State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer DNA to plant cells.
Agrobacterium is a bacterium that infects plant tissues by transferring its plasmid T-DNA to the plant genome. This property of Agrobacterium is exploited in the biotechnology industry.
The desired gene that has to be to transferred to a particular plant is inserted in a plasmid T-DNA of Agrobacterium. Then, this engineered Agrobacterium is allowed to infect that particular plant, so that it can transfer the desired gene to the plant genome through its T-DNA. In this way, the desired changes are made in the plant.