An experiment was conducted at the research greenhouse of Islamic Azad University, Arak branch to examine the morphological and metabolic alterations, as well as the expression of specific genes involved in the production of secondary metabolites in Salvia mirzayanii under conditions of drought, nano cerium oxide, and re-irrigation (Re-watering). The study was executed in a factorial arrangement utilizing a randomized block design with three replications. The study's findings indicate that under conditions of drought stress, there was an increase in proline levels, as well as in the activity of the antioxidant defense system, specifically the antioxidant activity of peroxidase, catalase, and superoxide dismutase enzymes. Additionally, there was an increase in the expression of genes 1-8 cineole synthase and linalool synthase. Conversely, the study observed a decrease in the number of pigments related to photosynthesis, such as chlorophyll a and b, as well as a decrease in the percentage of essential oil and growth indicators. The study utilized gas chromatography/mass spectrometry to analyze and identify the essential oils of Salvia mirzayanii plants. The results indicated that the highest concentration of essential oil compounds was observed during various treatments, including decane (19.53), spatuleol (35.86), dodecane (18.4), butyric acid (19.8), octane (17.55%), trimethyl (43.3%), linalool (17.8), and hexyl isovalerate (21.1%).
