This review chronicles the development of the plant binary vectors of Ti plasmid in Agrobacterium tumefaciens during the last 30 years. A binary vector strategy was designed in 1983 to separate the T-DNA region in a s...This review chronicles the development of the plant binary vectors of Ti plasmid in Agrobacterium tumefaciens during the last 30 years. A binary vector strategy was designed in 1983 to separate the T-DNA region in a small plasmid from the virulence genes in avirulent T-DNA-less Ti plasmid. The small plant vectors with the T-DNA region have been simply now called binary Ti vectors. A binary Ti vector consist of a broad host-range replicon for propagation in A. tumeraciens, an antibiotic resistance gene for bacterial selection and the T-DNA region that would be transferred to the plant genome via the bacterial virulence machinery. The T-DNA region delimited by the right and left border sequences contains an antibiotic resistance gene for plant selection, reporter gene, and/or any genes of interest. The ColEI replicon was also added to the plasmid backbone to enhance the propagation in Escherichia coli. A general trend in the binary vector development has been to increase the plasmid stability during a long co-cultivation period of A. tumefaciens with the target host plant tissues. A second trend is to understand the molecular mechanism of broad host-range replication, and to use it to reduce the size of plasmid for ease in cloning and for higher plasmid yield in E. coli. The broad host-range replicon of VS1 was shown to be a choice of replicon over those of pRK2, pRi and pSA because of the superior stability and of small well-defined replicon. Newly developed plant binary vectors pLSU has the small size of plasmid backbone (4566 bp) consisting of VS1 replicon (2654 bp), ColE1 replicon (715 bp), a bacterial kanamycin (999 bp) or tetracycline resistance gene, and the T-DNA region (152 bp).展开更多
Virulence (vir) genes of Ti plasmids code for a specialized conjugation system that mediates the mobilization and transfer of T-DNA from Agrobacterium to the genome of higher plants. This system is activated by a numb...Virulence (vir) genes of Ti plasmids code for a specialized conjugation system that mediates the mobilization and transfer of T-DNA from Agrobacterium to the genome of higher plants. This system is activated by a number of plant-specific phenolics, well characterized in dicots, via a two-component regulatory system. In contrast, little is known about the occurrence of vir-inducing signals in monocots, especially in the cereal crops.We have examined the effects of exudates and extracts from various rice tissues at展开更多
The composites based on the Ti O2 are potentially used in wetland pollution control. In this work, the biological effect of the Ag/Ag Br/Ti O2/Active carbon(AC) composites was studied on the plasmid DNA and Tetrahymen...The composites based on the Ti O2 are potentially used in wetland pollution control. In this work, the biological effect of the Ag/Ag Br/Ti O2/Active carbon(AC) composites was studied on the plasmid DNA and Tetrahymena membrane. The atomic force micrograph(AFM) images showed that, in the presence of the composites under illumination, most p UC18 DNA molecules showed quite different topography and were opened and relaxed circle shapes. After DNA was catalyzed for 40 min, all supercoiled and circular DNA were changed into the linear DNA molecules. The gel electrophoresis experiment confirmed the results and demonstrated the dynamic process of DNA degradation. ATR-FTIR spectra revealed that amide groups and PO2-of the phospho-lipid phospho-diester on Tetrahymena surface were oxidized in the presence of the composites under illumination. An increase in the fluorescence polarization of DPH was observed, reflecting a significant decrease in membrane fluidity of Tetrahymena.展开更多
文摘This review chronicles the development of the plant binary vectors of Ti plasmid in Agrobacterium tumefaciens during the last 30 years. A binary vector strategy was designed in 1983 to separate the T-DNA region in a small plasmid from the virulence genes in avirulent T-DNA-less Ti plasmid. The small plant vectors with the T-DNA region have been simply now called binary Ti vectors. A binary Ti vector consist of a broad host-range replicon for propagation in A. tumeraciens, an antibiotic resistance gene for bacterial selection and the T-DNA region that would be transferred to the plant genome via the bacterial virulence machinery. The T-DNA region delimited by the right and left border sequences contains an antibiotic resistance gene for plant selection, reporter gene, and/or any genes of interest. The ColEI replicon was also added to the plasmid backbone to enhance the propagation in Escherichia coli. A general trend in the binary vector development has been to increase the plasmid stability during a long co-cultivation period of A. tumefaciens with the target host plant tissues. A second trend is to understand the molecular mechanism of broad host-range replication, and to use it to reduce the size of plasmid for ease in cloning and for higher plasmid yield in E. coli. The broad host-range replicon of VS1 was shown to be a choice of replicon over those of pRK2, pRi and pSA because of the superior stability and of small well-defined replicon. Newly developed plant binary vectors pLSU has the small size of plasmid backbone (4566 bp) consisting of VS1 replicon (2654 bp), ColE1 replicon (715 bp), a bacterial kanamycin (999 bp) or tetracycline resistance gene, and the T-DNA region (152 bp).
基金the National Natural Science Foundation of China.
文摘Virulence (vir) genes of Ti plasmids code for a specialized conjugation system that mediates the mobilization and transfer of T-DNA from Agrobacterium to the genome of higher plants. This system is activated by a number of plant-specific phenolics, well characterized in dicots, via a two-component regulatory system. In contrast, little is known about the occurrence of vir-inducing signals in monocots, especially in the cereal crops.We have examined the effects of exudates and extracts from various rice tissues at
基金Funded by National Natural Science Foundation of China(No.51208043)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The composites based on the Ti O2 are potentially used in wetland pollution control. In this work, the biological effect of the Ag/Ag Br/Ti O2/Active carbon(AC) composites was studied on the plasmid DNA and Tetrahymena membrane. The atomic force micrograph(AFM) images showed that, in the presence of the composites under illumination, most p UC18 DNA molecules showed quite different topography and were opened and relaxed circle shapes. After DNA was catalyzed for 40 min, all supercoiled and circular DNA were changed into the linear DNA molecules. The gel electrophoresis experiment confirmed the results and demonstrated the dynamic process of DNA degradation. ATR-FTIR spectra revealed that amide groups and PO2-of the phospho-lipid phospho-diester on Tetrahymena surface were oxidized in the presence of the composites under illumination. An increase in the fluorescence polarization of DPH was observed, reflecting a significant decrease in membrane fluidity of Tetrahymena.
