Novartis pins hopes for GM seeds on new marker System

Novartis pins hopes for GM seeds on new marker System

Nature 406, 924 (2000) © Macmillan Publishers Ltd.

QUIRIN SCHIERMEIER

[MUNICH] The multinational company Novartis Seeds last week launched a campaign to gain

worldwide support from the plant-science community for its new marker-gene system,

Positech.

The campaign follows the company's recent announcement that it plans to phase out

antibiotic-resistance marker genes in its future products, in an attempt to restore public

confidence in the safety of genetically modified foodstuffs.

Plant geneticists use marker genes to monitor the transformation of plant cells after a foreign

gene has been introduced into a plant along with the marker. The most commonly used

markers are antibiotic- or herbicide-resistance genes, which protect the cells against an agent

introduced to kill those that have not taken up the desired DNA.

But concerns have been triggered about the potential threat to public health. There are fears

that antibiotic resistance genes could 'jump' from transgenic plants to microorganisms such as

gut bacteria, increasing antibiotic resistance in humans.

The Positech marker system uses transformed plant cells that contain the gene encoding the

enzyme phosphomannose isomerase (PMI). In the selection process, only the cells that take

on the PMI trait can survive in a culture in which they are fed only mannose, a simple sugar.

Novartis says the system has been tested successfully with transgenic maize and wheat.

"Positech is well along on the development path," Wally Beversdorf, head of research and

development at Novartis Seeds, told last week's International Crop Sciences Congress in

Hamburg. "We will have regulatory packages containing PMI probably within 12 to 18

months."

Basic researchers, who can use 'Positech' without royalties, have welcomed the launch. "The

availability of less controversial marker genes would certainly improve the acceptance of our

research, and cool down the public debate," says Uwe Sonnewald, head of molecular cell

biology at the Institute for Plant Genetics and Crop Plant Research in Gatersleben, Germany.

But environmental groups say that phasing out antibiotic-resistance marker genes would only

be a small improvement. Greenpeace has called Novartis' campaign "mere propaganda" aimed

at easing consumer concerns about genetically modified foods. "Other important issues, such

as the ecological impact of gene transfer into the environment, are ignored," says a

spokesman.