A tumor-inducing plasmid (Ti plasmid) is a plasmid found in pathogenic species of Agrobacterium. Ti plasmid contains a region called T-DNA which is replaced by our gene of interest (nematode specific genes) and Agrobacterium is then allowed to infect the tobacco plant. When Agrobacterium infects the tobacco plant, gene of interest (nematode specific genes) also gets inserted in tobacco.