中文摘要：

本文以番茄为材料,研究H2O2和MAPK在BR诱导的抗氧化防护系统中的作用。结果表明,外源BR提高抗氧化防护酶SOD和CAT活性;而这种诱导机制被H2O2产生抑制剂二苯基碘（DPI）和MEK1/2专一抑制剂PD98059阻断。进一步研究发现：BR能够诱导细胞质外体H2O2的产生,这种诱导被PD98059抑制;BR能够活化一种49kDaMAPK,这种活化被DPI抑制。本研究结果证实细胞质外体H2O2和MAPK候选激酶（49kDaMAPK）信号参与BR诱导的抗氧化防酶途径,且两者之间存在交互作用。

英文摘要：

In this study,the role of H2O2 and MAPK（mitogen-activated protein kinase） in BR（brassinosteroid）-induced antioxidant defense system were investigated in leaves of tomato,Lycopersicom esculentum Mill..The results showed that exogenous BR increased antioxidant defense enzymes SOD and CAT activities.However,the induction mechanisms were blocked by pre-treatment with the apoplastic H2O2 production inhibitor DPI and the mitogen-activated protein kinase kinase（MEK1/2） specific inhibitor PD98059.Further studies showed that BR was able to induce the production of apoplastic H2O2 and the activation of a 49-kDa MAPK,which were inhibited by PD98059 and DPI,respectively.The results suggest that the interactive cross-talk between apoplastic H2O2 signal and a candidate MAPK kinase（48 kDa MAPK） signal are involved in BR-activated antioxidant defense enzymes.