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EC-sponsored Research on Safety of Genetically Modified Organisms - A Review of Results
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image Analysis of gene transfer between micro-organisms and plants

Background and objectives (1)

The intentional release of genetically modified organisms (GMOs) into the environment has led to increased interest in possible interactions that may occur between resident organisms. Of particular interest is the potential of introduced genetic material to transfer, stably integrate into and be expressed in resident species. This raises issues of the potential ramifications on the environment and human health. Classical microbial genetic studies carried out under laboratory conditions have identified a number of mechanisms whereby genetic information can be transferred and established in closely related, recipient species. 'Trans-kingdom' gene transfer from bacteria to eukaryotes has also been demonstrated in the laboratory.

In the absence of documented proof of genetic transfer from plants to bacteria, our aims were to construct transgenic plants expressing ‘foreign’ DNA and assess possible gene transfer between plants and micro-organisms.

(1) This project was a direct follow-on from EC project: BAP-0422/0475/0476/0483/0486.

Approach and methodology

It is unknown whether genetic transfer from plants to bacteria occurs under natural conditions, so several different environments were used in the consortium to look for evidence of gene transfer. These included a tobacco plant tumour, field conditions, conventional bacterial growth media, and in laboratory microcosms designed to mimic and allow experimental manipulation of the physiochemical characteristics of the soil. In Bielefeld we analysed transgenic plants containing the aacC1 gene conferring resistance against gentamicine to bacteria and the luciferase gene conferring bioluminescence to plants and bacteria. Transfer of these genes to bacteria was detected by selecting on antibiotica-containing media and via tests for bioluminescence. We used the soil bacterium Agrobacterium tumefaciens as a biological tool to detect plant-bacterium DNA transfer since this bacterium is well known to be the biological agent of the crown gall disease which is caused by the transfer of a couple of bacterial genes into plant cells. The mechanisms of this transformation via DNA transfer obviously make A. tumefaciens a good candidate for the investigation of the DNA transfer from the plant to bacteria. In addition, conventional transformation assays were carried out with Agrobacterium tumefaciens and plasmid DNA carrying the aacC1 gene to test the influence of several factors typical for Agrobacterium-driven plant transformation, e.g. acetosyringon (induction of the bacterial vir genes), linear or single-stranded plasmid DNA, and plant tissue homogenates.

Main findings and outcome

No evidence for gene transfer from plants to bacteria (A. tumefaciens) in a plant tumour was obtained. Control experiments ensured that the genes under investigation were active in bacteria if transfer would have occurred.


These studies have provided us with a better understanding of the DNA plasmid transfer. The finding that sequences of plant origin were not transferred to a significant frequency clearly demonstrated that natural gene transfer from plant to A. tumefaciens is rather unlikely notwithstanding the sophisticated mechanisms allowing this bacterium to transfer DNA to the plant efficiently.


Major publications

Gascon J., Oubina A., Perez-Lezaun A., Urmeneta J., “Sensitivity of selected bacterial species to UV-radiation”.
Curr. Microbiol., 30 (3), 1995, pp. 177-182.

Lafuente R., Maymo-Gatell X., Mas-Castella J., Guerrero R., “Influence of environmental factors on plasmid transfer in soil microcosms”.
Curr. Microbiol., 32 (4), 1996, pp. 213-220.

Paget E., Simonet P., “On the track of natural transformation in soil, FEMS”.
Microbiol. Ecol., 15 (1-2), 1994, pp. 109-117.
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Contract number

October 1991 – March 1994

C.J. Thompson
Institut Pasteur
Paris (FR)



R. Guerrero
Universidad de Barcelona (ES)

A. Pühler
Universität Bielefeld (DE)

P. Simonet
Université de Lyon
Villeurbanne (FR)

A.S. Tsiftsoglou
Aristotle University of Thessaloniki (GR)

M. Lebrun
Rhône-Poulenc Agrochimie
Lyon (FR)

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