Methyl jasmonate mitigates biochemical and phytochemical changes in salt stressed Stevia rebaudiana plants

This study explored the effects of salt stress on growth, oxidative stress, and steviol glycoside content in Stevia rebaudiana Bertoni plants cultivated in soil supplemented with methyl jasmonate (MeJA). Stevia plants were cultivated under normal and salt stress conditions, with and without MeJA supplements of 30 ?M, 60 ?M, and 120 ?M. Samples were harvested after the 1st, 3rd, 5th, 10th, and 15th day of treatment. The levels of chlorophyll (p<0.0001), carotenoids (p<0.0001), and antioxidant enzymes such as catalase (p<0.0001), superoxide dismutase (p<0.0001), APX (p<0.0001), and glutathione reductase (p<0.0001) were observed. The quantification of steviol glycosides, including stevioside (p<0.0001) and rebaudioside-A (p<0.0001), was studied by the most advanced hyphenated technique, LC-MS/MS. The study revealed that the oxidative stress responses were significantly improved in MeJA-treated plants compared to salt-stress control plants. The level of production of phenols (p<0.0001), flavonoids, total sugar, reducing sugar, and steviol glucosides was significantly altered in salt-stress plants. MeJA showed a dose- and time-dependent significant effect on the improvement of these factors over salt stress. In conclusion, MeJA not only improves the growth of plants but also reduces oxidative stress and enhances the level of phytochemicals under saline stress.