Agrobacterium tumefaciens

Soil bacterium naturally able to transfer parts of its genetic material to plant cells. It has thus been used as a tool for genetically engineering plants.

Agrobacteria are natural plant parasites. To create a suitable environement for themselves, they insert genes into plant hosts, which cause them to form a proliferation of cells near the soil level (crown gall). The genetic information for tumour growth is encoded on a mobile, circular DNA fragment (plasmid).

When Agrobacterium infects a plant, it transfers so-called T-DNA to a random site in the plant genome.

The natural ability of Agrobacterium tumefaciens to transfer genes is used in genetic engineering. The bacterium is used as a means of transporting foreign genes into plants (vector). To do this, the bacterial T-DNA is cut out of the bacterial plasmid and replaced with the desired foreign gene.

Transferring genes with agrobacteria is a commonly used and reliable method. It works especially well for dicotelydenous plants like potatoes, tomatoes, and tobacco. Agrobacteria are less suitable for introducing foreign genes to crops like wheat and maize.