[Formation of deletional derivatives of the Ti-plasmid pGV3850 in a conjugative transfer from Agrobacterium tumefaciens to Escherichia coli].

The process of the transfer of the Ti-plasmid vector pGV3850 with the plasmid pBR322 inserted into the T-DNA region from Agrobacterium tumefaciens to a non-plasmid strain of Escherichia coli was studied. The transferred Ti-plasmid was found to be exposed to deletions and formed a wide range of derivatives with a size ranging from 3-4 kb to 50 kb, maintained in E. coli due to ColE1-replicon. The Ti-plasmid is also inserted into the chromosome of the recipient bacterium with at least a 100-fold lower frequency than the formation of deletional derivatives. It was shown that the induction of vir genes controlling the transfer of T-DNA into plants has no appreciable effect on the efficiency of obtaining transconjugates in mating with E. coli. The deletion of the genetic material of megaplasmids with the inserted functional site OriV ColE1, as a result of the conjugative transfer from cells of different bacteria to the cells of E. coli, was proposed for molecular cloning.