Biotechnology

Mr. Green Genes

An old anti-biotech activist tries to engineer some confusion.

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Long time anti-biotech activist Jeremy Rifkin has come out in favor of a biotechnology technique. Should beleaguered biotechnologists break out the champagne and start celebrating? Not hardly. Earlier this week, Rifkin wrote an op/ed in the Washington Post in which he declared his support for marker assisted selection (MAS) for use in plant breeding. So far, so good.

MAS is a molecular technique in which researchers identify sections of DNA in a plant or animal located near a gene or genes that confer specific valuable traits. In plants, such traits might increase their resistance to drought or disease, or they might boost their productivity. Once a trait has been identified, researchers can trace it as they crossbreed the plants containing it with commercial varieties. Thus MAS makes it far easier for plant breeders to identify which of the crossbred plants carry the trait. That means that breeders don't have to plant the seedlings and then wait for them to grow up in the field before identifying which ones carry the sought-after new trait. MAS can cut the time to develop new commercial crop varieties in half.

Rifkin points to all of these advantages, but then declares that MAS has "made gene splicing and transgenic crops obsolete and a serious impediment to scientific progress." Whoa. Could that be true?

Plant geneticists and breeders don't agree. According to Alan McHughen, a plant biotechnologist at the University of California, Riverside, "The problem for Rifkin: MAS is not, as he suggests, an alternative to gene splicing (recombinant DNA or rDNA), but an adjunct. Both are powerful and useful tools that can be used together."

McHughen offers a real life example of how MAS and gene-splicing have been used to introduce disease resistance in rice. Many rice varieties have regularly been devastated by bacterial leaf blight. Fortunately, back in the 1970s researchers identified a blight-resistant species of wild rice native to Mali. Given the state of biotech then, it took years for the Xa21 gene that confers blight resistance to be identified. By the late 1990s, some California plant biotechnologists succeeded in using gene-splicing to insert the Xa21gene into commercial rice varieties to endow them with blight resistance. In 2003, Chinese plant breeders reported using MAS to identify and guide their efforts to successfully crossbreed a blight resistant rice variety with a productive commercial variety. Both are resistant to blight, but Rifkin wants to claim that one is a danger and the other is safe. Rifkin asserts that "With MAS, the breeding of new varieties always remain within a species, thus greatly reducing the risk of environmental harm and potential adverse health effects associated with genetically modified crops."

However, as McHughen points out, "The irony—if not stupidity—is that the resulting plant in each case is genetically identical. If one plant is safe, the other is equally safe. If one carries risks, the other carries the identical risks. Yet to Rifkin, the GE (genetically engineered) rice is so hazardous that it demands banning outright, and the other rice is the savior of sustainable agriculture." And what if the genes for disease resistance had not been found in a wild variety of rice, but in corn? Should farmers forego that advantage just because Mother Nature hadn't figured out a way to get beneficial genes from one species to another before human gene splicers came along?

Evidently, Rifkin thinks that breeding "within a species" is safe, but inserting genes from outside species is inherently bad, perhaps even immoral. Back in 1998 when he was flogging his book, The Biotech Century: Harnessing the Gene and Remaking the World, Rifkin warned that because of biotech, "All living beings are drained of their substance and life becomes a code to be deciphered. There is no longer any question of sacredness or specialness."

Of course, not all of us share Rifkin view that tomatoes, soybeans and rice are inviolable entities, so he hints at environmental risks and adverse health effects to get people's attention. However, Rifkin doesn't cite examples of any such dangers. He can't; there haven't been any. In 2004, the National Academy of Sciences issued a comprehensive report with the fetching title, Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects that concluded, "To date, no adverse health effects attributed to genetic engineering have been documented in the human population." The NAS also found that "assess[ing] products based exclusively on their method of breeding is scientifically unjustified." In other words, there is no reason to assess food made from genetically engineered crops any differently than foods made from traditional breeding methods. The NAS did recommend additional scrutiny if specific genetic modifications significantly change the nutritional composition of a food crop. Speaking of health risks, toxic varieties of crops have been produced by means of conventional breeding, as happened in the case of an insect resistant variety of celery (produced too much psoralen) and a potato (too much solanine).

So what about the potential environmental "risks" hinted at by Rifkin? He shares one frequently expressed concern by many opponents of genetically engineering crops that transgenes (the inserted genes) will "contaminate" conventional varieties or wild relatives through crossbreeding. As support, Rifkin cites a Union of Concerned Scientists survey that claimed that traditional varieties of corn, soybeans and canola are "pervasively contaminated with low levels of DNA sequences originating in genetically engineered varieties of these crops." Rifkin adds, "Cleaning up contaminated genetic programs could prove to be as troublesome and expensive in the future as cleaning up the viruses that invade software programs."

Rifkin fails to explain why something like the Xa21 gene is a "contaminant" if it derives from crossbreeding with a gene-spliced variety, but is not a contaminant if it comes from crossbreeding with an MAS variety. "No geneticist uses the term 'contamination'- it is a purely non-scientific construction designed to elicit an emotional response from non-scientists," says McHughen. "DNA is not a virus and bears no analogous relationship to computer viruses, except, perhaps, by those who wish to trick people into adopting an otherwise unpalatable political agenda."

Ultimately, Rifkin's latest proposal creates a false dichotomy, genetic engineering or MAS, when, in reality, it is both. McHughen concludes, "Rifkin is an opportunistic parasite, preying on people's scientific ignorance to generate funding and support."