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Ayalew examines plant tissue regeneration from leaf discs transformed with the plant marker gene. Photo by R. Maxey, The University of Tennessee Institute of Agriculture. Download this photo (600 KB) Click here for a PDF explaining two theoretical pathways for horizontal gene transfer (89 KB)

(KNOXVILLE, Tenn.) – A team of researchers with the University of Tennessee has discovered a unique plant gene that may alter research and production of genetically modified crops.

In a paper to be published in the September issue of Nature Biotechnology, UT plant scientists Mentewab Ayalew and Neal Stewart document the first use of a plant gene as an antibacterial selection marker. Selection markers are invaluable tools for producing genetically modified plants.

"Our discovery of a plant-based selection marker will certainly impact the public debate over the use of genetically modified crops," Stewart said. "It has the potential to make genetically modified crops more attractive to markets overseas."

Since the 1980s researchers have been pairing genes for desirable plant traits with bacterial markers and inserting them into target plants. By using bacterial genes resistant to certain antibiotics as markers, researchers can separate genetically modified plants from parent tissue. The genetically modified plants exposed to the antibiotics live while parent tissue is killed.

However, inserting bacterial selection markers into plant genomes has raised questions about the possible transfer of the engineered genes. The theoretical risk is an increase in antibiotic resistance in bacteria that might come in contact with modified plants, which could lead to human health risks.

"Because our marker originates from a plant, it is highly unlikely any horizontal gene transfer would result in antibiotic-resistant bacteria," Stewart said.

Concerns over the biosafety of genetically modified crops are among the chief objections to their production and sale. Both researchers say their discovery will influence scientific debate about genetically modified crops and be a valuable open-source tool for researchers worldwide.

Stewart holds the Racheff Chair of Excellence in Plant Molecular Genetics in the UT Institute of Agriculture and is the author of the book Genetically Modified Planet (Oxford University Press, 2004). Ayalew holds a post-doctoral appointment in the UT Department of Plant Sciences.

Their paper, "Overexpression of an Arabidopsis thaliana ABC transporter confers kanamycin resistance to transgenic plants," appeared August 21 in the advance online publication of Nature Biotechnology.

Further research involves monitoring the gene's expression in canola and other mustard species as well as investigating its activity in bacteria.

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Online at http://www.nature.com/nbt

Contacts:
Neal Stewart
The University of Tennessee
Department of Plant Sciences
USA
(865) 974-6487

Patricia McDaniels
The University of Tennessee Institute of Agriculture
Marketing and Communications Services
USA
(865) 974-7141