Selenium enrichment and quality improvement of Origanum vulgare plants grown under in vitro condition with salicylic acid

One of the important sources of human selenium intake is vegetables, so increasing of selenium in edible parts of plants, biofortification, provides an effective approach to reduce selenium deficiency. Origanum vulgare L. is an important medicinal plant which is also used as a valuable spice. The present study was done to evaluate the ability of selenium accumulation of micropropagated O. vulgare under sodium selenate and/or salicylic acid treatment. Micropropagation of O. vulgare was done from shoot-tips as explants on modified Murashige & Skoog (MS) medium. After 1 month, rooted plantlets were transferred to modified Murashige & Skoog solidified medium containing sodium selenate (0, 25 and 50 mu M) and/or salicylic acid (0 and 100 mgL(-1)). After 4 wk, growth, selenium accumulation, biochemical parameters and oxidative stress indicators were determined. The results showed that the plantlets were able to accumulate 16.1 mu g g(-1) DW and 28.27 mu g g(-1) DW selenium in shoots at 25 and 50 mu M selenate sodium concentrations respectively. Both concentrations of selenium increased shoot dry weight, length of shoot and root, soluble sugars and total protein content, peroxidase and superoxide dismutase activity. On the contrary, malondialdehyde content decreased under selenium treatment. It was found that by increasing selenium concentration the content of total protein, H2O2 and antioxidant enzymes activity increased significantly. Application of salicylic acid in combination with selenium improved growth but did not affect on selenium accumulation. The obtained results can be considered as the first report of biofortification of O. vulgare under tissue culture technique.