Mechanisms of unintended transfer of Agrobacterium chromosomal DNAs (AchrDNAs) to plants and their extent, consequences, detection and elimination

• Applicant: Dr. Bekir Ülker
• Subject Area: Plant Genetics and Genomics
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 190124055

Agrobacterium tumefaciens is the causative agent of crown gall disease in plants. As a consequence of natural gene transfer from the pathogen to the plant cells, infected plant tissue produces tumours and synthesizes nutrients, which only Agrobacteria are able to use. This natural gene transfer mechanism has been successfully exploited by researchers in generating transgenic plants and gave rise to the Agrobacterium-mediated transformation method, which has been the method of choice when transforming plants. This method has also been successfully used in transforming other organisms including human cells. Numerous commercial transgenic crops generated using this technology are cultivated in several countries to be used in food, feed or other industries. We have discovered that besides genes located on the transferred DNA, sometimes other large Agrobacterium chromosomal DNA fragments (AchrDNAs) are unintentionally transferred from the bacteria to plants. The mechanism, by which AchrDNA transfers to plants remains unknown. Although detection of AchrDNA in plants has important implications on our knowledge of horizontal gene flow between species, it has negative implications in regulation of genetically modified plants. We are interested in determining, whether AchrDNA transfer happened in nature or not. Similarly, we want to determine, whether transgenic crops released to farmers and producers contain unintentionally introduced AchrDNA in their genomes. Most importantly, we are interested in determining the mechanism of AchrDNA transfer to plants. Finally, we would like to study biosafety consequences of unintentional bacterial chromosomal DNA transfer to plants and develop solutions to how to detect, eliminate or completely avoid this undesired bacterial DNA transfer.

• DFG Programme: Research Grants