Prof. Godelieve Gheysen
Departement of Biotechnology, Ghent University
GMO’s mimick what happens in nature: T-DNA from Agrobacterium is present in sweetpotato
Godelieve Gheysen, Faculty of Bioscience Engineering, Ghent University
Horizontal Gene Transfer (HGT) is a potential creative force in genome evolution but it is also being used to generate improved plants. During the development of GMO’s, Agrobacterium is routinely used in the lab to transfer DNA into plants. Examples of natural HGT from bacteria to plants include Agrobacterium and representatives of the genera Nicotiana (including tobacco) and Linaria.
Nevertheless, such findings were not associated with domesticated edible crops until our discovery of T-DNAs from Agrobacterium in the cultivated sweet potato (Ipomoea batatas) genome. One T-DNA (T-DNA1) is inserted in an F-box gene while another (T-DNA2) is present in the gene for a mitochondrial protein. T-DNA1 was detected in all tested cultivated sweet potatoes and in some wild relatives. T-DNA2 occurs in about 1/5 of the cultivated sweet potatoes and in some wild relatives. We have confirmed that the insertion site of T-DNA2 is the same in the different species and therefore this transformation by Agrobacterium must have happened in a progenitor species more than a million years ago. This example of HGT adds to the increasing evidence from genome studies that unrelated organisms exchange DNA in nature. It also puts the GMO-discussion on DNA transfer across species borders in a new perspective.