Effects of Genetic Transformation on the Antioxidant Activity of “Hairy” Roots of Althaea officinalis L., Artemisia vulgaris L., and Artemisia tilesii Ledeb

Agrobacterium rhizogenes -mediated genetic transformation is a well-known method for the induction of “hairy” root cultures of different plant species that allows to incorporate the bacterial rol genes into the plant genome. Introduction of the rol genes known as the stimulators of plant secondary metabolism, as well as a contact with phytopathogenic bacteria, may affect different growth parameters, such as weight increase, accumulation of secondary metabolites, and activity of enzymes, etc. after a long-term cultivation study of changes induced by Agrobacterium -mediated transformation and a transfer of foreign genes into the plant genome is of special interest. The activity of the enzymes (catalase and superoxide dismutase) belonging to the plant antioxidant defense system, as well as the total flavonoid content, the antioxidant and reducing activity of extracts from “hairy” root cultures, including Althaea officinalis , Artemisia vulgaris , and Artemisia tilesii , which were earlier obtained through the A. rhizogenes-mediated transformation (A4 strain with the human interferon ifn-α2b gene) were compared. PCR analysis confirmed the presence of the transferred genes in the corresponding “hairy” roots after long-term cultivation. A significant variability has been observed in the catalase and superoxide dismutase (SOD) activities among different “hairy” root lines. In particular, some lines characterized by increased activity of both enzymes have been identified. Catalase and SOD activities increased, respectively, 4.4 times and twice compared with the activity of extracts from the roots of the control plants. The possibility of significant increases in the total flavonoid content (by 4.6 times) and the levels of antioxidant and reducing activities in some samples of transgenic roots have been shown. The maximum flavonoid contents reached in the “hairy” roots of A. officinalis , A. vulgaris , and A. tilesii 4.60 ± 0.19, 4.55 ± 0.36, and 9.21 ± 1.28 mg/g of fresh weight. Thus, it has been demonstrated that genetic transformation induces changes in both the synthesis of metabolites with antioxidant properties and the activities of the antioxidant defense system enzymes. Changes were retained during 5–8 years after the induction of “hairy” roots. These results confirm a prolonged effect of genetic transformation on the functions of cells in the medicinal plant species, including marshmallow and two wormwood species. The established effect of increasing the f