Agrobacterium and Plant Interactions Crown gall and Hairy root Crown gall: caused by Agrobacterium tumefaciens which carries a Ti(Tumor induction) plasmid that promotes the crown gall formation Hairy Root: caused by Agrobacterium rhizogenes which carries a Ri plasmid that leads to hairy roots formationAgrobacterium and Plant Interactions: Crown gall and Hairy Root Crown gall: caused by Agrobacterium tumefaciens which carries a Ti (Tumor induction) plasmid that promotes the crown gall formation Hairy Root: caused by Agrobacterium rhizogenes which carries a Ri plasmid that leads to hairy roots formation