关键词: 盐胁迫, 抗氧化酶, 番茄

Abstract: [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 120mmol/L NaCl for 7days 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 50kDa and 46kDa,and three GPX isoforms with molecular masses of 60,50 and 48kDa.Under salt-exposure,the 46kDa isoform of GR was disappeared,and the intensity of two GPX isoform bands (48kDa and 60kDa) was notably suppressed.In addition,the analysis of isozyme pattern in leaves of controls showed two and three major bands of CAT and APX.CATⅠ,CAT Ⅱ and APXⅡincreased strikingly in 120mmol/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.

Key words: salinity, antioxidant enzymes, Lycopersicon esculentum L.