将柽柳（Tamarix sp.）金属硫蛋白基因（MT1，GenBank登录号：AB298390）插入植物表达载体pBI121，取代花椰菜病毒35S启动子下游的gus基因，利用农杆菌（Agrobactrium tumefaciens）介导法将MT1导入烟草（Nicotiana tobacum）基因组。对具有卡那霉素抗性，且经PCR-Southern检测和Northern杂交表现阳性的转基因株系进行抗Cd2+分析表明，金属硫蛋白基因的过量表达提高了转基因植株的抗Cd2+能力，在含200 µmol L-1和400 µmol L-1 Cd2+的MS培养基上，转基因植株的株高和鲜重均明显优于非转基因株系；在生理性状上表现为转基因植株MDA含量及POD活性明显低于非转基因株系，叶绿素含量和SOD活性比非转基因株系明显增加。
A metallothionein gene (MT1, GenBank accession No. AB298390) from Tamarix sp. was directionally cloned and transformed into the pBI121 binary vector, in place of the XbaⅠ–SacⅠGUS cassette. The Cauliflower mosaic virus (CaMV) 35S promoter/-nopalin synthase terminator system and kanamycin resistant gene NPTⅡ (neomycin phosphotransfers Ⅱ) were used for these constitutive expression systems. The plasmid was then introduced into Agrobacterium tumefaciens (strain EHA105) by electroporation. Tobacco (Nicotiana tobacum) primary transformants were produced by leaf disc transformation. Southern and Northern hybridization indicated that exogenous gene was integrated into the transgenic tobacco plants, and correctly expressed under the control of 35S promoter. The Physiologic Characters of transgenic tobacco for Cd2+ tolerance was studied. The results showed that the activity of SOD and concentration of chlorophyll were increased, whereas the activity of POD and accumulation of MDA were decreased in transgenic tobacco than in non- transformant. Enhanced growth of transgenic tobacco was observed at the early development stages, resulting in plant height and fresh weights significantly greater than those of non-transformant. These results demonstrate that the exogenous metallothionein expression increase the ability of cleaning up reactive oxygen than that of non-transformant, showing a stronger tolerance to Cd2+ stress.
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