Blue light regulates terpenoid biosynthesis via jasmonic acid signaling in the medicinal plant Andrographis paniculata

The medicinal plant Andrographis paniculata has garnered attention for its remarkable effectiveness in treating inflammation, which is attributed to its active terpenoid compounds. However, the regulatory mechanisms governing their biosynthesis remain unknown. In this study, we showed that exposing Andrographis paniculata plants to blue light increases the contents of the main active components, andrographolide and 14-deoxyandrographolide, and promotes the expression of key genes encoding enzymes in the diterpene lactone biosynthetic pathway, including ent-copalyl diphosphate synthase (ApCPS2), geranyl(geranyl)diphosphate synthase 1 (ApGGPPS1), and ApGGPPS2. Combined transcriptomic and metabolomic analysis revealed that blue light regulates the light and jasmonic acid (JA) signaling pathways. Furthermore, we demonstrated that the transcription factor ApHY5 directly binds to the promoters of ApCPS2, ApGGPPS1, and ApGGPPS2, thereby activating transcription. In addition, ApHY5 interacted with the transcription factor ApMYC2 to enhance its function, thereby promoting the accumulation of diterpene lactones. Silencing of ApHY5 or ApMYC2 resulted in lower expression levels of genes involved in diterpene lactone biosynthesis and reduced accumulation of these components, while overexpression of either gene had the opposite effect. This study elucidates a mechanism for blue light-regulated terpenoid metabolism that involves the JA signaling pathway, offering strategies to enhance the biosynthesis of effective components in medicinal plants.