The effects of water deficit on the expression of monoterpene synthases and essential oils composition in Salvia ecotypes.

The medicinal sage plant (Salvia spp.), belonging to Lamiaceae family, is one of the most important medicinal and aromatic plants. The members of this genus are globally known due to its antimicrobial, antioxidant, astringent, spasmolytic, antihidrotic and specific sensorial properties. In this study, we investigated the potential impact of water deficit on transcript abundance, and essential oil composition of five major metabolites, i.e. 1-8 cineole, α-β-thujone, camphor, and borneol in three genotypes of Salvia spp. Results showed that relative expression of three genes and their corresponding metabolites increased together at three stages under drought condition, but the CS gene transcript decreased independently from 1,8-cineole in garden sage. Furthermore, borneol changed differently compared to the BS gene expression in control and drought treatment plants of S. reuterana (Yasuj). The competitive synthesis of ß-thujone, and α-thujone by SS gene were demonstrated in S. officinalis and Yasuj ecotype of S. reuterana; whereas, no change was observed for Urmia ecotype of S. reuterana. There was no precursor shortage to synthesis of borneol and camphor in garden sage; however increasing the BS led to high production of borneol and low camphor in S. reuterana under drought stress. As a mechanism, secondary metabolites enable the plants to cope with unfavorable conditions, but genetic differences might affect the quantity and quality of these compounds. © Prof. H.S. Srivastava Foundation for Science and Society 2020.