ROLE OF HYDROGEN PEROXIDE PRETREATMENT ON DEVELOPING ANTIOXIDANT CAPACITY IN THE LEAVES OF TOMATO PLANT (Lycopersicon esculentum) GROWN UNDER SALINE STRESS

Salinity stress had adverse effects on biomass yield and water content (succulent value and relative water content) in the tomato leaves. Foliar hydrogen peroxide, malondialdhyde and phenolic contents as well as superoxide dismutase, catalase and guaiacol peroxidase activities significantly increased with increase salinity levels . In contrast, the activities of ascorbate peroxidase , glutathione reductase and polyphenol oxidase as well as ascorbate and glutathione fractions were significantly decreased. Pretreatment of tomato seeds with hydrogen peroxide resulted in a significant increase of non-enzymatic and enzymatic antioxidants, except superoxide dismutase, in the leaves under saline conditions. There were four stress protein bands of M.M. 88.8, 60.3 ,29.1 and 19.6 kDa appeared under salt stress, while pretreatment with H2O2 resulted in synthesis of only one stress protein band with M.M 17.9 kDa in the NaCl-stressed leaves . The current of this study may suggested that the primarily prominent hydrogen peroxide pretreatment appears to play a role in enhancement of scavenging the generated reactive oxygen species under saline conditions.