MODEL RELEASED. Scientist holding a specimen of a transgenic tobacco plant,Nicotiana sp.,genetically engineered by the soil bacterium,Agrobacterium tumifaciens (in culture dish in his left hand). Transgenic plants carry foreign,protein-producing genes with the potential,for example,to introduce resistance to herbicides,insects & viruses. Agrobacterium is able to hijack its host's DNA using a small strand of its own DNA known as a Ti (tumour-inducing) plasmid. T-DNA causes the plant cell to produce opines,compounds derived from amino-acids that Agrobacterium uses for energy. The Ti plasmids can be enhanced by modifications to produce healthy,fertile plants |