The root of Phlomis umbrosa has traditionally been used as a medicine in South Asian nations to treat colds and bone fractures, to staunch bleeding, and as an anti-inflammatory, and such use continues today. We identified 10 genes that are involved in terpenoid biosynthesis, while using the Illumina/Solexa HiSeq2000 platform. We investigated the transcript levels of the 10 genes using quantitative real-time PCR and quantified the level of terpenoid accumulation in different organs of P. umbrosa while using high-performance liquid chromatography. The transcript levels of PuHDR and PuHMGR1 were the highest among the studied genes. Sesamoside, an iridoid glycoside, appeared in higher quantity than shanzhiside methylester, umbroside (8-O-acetyl shanzhiside methyl ester), and acteoside. We speculate that PuHDR and PuHMGR1 may contribute to terpenoid biosynthesis in P. umbrosa. This study highlights the molecular mechanisms that underlie iridoid glycoside biosynthesis in P. umbrosa.
