Overexpression of 3-hydroxy-3-methylglutaryl Eoenzyme-A reductase-1 (HMGR1) Enhanced andrographolide Accumulation in Andrographis paniculata (Burm.F.)

3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR) enzyme plays an important role in the biosynthesis of diterpene lactones such as andrographolide, a specialized metabolite that is widely used as a therapeutic agent.This study aimed to enhance the content of andrographolide through the overexpression of 3-hydroxy-3-methylglutaryl coenzyme-A reductase-1 (HMGR1) in A. paniculata.HMGR1 was constructed into the pBI121 expression vector controlled by the cauliflower mosaic virus (CaMV 35S) promoter.The pBI121-HMGR1 construct was transformed to A. paniculata through Agrobacteriummediated transformation followed by plant regeneration to obtain transgenic plants.Polymerase chain reaction (PCR) analysis was conducted to validate the transgenic plants, quantitative reverse transcription PCR (RT-qPCR) was used for the HMGR1 expression analysis, and high-performance liquid chromatography was employed to quantify the andrographolide content of the transgenic plants.PCR analysis on the transgenic plantlets indicated the presence of a 2,262 bp fragment that corresponded to HMGR1, thus confirming the integration of HMGR1 into the A. paniculata genome.The RT-qPCR results showed a 52.5-fold greater HMGR1 expression in the transgenic plant under the CaMV 35S promoter compared to the normal plant.As the expression level of HMGR1 increased, the amount of andrographolide was enhanced by up to 2.6 times in the transgenic plant compared to the control plant.This study demonstrates that the overexpression of HMGR1 driven by CaMV 35S can enhance the production of andrographolide in A. paniculata.