Changes in physiological, phytochemical traits and gene expression of two Perovskia species in response to water deficit

Perovskia species are considered as valuable ornamental plants. In the present study, the enzymatic and nonenzymatic antioxidants were evaluated in P. atriplicifolia, and P. abrotanoides in response to water deficit stress. The root harvesting was performed after 0, 3, 5, 7, and 9 days exposure to stress. In both species, total phenolics content, total flavonoids, enzymatic antioxidant activities, total tanshinones, tanshinone IIA, cryptotanshinone, hydroxy-cryptotanshinone, and proline substantially increased with the severity of stress. In the current study, the variations in tanshinone profile and the expression of genes (DXS1, HMGR, KSL) related to tanshinones biosynthesis were also investigated. The results revealed the negative trend between the concentration of malondialdehyde, and hydrogen peroxide as well as the harmonized augmentation in activities of enzymatic antioxidants including guaiacol peroxidase, and ascorbate peroxidase, exclusively on 7th day of stress. The expression ratios of all studied genes were markedly induced by the drought stress. The content of major oxidative stress-related indicators suggested that P. atriplicifolia should be better pre-adapted to water deficit physiological tolerance than P. abrotanoides. Finally, the experimental results can provide further insight into differential responses to imposed water-limited stress along with choice of the optimal eustress treatment to obtain the desired composition of pharmacologically useful diterpenoids.