The impact of salicylic acid on some growt parameters and antioxidant enzymes of glutathione-ascorbate cycle in tomato plant under in vitro culture

Salicylic acid is a plant hormone which accumulates ROS production like H2O2 as a signal molecule and in toxic concentration cause oxidative stress with hyper accumulation of ROS. Plants use enzymatic antioxidant like glutathione-ascorbate cycle enzymes and non-enzymatic antioxidant such as ASA and DHASA against oxidative stress. The effect of salicylic acid on ascorbate –glutathione cycle antioxidants in tomato plants as amodel plant is not clear Tomato (Lycopericon esculentum Mill) plants cultured in vitro for 4 weeks on MS medium containing salicylic acid (SA) treatment in concentrations of 0.0001, 0.001, 0.01, 0.1 and 0.5 mM SA.... In this study, the effect of salicylic acid investigated on growth parameters, H2O2 and MDA content and activity of SOD, CAT, APX, GR, DHAR enzymes and also ASA, DHASA, proline and total soluble sugar. The results showed that maximum amount of RWC, root and shoot length reached in 0.01 mM SA. H2O2 and MDA content increased under SA treatment. APX and CAT activity initially decrease in low concentrations of SA and then increased in toxic level (0.1 and 0.5 mM SA). Activity of GR, DHAR, SOD, ASA, DHASA, proline and total soluble sugar gradually increased compared with control plants. These results indicate that plants for defense against oxidative stress cause by ROS production change and induce proline, total soluble sugar and ascorbate-glutathione cycle enzymes and compounds. In this study, the concentration of 0.01 mM SA with the highest growth indices and the least amount of stress as the optimal concentration in the plant is introduced.