Q.What is the importance of Agrobacterium tumefaciens ?

Agrobacterium tumefaciens is a soil bacterium that, entirely on its own, naturally transfers a defined segment of its own Ti (tumour-inducing) plasmid - the T-DNA (transfer DNA) - into the genome of a wounded dicot plant cell, which is what causes the crown gall tumours this bacterium is known for; this natural talent for inserting foreign DNA into a plant's genome earns it the nickname 'the natural genetic engineer of plants'. In genetic engineering, the Ti plasmid's own disease-causing DNA is replaced with the gene actually of interest (e.g. a Bt insect-resistance gene) plus a selectable marker gene (commonly npt II, conferring kanamycin resistance), cloned into the T-DNA region in place of the unwanted native sequences - so the re-engineered Agrobacterium delivers the desire …