Researchers at Oregon State University (OSU) have recently developed a way to genetically engineer plants for total resistance to crown gall disease, a tumor forming disease that occurs in dicotyledonous plants as a result of infection by the bacterium Agrobacterium tumefaciens.
The system has been tested with tobacco plants and apple trees and appears to provide virtually complete protection from this plant disease.
OSU scientists believe this genetic technology could be applicable to a wide variety of other fruit, nut and ornamental trees and plants — everything from grapes to roses, apple trees and chrysanthemum — which can suffer impacts from crown gall disease according to an article from OSU research and development.
The commercial use of this technology may be slowed somewhat by the cost of field trials and the significant regulatory hurdles that face any use of a genetically engineered plant according to researchers.
Crown gall disease is caused by Agrobacterium tumefaciens, bacteria found in soils that can genetically transform plant cells to grow as tumors. The bacteria may infect a plant when it has a cut. The benign tumors produced by an infected plant are typically found on plant roots.
With the new development, the “gene silencing” technique developed by OSU researchers essentially tricks plants into sensing that they are being attacked by a virus, which they then destroy with their own defense systems. This approach allows crown gall bacteria to infect a plant, inject tumor-inducing genes into the plant's DNA and then begin to express RNA as the plant begins a biochemical process that would eventually lead to uncontrolled growth of a tumor. But the genetically engineered plants make double-stranded RNA, instead of the single-stranded RNA ordinarily produced. The plant recognizes the double-stranded RNA as a virus, which it has the capacity to destroy with its own natural defense systems. So even though the plant has been infected by crown gall bacteria, the process of tumor formation is interrupted before any damaging effects can occur according to OSU researchers.