Changes of Antioxidant Enzymes during Salt Stress on Seedling Leaves of Tomato (Lycopersicon esculentum L.)
[Objective] The objective of this study was to assess the role of the antioxidant defense system of tomato (Lycopersicon esculentum L.) seedling leaves during exposure to salinity.[Method] Two-day-germination tomatos were treated with 120 mmol/L NaCl for 7 days to determine antioxidant enzyme activities.Denaturing and non-denaturing electrophoresis were used for isozyme profiles.The activities and isozyme profiles of glutathione reductase (GR),glutathione peroxidase (GPX),catalase (CAT),superoxide dismutase (SOD) and ascorbate peroxidase (APX) were monitored.[Results] The results indicated that NaCl stress induced higher activities of CAT and APX,and lower activities of GR and GPX,but the changes in SOD activity were nonsignificant at the 120 mmol/L NaCl concentration.The results of isoforms of GR and GPX in leaves of the control assessed by SDS-PAGE,revealed that two GR isoforms with molecular masses of 50 kDa and 46 kDa,and three GPX isoforms with molecular masses of 60,50 and 48 kDa.Under salt-exposure,the 46 kDa isoform of GR was disappeared,and the intensity of two GPX isoform bands (48 kDa and 60 kDa) was notably suppressed.In addition,the analysis of isozyme pattern in leaves of controls showed tWo and three major bands of CAT and APX.CAT I,CAT Ⅱ] and APX Ⅱ increased strikingly in 120 mmol/L NaCl treatment.In control leaves we observed three isoforms of SOD which were not changed under salt-exposure.[Conclusion] The involvement of CAT and APX was main antioxidant scavengers under present conditions of salt stress.
salinityantioxidant enzymesLycopersicon esculentum L.
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