Overexpression of Tomato Prosystemin (LePS) Enhances Pest Resistance and the Production of Tanshinones in Salvia miltiorrhiza Bunge

Tanshinones are a group of active diterpenes with pharmacological properties that are widely used in the treatment of cardiovascular diseases. Jasmonate (JA) acts as an elicitor to enhance tanshinone biosynthesis in Salvia miltiorrhiza. However, because of high labor costs and undesirable chemical characteristics, the use of JA elicitation is still in the experimental stage. In our experiments, the overexpression of Lycopersicon esculentum (tomato) Prosystemin (LePS) in transgenic plants of S. miltiorrhiza increased their JA concentrations, significantly enhanced the production of tanshinone, and activated the expression of key genes in the tanshinone biosynthesis pathway. Meanwhile, the relative levels of metabolites related to defense such as sterols, terpenes, and phenolic acids were also increased in our OEP lines. In addition, when the larvae of cotton bollworms (Heliothis armigera) were fed with leaves from transgenic lines, their mortality rates rose by nearly 4-fold when compared to that of larvae exposed to leaves from the nontransformed wild type. Our study provides a new strategy for genetic engineering by which tanshinone production and pest resistance can be improved in S. miltiorrhiza. This is accomplished by simulating the wounding signal that increases the endogenous levels of JA.