Enhancing biosynthesis and bioactivity of Trachyspermum ammi seed essential oil in response to drought and Azotobacter chroococcum stimulation

Abstract

BackgroundPlant growth-promoting bacteria have fundamental role in enhancing natural bioactive compounds and proved to increase the plant growth and mineral availability in soil. These phytochemicals, like phenolic and essential oils, illustrated wide range of biological properties. This study was designed to evaluate the effect of Azotobacter chroococcum (A. chroococcum) alone or in combination with slight (irrigation at 80% filed capacity) or moderate (irrigation at 60% filed capacity) drought stresses on the yield, phytochemicals, antioxidant, and the toxicity of Trachyspermum ammi (T. ammi) seeds essential oil.ResultsOverall, the application of A. chroococcum as plant growth-promoting agent together with slight drought stress significantly (p < 0.05) resulted in higher essential oil yield, total phenolic, total flavonoid, and higher antioxidant activity. The gene expression analysis in the developing seeds confirmed the up-regulation in the expression of antioxidant-related gene (SOD) and thymol synthesis gene (TSG) upon A. chroococcum bacteria treatment in combination with slight drought stress. The toxicity study showed no prominent signs of toxicity in mice upon oral administration of essential oil up to 100 mg/kg body weight for 28 days.ConclusionThe slight drought stress (irrigation at 80% filed capacity) together with treatment of T. ammi plant with A. chroococcum bacteria as plant growth-promoting agent could be promising approach in improving the yield and medicinal value of the T. ammi seeds essential oil.Graphical