Overexpression of AtEDT1 promotes root elongation and affects medicinal secondary metabolite biosynthesis in roots of transgenic Salvia miltiorrhiza.

Medicinal secondary metabolites (salvianolic acids and tanshinones) are valuable natural bioactive compounds in Salvia miltiorrhiza and have widespread applications. Improvement of medicinal secondary metabolite accumulation through biotechnology is necessary and urgent to satisfy their increasing demand. Herein, it was demonstrated that the overexpression of the transcription factor Arabidopsis thaliana-enhanced drought tolerance 1 (AtEDT1) could affect medicinal secondary metabolite accumulation. In this study, we observed that the transgenic lines significantly conferred drought tolerance phenotype. Meanwhile, we found that the overexpression of AtEDT1 promoted root elongation in S. miltiorrhiza. Interestingly, we also found that the overexpression of AtEDT1 determined the accumulation of salvianolic acids, such as rosmarinic acid, lithospermic acid, salvianolic acid B, and total salvianolic acids due to the induction of the expression levels of salvianolic acid biosynthetic genes. Conversely, S. miltiorrhiza plants overexpressing the AtEDT1 transgene showed a decrease in tanshinone synthesis. Our results demonstrated that the overexpression of AtEDT1 significantly increased the accumulation of salvianolic acids in S. miltiorrhiza. Further studies are required to better elucidate the functional role of AtEDT1 in the regulation of phytochemical compound synthesis.