Expression of Genes 1-deoxy-D-xylulose 5-phosphate Reductoisomerase (DXR), Sabinen Synthase (Tctps1) and α- terpineol Synthase (Tctps5) and its Relation to Thymol and Carvacrol Biosynthesis in Thymus vulgaris under Water Deficit Stress

Thymol and Carvacrol are the two important secondary metabolites from Thymus vulgaris that productions of them are controlled by genetic and environmental factors.
Evaluation of Water stress effects on expression of three important genes of thymol and carvacrol biosynthetic pathway and also physiological and phytochemical properties of Thymus vulgaris.
The present study was conducted in a randomized complete block design with 4 treatments and 3 replications in Institute of Medicinal Plants, ACECR, Karaj.
For this purpose, the treatments were selected as control (FC), 70% of FC, 40% of FC, and 20% of FC. Gene expression was studied using real-time PCR method, and HPLC was applied to essence analysis. Also physiological characteristic including chlorophyll content, relative water content, electrolyte leakage percentage and carotenoids content were analyzed.
The results revealed that water stress significantly influenced the gene expression (P≤ 0.05). The highest gene expression of DXR and Tctps5 was observed in 70% of FC, while the highest one of TvTPS1 was recorded in 40% of FC. Moreover, the maximum thymol and carvacrol was found in 70% of FC. In other hand the highest chlorophyll content and corotenoids content were obtained in 100% and 70% of FC respectively. Also there were not significant differences between treatments for relative water content and electrolyte leakage percentage.
The 70% of FC through influencing of genes in the firs and last of MEP pathway increased thymol and carvacrol production.