Relationship between expression of main MEP pathway genes and monoterpenes contents in Artemisia annua

Artemisia genus from Asteraceae family has 34 species in Iran with valuable medicinal compounds. The most important use of Artemisia has been the treatment of malaria in traditional Chinese medicine. In addition to artemisinin، it produces also other secondary metabolites such as polyphenols، terpenes، phytosterols and alkaloids. MEP (2-C-methyl-D-erythritol-4-phosphate pathway) pathway is a chloroplastic pathway by which monoterpenes are produced. It exists only in photosynthesis plants and some bacteria. In this study، monoterpene compounds produced by MEP pathway in three kinds of tissues including leaf، bud and flower were compared with the expression of three genes in the pathway (DXS، DXR، HDR). Monoterpene compounds were measured by GC/MS and genes expression was evaluated by Real-Time PCR. Six Monoterpene compounds including α-pinene، Camphene، β-Myrcene، 1،8-Cineole، Artemisia ketone and Camphor detected by GC/MS analysis on leaf، bud and flower extracts، with 60. 8، 54 and 78. 76 percent of extract، respectively. Artemisia ketone and Camphor had higher levels compared to other compounds. DXS expression in leaves was three times higher than that of buds and flowers. DXR showed the highest expression in flowers. Expression of HDR in leaves or buds was three times higher than that of flowers. Comparing the results of gene expression and GC/MS suggested that DXR plays more important role in producing monoterpene compounds and might be a candidate gene for genetic engineering.