过表达硒代半胱氨酸甲基转移酶烟草的硒耐受特性分析

以经鉴定的硒代半胱氨酸甲基转移酶（Selenocysteine methyltransferase,SMT）转基因烟草（Nicotiana tada-cum L）和野生型烟草(NC89)为材料，置于添加不同质量浓度（０、２０、４０和６０ｍｇ／Ｌ）硒酸钠的MS培养基上进行 培养，35d后分别测定两种处理材料的过氧化物酶活性、叶绿素、鲜质量和株高等生理生化指标．结果表明：在不同质量浓度硒酸钠处理后，SMT转基因烟草和野生型烟草的叶绿素质量分数、鲜质量及株高均较各自对照明显下降，比较而言，野生型烟草的下降幅度明显大于转基因烟草；另一方面，野生型烟草过氧化物酶（Peroxi-dase,POD）活性表现强烈的应激反应，其活性明显高于转基因烟草．生长生理与表型特性表明ＳＭＴ转基因烟草具有一定的硒耐受性．

Analysis of selenium tolerance in tobacco overexpressing selenocysteine methyltransferase

The identified selenocysteine methyltransferase transgenic tobacco ( Nicotiana tabacum L) and wild-type tobacco ( NC89) were cultured on MS medium supplemented with different mass concentrations of sodium selenate ( 0, 20, 40, 60 mg/L) , the physiological indices of two kinds of test tobacco, such as peroxidase activity ( POD) , chlorophyll mass ratio, fresh mass and plant height, were determined after 35 d selenate treatment. The result showed that the chlorophyll mass ratio, fresh mass and plant height of SMT transgenic and wild type tobacco were significantly decreased compared with their respective control after in different mass concentrations of sodium selenite treatment, in contrast, the decline of wild-type tobacco was significantly greater than the transgenic tobacco. On the other hand, POD activity of wildtype tobacco was showed a strong stress response, its activity of POD was significantly higher than that of transgenic tobacco. Growth physiology and phenotypic characteristics was consistently demonstrated that SMT transgenic tobacco had some selenium tolerance.