The human race has been selectively breeding crops, thus altering
plants' genomes, for millennia. Ordinary wheat has long been strictly a
human-engineered plant; it could not exist outside of farms, because its
seeds do not scatter. For some 60 years scientists have been using
“mutagenic” techniques to scramble the DNA of plants with radiation and
chemicals, creating strains of wheat, rice, peanuts and pears that have
become agricultural mainstays. The practice has inspired little
objection from scientists or the public and has caused no known health
problems.
The difference is that selective breeding or mutagenic techniques tend to result in large swaths of genes being swapped or altered. GM technology, in contrast, enables scientists to insert into a plant's genome a single gene (or a few of them) from another species of plant or even from a bacterium, virus or animal. Supporters argue that this precision makes the technology much less likely to produce surprises. Most plant molecular biologists also say that in the highly unlikely case that an unexpected health threat emerged from a new GM plant, scientists would quickly identify and eliminate it. “We know where the gene goes and can measure the activity of every single gene around it,” Goldberg says. “We can show exactly which changes occur and which don't.” [For more on how GM plants are analyzed for health safety, see “The Risks on the Table,” by Karen Hopkin; Scientific American, April 2001.]
And although it might seem creepy to add virus DNA to a plant, doing so is, in fact, no big deal, proponents say. Viruses have been inserting their DNA into the genomes of crops, as well as humans and all other organisms, for millions of years. They often deliver the genes of other species while they are at it, which is why our own genome is loaded with genetic sequences that originated in viruses and nonhuman species. “When GM critics say that genes don't cross the species barrier in nature, that's just simple ignorance,” says Alan McHughen, a plant molecular geneticist at U.C. Riverside. Pea aphids contain fungi genes. Triticale is a century-plus-old hybrid of wheat and rye found in some flours and breakfast cereals. Wheat itself, for that matter, is a cross-species hybrid. “Mother Nature does it all the time, and so do conventional plant breeders,” McHughen says.
Could eating plants with altered genes allow new DNA to work its way into our own? It is theoretically possible but hugely improbable. Scientists have never found genetic material that could survive a trip through the human gut and make it into cells. Besides, we are routinely exposed to—we even consume—the viruses and bacteria whose genes end up in GM foods. The bacterium B. thuringiensis, for example, which produces proteins fatal to insects, is sometimes enlisted as a natural pesticide in organic farming. “We've been eating this stuff for thousands of years,” Goldberg says.
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The difference is that selective breeding or mutagenic techniques tend to result in large swaths of genes being swapped or altered. GM technology, in contrast, enables scientists to insert into a plant's genome a single gene (or a few of them) from another species of plant or even from a bacterium, virus or animal. Supporters argue that this precision makes the technology much less likely to produce surprises. Most plant molecular biologists also say that in the highly unlikely case that an unexpected health threat emerged from a new GM plant, scientists would quickly identify and eliminate it. “We know where the gene goes and can measure the activity of every single gene around it,” Goldberg says. “We can show exactly which changes occur and which don't.” [For more on how GM plants are analyzed for health safety, see “The Risks on the Table,” by Karen Hopkin; Scientific American, April 2001.]
And although it might seem creepy to add virus DNA to a plant, doing so is, in fact, no big deal, proponents say. Viruses have been inserting their DNA into the genomes of crops, as well as humans and all other organisms, for millions of years. They often deliver the genes of other species while they are at it, which is why our own genome is loaded with genetic sequences that originated in viruses and nonhuman species. “When GM critics say that genes don't cross the species barrier in nature, that's just simple ignorance,” says Alan McHughen, a plant molecular geneticist at U.C. Riverside. Pea aphids contain fungi genes. Triticale is a century-plus-old hybrid of wheat and rye found in some flours and breakfast cereals. Wheat itself, for that matter, is a cross-species hybrid. “Mother Nature does it all the time, and so do conventional plant breeders,” McHughen says.
Could eating plants with altered genes allow new DNA to work its way into our own? It is theoretically possible but hugely improbable. Scientists have never found genetic material that could survive a trip through the human gut and make it into cells. Besides, we are routinely exposed to—we even consume—the viruses and bacteria whose genes end up in GM foods. The bacterium B. thuringiensis, for example, which produces proteins fatal to insects, is sometimes enlisted as a natural pesticide in organic farming. “We've been eating this stuff for thousands of years,” Goldberg says.
- More Here
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