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Genetic Modification Isn't An Unnatural Process, Borlaug Says

Norman Borlaug has a point to insert into the debate over genetically modified foods: Ordinary leavened bread is made from wheat that carries the genes of three plant species. And the genetic engineering didn't happen in the past decade or even the past millennium. Nature spliced the genes before the rise of the Roman Empire.

"Genetically modified organisms are the result of a natural process that was going on long before humans became involved," said Norman Borlaug, 84, who won the Nobel Peace Prize in 1970 for his achievements in breeding high-yielding wheat.

He now teaches crop history at Texas A&M University when he isn't in Africa working with former President Jimmy Carter to help farmers extract higher yields from their crops under a project called Sasakawa-Global 2000.

Borlaug insists that there has been "too much emotion and too little science" in the reaction to crops that are genetically modified in laboratories.

Species barriers are significant in nature, but not inviolate, he said. Take wheat, for example.

When primitive farmers selected the wild grass that came to be known as wheat, they sowed a plant that had seven chromosomes in its pollen stage.

Somehow that wheat crossed with another plant to create a new species with 14 chromosomes. Borlaug calls it "spaghetti wheat." It was the leading commercial grain until Roman times, and we use its descendants today for pasta and unleavened bread.

Then yet another species emerged with 21 chromosomes. We know it today as "bread wheat," Borlaug said. "It had crossed again, by itself, to another wild grass."

Over the centuries, farmers and plant breeders have tried to mimic nature's creativity, he said. As a result, almost all crops under cultivation today are the result of shuffled genes.

Borlaug learned how to insert new genes into plants at the University of Minnesota, where he earned a Ph.D in plant pathology in 1941. Three years later, he took a job helping Mexican farmers get rid of a disease called stem rust that had wiped out their crops three years in a row. Borlaug fortified the Mexican wheat with genes from resistant varieties in Minnesota, North Dakota and Canada.

At the time, cross-breeding plants to get the genes for a desired trait was a slow process of trial and error.

"When we said we were transferring a gene for stem-rust resistance, there were a considerable number of others that were on the same parts of the chromosome that were trailing along with it," he said.

Many of those tag-along genes gave the plants traits that farmers didn't want. To get rid of them, breeders developed a system of "backcrossing."

In Mexico, for example, Borlaug would cross a local variety with a Minnesota wheat, grow the plants to maturity, plant their seeds, determine which of the offspring resisted stem rust and cross those plants back to the Mexican varieties. The technique of the day called for repeating the process again and again until the plants were similar to the Mexican varieties but also resisted stem rust.

It generally took 10 generations or more - that is, 10 growing seasons - to get only the genes of interest with nothing else tagged along, Borlaug said. In Mexico, he shortened the time by shuttling between the north and the south to sneak in two growing seasons a year.

The key difference today is that plant breeders can isolate precisely the genes they want and insert them directly into plants. Thus, they "aren't carrying along a lot of other garbage that we knew was there but we had no way of controlling," he said.

Those calling for caution in using the products of modern genetic engineering on farms argue that there is another huge difference: Scientists are combining genes from species that would have almost no chance of crossing in the wild.

The Union of Concerned Scientists put it this way in a primer on the technology: Formerly, someone who wanted a purple cow could breed one only if purple genes were available in a cow or a near relative to cows. But a modern-day genetic engineer has no such restrictions. "If purple genes are available anywhere in nature - in a sea urchin or an iris - those genes could be used in attempts to produce a purple cow."

Borlaug acknowledged that there has been a significant leap from his example of crossing wild grasses. The appropriate response, he argued, is not to reject the crops but to make sure they are thoroughly tested under government regulation. The varieties available, he noted, have been adequately tested by their makers under standards carefully set by three federal government agencies in consultation with many scientists.