Magnesium Hydride Enhances Both Growth and Bioactive Compound Biosynthesis in Salvia miltiorrhiza: A Novel Eco-Friendly Approach for Medicinal Plant Cultivation

Medicinal plants have garnered widespread attention owing to their broad range of biological activities and pharmaceutical value. However, achieving a balance between promoting plant growth and enhancing bioactive compound accumulation remains a major challenge in current research. In this study, Salvia miltiorrhiza was selected as the model organism to investigate the effects of MgH2 on growth and the accumulation of bioactive compounds. Our results demonstrated that MgH2 treatment at 10.0 mg kg−1 soil increased the seed germination rate by 49.3%. At the optimal concentration of 12.5 mg kg−1 soil, MgH2 significantly promoted seedling growth, enhancing root biomass by 745.6% after 4 weeks of treatment. Furthermore, MgH2 application dramatically boosted the accumulation of bioactive compounds, increasing the total content of rosmarinic acid and dihydrotanshinone by 1271.8% and 2407.7%, respectively. Transcriptome analysis revealed that these improvements were associated with the upregulation of genes involved in plant hormone signal transduction, energy metabolism, and the biosynthesis pathways of tanshinones and salvianolic acids. Our findings provide the first evidence that MgH2 acts as a dual-functional regulator, simultaneously enhancing both plant growth and secondary metabolite accumulation in medicinal plants, offering a green and efficient cultivation strategy for the sustainable production of high-quality S. miltiorrhiza.