中文摘要：

将编码大豆凝集素的lec—s基因插入植物表达载体pBll21中，构建植物重组表达质粒pBI121：：lec—S。由根癌土壤杆菌EHAl05介导的叶盘法转化烟草，获得了转基因烟草株系。PCR和RT—PCR检测证明lec-S基因已转入烟草植株中。接种烟草花叶病毒（Tobaccomosaicvirus，TMV）进行抗病性试验结果表明，转基因烟草叶片上的病斑数显著减少，说明转基因烟草表现出对TMV的抗性。定量RT—PCR检测发现，接种TMV后，抗病防卫基因（PR-la、GSTl、Pal和hsr515）在转基因烟草叶片中显著上调表达。这些结果表明，大豆凝集素基因lec—S转化烟草可对TMV产生抗性，其作用机制可能在于lec—s基因参与了植物的防卫信号通路，诱导了抗病防卫基因在转基因植株体内的表达，增强了植株对TMV的系统抗性。

英文摘要：

The lec-s gene encoding soybean lectin was inserted into transgenic vector pBI121. The leaf discs from tobacco were transfected by Agrobacterium tumefaciens strain EHA105/pBI121 ： ： lec-s. Kanamycin-re- sistant transformed plants were obtained. PCR and RT-PCR analyses confirmed successful integration of the foreign gene into the genome of the T1 generation tobacco plants. Bioassays revealed that the resistance of transgenic plants to Tobacco mosaic virus （TMV） was increased; lesion numbers on leaves caused by TMV were m~kedly reduced in transgenic plants comparing with the controls. Quantitative RT-PCR analysis indica- ted that four defense-related genes, PR-la, GST1, Pal, and hsr515, were up-regulated in transgenic lines in- oculated with TMV. The up-regulations of these defense-relate genes were not observed in leaves of control plant after inoculation. The results suggested that lec-s gene might play a role in the regulation of plant defense responses through the induction of downstream defense-related genes after the recognition of microbial patho- gens, thus the transformed tobacco plants with lec-s gene could enhance the resistance to TMV.