Abstract:

Agrobacterium tumefaciens is able to transfer DNA fragments（T-DNA）from its plasmid to plant cells in the form of T-complex and to integrate the T-DNA into the genome of host plants,thereby it has been used as an effective transgenic vector for plant. vbp2 is one of the three homologous genes encoding VBPs,and VBPs are involved in the transport of T-DNA by binding with the VirD2 in the T-complex. Bioinformatics analysis showed that there might be several transcriptional regulation elements in the promoter region of vpb2 gene. The vbp2 in the chromosome of A. tumefaciens was in situ replaced by the rfp encoding red fluoresce protein（RFP）using homologous recombination method,so that promoter of vbp2 controlled the expression of rfp. Therefore,the activity of vbp2 promoter can be characterized by the fluorescence intensity of the expressed RFP. The results showed that acetosyringone（AS）and rhamnose（Rha）both were able to induce the vbp2 promoter to expresse RFP. The optimal concentrations of AS and Rha for the induction were 150 μmol/L and 100 μmol/L,respectively. The test of the transcriptional activity of the truncated vbp2 promoter regions revealed that transcriptional regulation elements induced by AS and Rha were located on the regions of 165-260 bp and 126-165 bp upstream of the vbp2 gene,respectively.

Key words: Agrobacterium tumefaciens, vbp2 gene, transcriptional regulation, transcriptional activity, fluorescence protein