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| Credit: Univ. of GA Plant Pathology Archive, Univ. of GA, Bugwood.org |
Scientists figured out that Agrobacterium was causing the disease by getting it's DNA integrated into its hosts chromosomal DNA. The plant would express that DNA just like it would it's own DNA, except these new genes told the plant to form this tumor like growths.
Agrobacterium seemed like a great tool to use to incorporate DNA the scientist chooses instead of the virulent DNA. Agrobacterium has a TI plasmid (Label C in the figure below) that contains the bacterium DNA that will be incorporated into the target plant along with other DNA sequences the bacterium uses to actually infect the plant.. This small segment of DNA that is actually transformed into the host cell's chromosome is called the T-DNA, which is part of the TI plasmid. So scientists just replaced the Agrobacterimum's infection causing T-DNA with a gene of interest. The Agrobacterium is no longer pathogenic and cannot cause disease. Just for those concerned, even in its pathogenic form it does nothing to humans except in a few very rare cases where an individual cases where a human is very immune compromised. . And when a GMO plant is sold there is no Agrobacterium present anymore.
What is can do now is naturally insert a gene of interest into your target crop like rice, wheat, maize, soy, cotton, etc. Usually it is as simple as just letting your target plant material soak in the Agrobacerium for a defined amount of time. That plant material becomes transformed with your new gene when the new gene incorporates into the target's chromosomal DNA. Tissue culture techniques are used to grow the target material into a plant that we call a T0 plant. The T0 plant will express the new gene that is now parts of its DNA. When expressed that gene may protect crops from pests or give herbicide tolerance.
This ingenious system has been used for years to transform crops by biotech corporations and universities. Biolistics in the form of the gene gun is the man-made form of transformation, but as a scientist I have found that nature almost always does things better. Agrobacterium is a very safe, efficient, and natural system that Nature developed long before we even thought of the concept.
Agrobacterium seemed like a great tool to use to incorporate DNA the scientist chooses instead of the virulent DNA. Agrobacterium has a TI plasmid (Label C in the figure below) that contains the bacterium DNA that will be incorporated into the target plant along with other DNA sequences the bacterium uses to actually infect the plant.. This small segment of DNA that is actually transformed into the host cell's chromosome is called the T-DNA, which is part of the TI plasmid. So scientists just replaced the Agrobacterimum's infection causing T-DNA with a gene of interest. The Agrobacterium is no longer pathogenic and cannot cause disease. Just for those concerned, even in its pathogenic form it does nothing to humans except in a few very rare cases where an individual cases where a human is very immune compromised. . And when a GMO plant is sold there is no Agrobacterium present anymore.
What is can do now is naturally insert a gene of interest into your target crop like rice, wheat, maize, soy, cotton, etc. Usually it is as simple as just letting your target plant material soak in the Agrobacerium for a defined amount of time. That plant material becomes transformed with your new gene when the new gene incorporates into the target's chromosomal DNA. Tissue culture techniques are used to grow the target material into a plant that we call a T0 plant. The T0 plant will express the new gene that is now parts of its DNA. When expressed that gene may protect crops from pests or give herbicide tolerance.
This ingenious system has been used for years to transform crops by biotech corporations and universities. Biolistics in the form of the gene gun is the man-made form of transformation, but as a scientist I have found that nature almost always does things better. Agrobacterium is a very safe, efficient, and natural system that Nature developed long before we even thought of the concept.
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| http://en.wikipedia.org/wiki/Agrobacterium_tumefaciens |
Transfer of T-DNA into plant cell by Agrobacterium tumefaciens
- A: Agrobacterium cell
- B: Agrobacterium DNA
- C: Ti Plasmid
- a: T-DNA
- b: vir genes
- c: replication origin
- d: opines catabolism
- D: Plant cell
- E: Plant mitochondria
- F: Plant chloroplast
- G: Plant nucleus
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