Terpenoid metabolic profiling analysis of transgenic Artemisia annua L. by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry

Amorpha-4,11-diene synthase (ADS) is a very important enzyme which catalyzes the committed step of artemisinin biosynthesis. In this work, two lines of transgenic Artemisia annua L. which ADS was over-expressed (line A9) and suppressed (line Amsi), respectively, were utilized. And the transgenic line GUS with beta-Glucuronidase gene was regarded as the control. Their terpenoid metabolic profiling was investigated by using GC x GC-TOFMS. The metabolic profiling method established included simple extraction, two-dimension separation and multivariate analysis. Partial least squares discriminant analysis (PLS-DA) was used to classify two transgenic lines and the control line. Eleven important compounds in classification were identified. Most of them were sesquiterpenoids including monoterpenoid, diterpenoid and four bioprecursors of artemsisnin. Compared with the control, artemisinin and bioprecursors in the line A9 increased as a result of over-expressing ADS. Borneol and phytol also increased in the line A9, but (E)-beta-farnesene and germacrene D were reversely altered. The result indicated that over-expression of the ADS affected not only artemisinin biosynthesis, but also the whole metabolic network of terpenoid. Compared with the line A9, no opposite change of artemisinin and related derivatives was observed in the line Amsi, the ADS inhibition had no significant effect on artemisinin biosynthesis in the line Amsi.