The answer is The foreign DNA is placed in a biological vector for cloning.
After target genes are identified and isolated, they are usually inserted into a transfer factor. In the process of creating genetically modified crops, the transfer factor is plasmid (a circular DNA molecule) from a soil bacterium Agrobacterium tumefaciens. Therefore, the transfer vector in which the foreign DNA is placed is a biological vector. It is not artificially produced but isolated from the living bacterium.
