahurica herbs and for efficient and reasonable cultivation and production. Methods The morphological indexes of A. dahurica root system were determined in 50% shade, natural light, and supplemental light treatment groups; High-performance liquid chromatography (HPLC) and correlation analysis were used to determine and screen the coumarin-like components that were strongly associated with the morphology of A. dahurica root system; The morphology of the root system of A. dahurica was observed by the application of exogenous coumarin, and the expression level of coumarin biosynthesis-related genes in the root system was determined based on the RT-qPCR technique. Results Root morphology indexes of A. dahurica (dry weight of primary root, number of lateral roots, diameter of primary root, root-crown ratio) were positively correlated with light intensity; the overall change of the total coumarin content in the different light intensity treatment groups showed an “S” - shaped curve. Umbelliferolide was significantly negatively correlated with primary root length, number of lateral roots, and root-crown ratio, and significantly positively correlated with primary root diameter; exogenous application of umbelliferolide significantly promoted the increase of the morphological parameters of A. dahurica root system (total surface area of the root, the length of the total root, and the number of root branches), and the content of the four complex coumarins (oxypeucedanin, imperatorin, phellopterin, and isoimperatorin), and significantly up-regulated the expression of key genes of coumarin biosynthesis pathway, including phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL) and other key genes expression. Conclusion A. dahurica root indexes and coumarin content varied in different light intensities and developmental periods. The exogenous application of umbelliferolide affected the establishment of dahurica root system and the accumulation of coumarin-like components in dahurica roots by regulating the expression of genes related to the coumarin synthesis pathway in dahurica roots.

Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f.  /  light intensity  /  root development  /  HPLC  /  coumarin accumulation  /  umbelliferone  /  RT-qPCR  /  oxypeucedanin  /  imperatorin  /  phellopterin  /  isoimperatorin