2006年VOA标准英语-Genetically-Modified Wheat, Cottonseed Offer Ho（在线收听）

By David McAlary
Washington
23 November 2006

Scientists have genetically engineered two crops in a way they say will help improve nutrition in poor countries. One group has boosted the levels of certain nutrients in wheat and another team has made the poisonous seeds of the cotton plant safe to eat for the first time. But opponents of genetic modification are raising objections to the changes. VOA's David McAlary reports from Washington.

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Wheat - long a staple food - could become more nutritious. U.S. and Israeli scientists have found a gene that increases protein, zinc, and iron in wild wheat.

This gene has lost its function in domesticated wheat, but the researchers report in the journal Science that they have inserted it into cultivated wheat to boost the nutrient content.

The World Health Organization estimates that more than 160 million children under age five lack adequate protein, and more than two billion people are deficient in zinc and iron.

Wheat breeder Jorge Dubcovsky of the University of California at Davis says his team's work could help the situation.

"It increases protein and it increases micronutrients - both things. So if you take that wheat to a place where people are having deficiencies in iron and zinc - the two micronutrients that are the largest deficiencies in developing countries - in the same amount of grain, you will deliver 10 to 15 percent more iron and zinc," he said.

The University of California says Dubcovsky leads a consortium of 20 public wheat breeding programs that is introducing this and other valuable genes into U.S. wheat varieties.

Meanwhile, the cotton plant might become a food source if research detoxifying its seeds proves practical.

According to a study in the Proceedings of the [U.S.] National Academy of Sciences, plant biologists in Texas have genetically engineered the crop so that the amount of the poisonous substance gossypol has been reduced in its seeds to levels safe for human consumption.

 
Cotton produces 65 percent more seed than fiber by weight, so Texas A&M University plant technologist Keerti Rathore says the cottonseed produced annually in more than 80 countries could feed a lot of people.

"The amount of protein that is stored in the cottonseed is almost 10 million metric tons roughly," he said. "That amount of cottonseed, if it can be used directly, has the potential to meet the protein requirements of about 500 million people."

Rathore's team used a technique to shut off a gene that produces the poisonous gossypol in cottonseed. Half a century ago, traditional breeding eliminated the toxin from the entire plant, but that alteration made it an easy target for insect pests.

The new genetic manipulation maintains cotton's toxic defenses everywhere except the seeds.

The Texas A&M University scientist says the new cotton - if it surmounts more research and government regulatory hurdles - would improve not only diets in poor countries, but also farmers' income.

"Not only will they get value for their fiber, but they also get higher value for the cottonseed that they are producing," he said.

Environmentalists are skeptical of the cottonseed and wheat projects. A British group called GM Freeze opposes genetically modified, or GM, foods and says genetic alterations could lead to unpredictable and potentially harmful results.

The organization's campaign director, Peter Riley, says fighting world hunger takes more than gene manipulation.

"It is extremely naive to think that by just creating a new GM crop that we're somehow going to overcome the economic and social problems that are the root of poverty and starvation in the southern countries. These aren't problems you can solve with miracle science," he said.

But pediatrician Jonathan Gitlin of Washington University School of Medicine in St. Louis, Missouri says advances in basic plant sciences are necessary to help reduce malnutrition and child mortality.

In a commentary in Science magazine, Gitlin writes that the new studies reinforce the inherent value of science for improving the lives of the youngest among us.