Researchers from Bristol University in the United Kingdom announced a recent discovery of a relatively new route from which GM genes may escape into the environment. It may further help determine the rate and the range of spread that GM genes may possibly reach and the consequent effects that could arise.
What the researchers may refer to “escape” is the possible horizontal gene transfer of GM genes through infection or multiplication, regardless of the barriers from one species to another. The researchers from Bristol University have been able to show that plant wounds that can be created by abrasion, insect bites and other mechanical means can become possible entry points for gene transfer. This may be made more possible by the actions of the soil bacterium, Agrobacterium tumefaciens.
A. tumefaciens is a pathogen known to cause crown gall disease in plants. It is unique among natural plant pathogens in the way that it carries out trans-Kingdom horizontal gene transfer during an infection. The disease causing strain of A. tumefaciens carries a tumor-inducing plasmid that allows the horizontal gene transfer of a part of said plasmid, the T-DNA, into a plant’s own cell genome when the disease causing system of the pathogen is activated. This unique function has also been widely used by biotech companies in order to develop genetically modified organisms or GMO’s.
As A. tumefaciens is a type of pathogen that usually infects plants through wounds, it may be possible that the pathogen may encounter other species of microorganisms, including pathogenic fungi that may use the same method in order to gain entry into a plant. Plant wound sites usually are found abundant with the hormone acetosyringone, making it the area primed for T-DNA transfer by pathogens.
In order to investigate this possibility, the researchers used wilt-causing fungus Verticillium albo-atrum that may also be a strong candidate for encounters with the A. tumefaciens in an infected plant. Previous experiments have shown that V. albo-atrum can’t transform into A. tumefaciens without the presence of acetosyringone. If the fungus is presented with A. tumefaciens in a plant tissue and a transformation occurs, it must be that the wound hormone may be supplied by the plant itself.
The researchers used peeled and sliced potato tubers and carrots as well as cut leaf and stem sections of tobacco as plant tissues for testing. After being sterilized, the plant tissues were then inoculated with both A. tumefaciens and V. albo-atrum and then left at room temperature in a covered agar dish for a period lasting from a minimum of 8 days to a maximum of 42 days.
The researchers were then able to obtain successful transformants of V. albo-atrum from all kinds of the plant tissues tested. The transformants were confirmed with the use of molecular genetic analyses.
The researchers concluded in their study that this may raise some interesting questions whether the ability of the A. tumefaciens pathogen to infect in the natural environment may be more than just being limited to plants. The said pathogen is known to survive within plant tissue and may be found in regenerated transgenic plants. This study may have certain implications in the risk assessment of GM plants.