Sci-Tech - Veggie tales
Food progress grows controversy
Published: Wednesday, April 20, 2005
Updated: Wednesday, July 25, 2012 22:07
According to Christopher Leaver, department head of plant sciences at the University of Oxford, this nightmare is indicative of challenges facing proponents of genetically modified crops.
On April 5, Leaver presented a lecture entitled "Plant Biotechnology - GM Crops in Context" as the final lecture of the 2004-05 season of the Texas A&M University Distinguished Lecture Series.
In exploring the scientific, social and political issues surrounding GM crops, Leaver described what will have to be a multifaceted approach for addressing the impending agricultural challenges.
"Today, we could feed everyone on this planet thanks to plant breeding, modern agriculture, the agrichemical industry and so on," Leaver said. "At the present time, making sure everyone has enough to eat is more about politics than science."
This will not always be the case. Leaver said demand will grow as the human population increases from six billion to an expected nine billion by 2050. Without major changes, supply could decrease because current agricultural practices are unsustainable due to their destructive environmental impact.
"We have to develop sustainable and environmentally friendly agriculture, which combines the best of conventional plant breeding, which has been very successful, with the newer biotechnologies," Leaver said.
GM crops will play a central role in this strategy.
All living things have a unique DNA sequence, divided into individual genes. Each gene codes for a particular protein, and the form of that protein contributes to a particular trait in the individual. This code-reading machinery follows the same rules in virtually all life forms, so a specific gene will produce the same protein in plants, as in bacteria.
In the early 1980s, scientists began directly altering the genetic code of plants installing advantageous traits.
In his lecture, Leaver offered a wide range of possibilities for genetic modification, including increasing crop yield, improving nutritional value, providing resistance to disease and even addressing the impending decline in fossil fuel production.
Keerti Rathore, associate professor of soil and crop sciences at A&M, said that despite the possibilities, only two types of GM crops are widely grown: those resistant to herbicides and those that produce insecticides.
Leaver discussed examples of each of these in his lecture. Roundup Ready crops are resistant to the herbicide Roundup, due to a bacterial protein that is highly resistant to glyphosate, its active ingredient. Bt-protected crops are resistant to insects because of a bacterial protein that acts as a natural insecticide.
Leaver also discussed Golden Rice, which is rice modified to produce the vitamin A precursor beta-carotene. He said that vitamin A deficiency, which can lead to blindness, affects about 7 percent of the world's population. Because rice is the primary food source for most of the affected people, scientists five years ago introduced a daffodil gene into rice, leading to production of beta-carotene.
Although it originally showed great promise, Golden Rice has still not been cultivated in part due to low yields of beta-carotene. In March, a group of scientists from the biotechnology company Syngenta reported in "Nature Biotechnology" that they could produce 10 to 20 times the amount of beta-carotene in Golden Rice by using a gene from corn instead of daffodil. Now the only hurdle Golden Rice faces is political resistance to GM crops.
Much of the controversy over GM crops has been focused on the idea that the direct genetic manipulation of a life form is unnatural and dangerous. To refute this idea, Rathore said that direct genetic change is much more precise than traditional crop breeding, which also results in genetic changes.
Leaver stressed this point in his lecture as well.
"(Modern crops) are all the creation of man. They've been bred by selection," Leaver said. "They would not exist without man."
In addition, genetic change is exceedingly common in nature. Scientists even use this constant genetic change to construct evolutionary trees that map the relatedness of various species.
Rathore said that scientists use three different methods to genetically modify a crop. One takes advantage of the natural ability of a type of bacteria called Agrobacterium to transfer part of its DNA into plant cells. When that does not work, scientists use a "gene gun," which shoots microscopic pieces of gold covered in the DNA of interest into plant cells. A third method involves stripping individual plant cells of their protective cell walls and shocking them to force them to take up new DNA. This last method is older and is not used as much anymore.
Rathore focuses his research on improving these general methods, adapting them to specific crops and investigating the functions of various genes.
Although much of the controversy over GM crops has focused on the manipulation of DNA as well as health and environmental issues, Sheri Allen-Wright, coordinator of the Brazos Valley Green Party, said that she is more concerned with the social and economic impact of GM crops.
"(GM crops) lead to dependence if you have to buy seeds from a big corporation," Allen-Wright said. "I don't really have faith in our corporations or in our regulatory agencies to really check it."
Although the Texas Green Party has called for a moratorium on GM crops, its stated reasons are to encourage sustainable agriculture and to move away form large agricultural corporations.
Rathore said that although all GM crops in use are marketed by corporations due to the overwhelming expense required to put them in the market, he notes that their patents will begin running out in the coming decades. At that time, university scientists can use their technology to create crops that can be directly transferred to farmers.