Eight DNA insertion events of Agrobacterium tumefaciens Ti-plasmids in isogenic sunflower genomes are all distinct.

We investigated whether the same or different T-DNA insertions occur every time Agrobacterium tumefaciens, the octopine type strain pTi 15955 strr, infects genetically identical sunflower plants. Eight newly established crown gall tissue culture lines were analyzed for their T-DNA content. Our data showed that all isogenic crown gall callus DNA produced distinct hybridization patterns. These eight patterns were also different from three standard lines included for comparison. In addition, all the tumor lines analyzed produced octopine, albeit in different quantities, and five produced agropine and mannopine. We concluded, that each A. tumefaciens crown gall tissue line derived from isogenic sunflower plants contained a distinct insertion pattern of T-DNA. Possible causes and reasons for this diversity will be discussed.