Regulation of methyl jasmonate on secondary metabolism of Glycyrrhiza uralensis root

To investigate the regulation mechanism of methyl jasmonate（ MeJA） on secondary metabolism of Glycyrrhiza uralensis root，the G. uralensis seedlings were treated by 20，50，100 μmol/L MeJA. After 9 d， the contents of active ingredients in G. uralensis roots were detected by high performance liquid chromatography （HPLC）. And the expression patterns of key enzymes on biosynthetic pathway in G. uralensis roots treated by MeJA for 0，2，6，12，24，36，72 h were analyzed by real-time PCR. The results showed that the contents of glycyrrhizic acid in G. uralensis roots improved in both middle and low concentrations of MeJA，whereas the contents of liquiritin reduced in high concentrations of MeJA. The expression of GubAS，GubAO in G. uralensis roots were promoted by 20 and 50 μmol/L MeJA，and the expression of GuDOCS was promoted by 20 μmol/L MeJA. However，100 μmol/L.MeJA suppressed GubAS and GuDOCS expression. All three genes expression reached the highest level at 6 h under the induction of 20 μmol/L MeJA. It can be concluded that MeJA in middle and low concentrations have the upregulation effect on biosynthesis of glycyrrhizic acid. However only low concentration can promote the biosynthesis of liquiritin.