A novel beta-glucosidase gene from Angelica dahurica and insights into the metabolic pathway of scopoletin

Angelica dahurica is a traditional Chinese medicinal product with anti-inflammatory and analgesic effects, which has received substantial attention from researchers in recent years. Scopoletin, which is an important factor involved in plant defense, and other coumarin compounds are the main active ingredients in A. dahurica. β-glucosidases (BGLUs), which hydrolyze the β-D-glycosidic bond, are involved in physiological processes such as plant growth, development, and defense. However, the functional role of BGLUs in A. dahurica remains unclear. In this study, three BGLUs were isolated and purified from A. dahurica (AdBGLUs) through transcriptomic analysis. AdBGLU1 was found to catalyze the generation of scopoletin from scopolin in vitro. It belongs to the GH1 subfamily of BGLUs that contains 547 amino acid residues and possesses the motifs required to catalyze the hydrolysis of the glycosidic bond. Substrate promiscuity testing showed that AdBGLU1 could convert skimmin, isoscopolin and tectoridin to umbelliferone, isoscopletin and tectorigenin, respectively. Molecular docking of AdBGLU1 with scopolin, skimmin, and tectoridin revealed key amino acid residues involved in their binding, such as GLN33, GLU183, and GLU453. Agrobacterium-mediated transient transformation system and RT-qPCR analysis showed that AdBGLU1 played a crucial role in the synthesis of scopoletin. This study focused on the BGLUs of A. dahurica and found its novel role in the biosynthesis of scopoletin. In addition, we speculated the mechanism through which scopoletin contributes to defense processes in A. dahurica. Altogether, the findings of this study provide valuable insights into the role of AdBGLU1 in the biosynthesis of scopoletin and its regulatory mechanisms.