A soil-inhabiting, plant pathogenic bacterium. Agrobacterium tumelaciens. Infects broad-leaved dops inducing tomato,soybean,sunflower and cotton, but not the careals it tumours called crown galls.
Tumour formation is inducted by its plasmid, which is therefore called T i-plasmid (Ti for tumour inducing) The Ti-plasmid integrates a segment of its DNA, termed T-DNA. into the chromosomal DNA of its host plant cells. the T-DNA causes tumours As g ene trasnfer occurs without human effort, the bacterium is known as natural genetic angineer of plants.
Plant molecular biologists have started using Ti-plasmid as vectors to trasnfer foreign genes of interest into the target plant cells. they use a version of the plasmid from which tumour forming gene has been elemnated. the transformed bacteria do not cause disse ase. but still deliver genes of interest into a variety of plants.
