| Systematic acquired resistance (SAR) is the most effective way in plant resistance to pathogens. When key genes in SAR signal transduction are introduced into plant by gene engineering techniques, their expression level could be enhanced and plant reaction speed to pathogen infection could be quicker, which would enhance plant disease resistance ability. Compared with traditional disease resistance gene engineering techniques, this route has no species restriction to pathogens, so it is called genetic engineering for broad-spectrum disease resistance, which has become a front field in current disease resistance gene engineering research.NDRl and NPRl genes play important roles in plant SAR. The former function locates between the activation of reactive oxygen species (ROS) and the induced salicylic acid (SA) synthesis subsequently, and NDRl gene mutant shows lower SA synthesis and SAR inducement ability when induced by pathogen, but there has been no report about its over-expression analysis yet. The function of NPRl located between SA accumulation and subsequent SAR gene expression in SAR signal transduction cascade. The corresponding mutant doesn't generate PRs and was sensitive to pathogen while the control was resistant. Transgenic Arabidopsis over-expressing NPRl gene show high resistance to many pathogens and the level of PRs(PR-l, et al) expression is also improved, and the transgenic rice with NPRl gene also enhanced its resistance to rice blight disease. In this research, two genes above were cloned from Arabidopsis using RT-PCR method. NDRl gene of Wassilewskija cultiva was different from that of Columbia cultiva in 7 bases, which led to 4 coded amino acids variations. NPRl gene of Was cultiva was identical to reported NPRl gene.The plant constitutive expression vectors driven by 35S promoter of NDRl and NPRl gene were constructed and with them tobaccos were transformed mediated via Agrobacterium. The integrations of exogenous genes to plant genome were confirmed by PCR and Southern analysis, and analysis of disease resistance showed that transgenic tobaccos with NDRl and NPRl gene had improved resistance to Phytophthora infestan and Alternaria alternata, which indicated that two genes had potential application in plant genetic engineering for disease resistance.In this research, two genes were used to develop broad-spectrum disease resistance cotton. On one hand, new data could be added for resolving the "century puzzle"-cotton Verticillium wilt, on the other hand, new experiences could be acquired for disease resistance gene engineering of other crops. Using pollen-tube pathway, land cotton cultivar Shiyuan 321 was transformed by plant constitutive expression vectors of NDRl and NPRl genes. In order to evaluate the cooperation effect of the two genes to cotton disease resistance, co-transformation tests were also done. 26 NDRl gene and 24 NPRl gene transgenic cotton series were selected by primary selection of 100 ug/ml kanamycin in Sanya from 5000 seeds acquired by injection in summer 2001 in Nanjing. 12 and 7 were proved to be positive byABSTRACTPCR and the transgenic frequencies were 0.4% and 0.35%, respectively. Verticillium and Fusarium wilt resistance t of T2 showed that cotton resistance to them was improved evidently. The further test and identification was underway. 22,000 NDR\ gene transformed seeds, 10,500 NPRl gene transformed seeds and 12500 co-transformed seeds were obtained at the beginning of 2002 in Sanya. In summer 2002, over 100 kanR plantlets were abtained after primary selection of lOOug/ml kanamycin in Verticillium wilt pool of Institute of Plant Protection, Chinese Academy of Agriculture Sciences. 5 individuals were randomly selected from each transgenic line to perform PCR test, and they showed positive results. The further test and selection of Verticillium wilt resistance and molecular analysis were underway.At the same time, the application of pathogen-induced promoters to broad-spectrum disease resistance gene engineering was also discussed in this res...
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