Final answer:
The Ti plasmid is useful in plant genetic engineering because it can introduce exogenous genes into plant genomes, which is essential for creating transgenic plants. The correct option is 2.
Step-by-step explanation:
The naturally occurring feature of the Ti plasmid that makes it useful in the genetic engineering of plants is its capability to introduce exogenous genes into plant genomes. This is because the Ti plasmid comes from Agrobacterium tumefaciens, a bacterium that naturally transfers its DNA to plant cells, causing them to develop tumors known as crown galls. In genetic engineering, researchers have harnessed this mechanism by modifying the Ti plasmid to remove the tumor-causing genes and insert desirable DNA sequences instead. These modified Ti plasmids act as shuttle vectors, enabling the transfer of specific genes into plant cells to create transgenic plants. Additionally, the presence of antibiotic-resistance genes in the Ti plasmid assists in the selection process of genetically modified cells.