Expression of Limonene Synthase Gene in Cumin Flowers in Response to Drought Stress

Limonene is a simple cyclic monoterpene which exists in essential oil of many plant families like Apiaceae, Pinnaceae, Routaceae and Lamiaceae. Limonene is converted to many derivatives like Cuminaldehyde and Perillaldehyde. Limonene production as the first intermediate in terpenoid biosynthetic pathway is a critical stage. Limonene synthase is a cyclase enzyme in biosynthetic pathway of some compositions of essential oil and is an important factor in volatile oil synthesis which catalyses reaction of conversion GPP precursor to limonene. Cumin (Cuminum cyminum L.) is an important aromatic plant from Apiaceae which has antioxidant, antibacterial and antifungal features. In this research drought stress effect has been examined on expression of Limonene synthase enzyme in normal and drought stress conditions. For this purpose, an Iranian ecotype, Ardakan-Yazd was planted under controlled condition in pots. Low (50% FC) and normal (FC) irrigation were applied, distinctly. Flowers were sampled from every pot. To assess Limonene synthase relative expression, RNAs were extracted from flower tissues. Synthetized cDNAs were amplified by Real-Time PCR using specific LS primers and reference gene primers. Change in water level caused physiological alteration in plants and also the amount of secondary metabolites affected. Results revealed that the relative Limonene synthase expression in low irrigated plants slightly enhanced compared to control. According to this research, direct relation between expression of Limonene synthase and drought stress in cumin is reported.