Moving beyond pro-con debates over genetically engineered crops

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Since the 1980s biologists have used genetic engineering to express novel traits in crop plants. Over the last 20 years, these crops have been grown on more than one billion acres in the United States and globally. Despite their rapid adoption by farmers, genetically engineered (GE) crops remain controversial among many consumers, who have sometimes found it hard to obtain accurate information.

Last month the U.S. National Academies of Sciences, Engineering, and Medicine released a review of 20 years of data regarding GE crops. The report largely confirms findings from previous National Academies reports and reviews produced by other major scientific organizations around the world, including the World Health Organization and the European Commission.

I direct a laboratory that studies rice, a staple food crop for half the world’s people. Researchers in my lab are identifying genes that control tolerance to environmental stress and resistance to disease. We use genetic engineering and other genetic methods to understand gene function.

I strongly agree with the NAS report that each crop, whether bred conventionally or developed through genetic engineering, should be evaluated on a case-by-case basis. Every crop is different, each trait is different and the needs of each farmer are different too. More progress in crop improvement can be made by using both conventional breeding and genetic engineering than using either approach alone.

Modern cultivated corn was domesticated from teosinte, an ancient grass, over more than 6,000 years through conventional breeding.
Nicole Rager Fuller, National Science Foundation
Convergence between biotech and conventional breeding

New molecular tools are blurring the distinction between genetic improvements made with conventional breeding and those made with modern genetic methods. One example is marker assisted breeding, in which geneticists identify genes or chromosomal regions associated with traits desired by farmers and/or consumers. Researchers then look for particular markers (patterns) in a plant’s DNA that are associated with these genes. Using these genetic markers, they can efficiently identify plants carrying the desired genetic fingerprints and eliminate plants with undesirable genetics.

Ten years ago my collaborators and I isolated a gene, called Sub1, that controls tolerance to flooding. Million of rice farmers in South and Southeast Asia grow rice in flood prone regions, so this trait is extremely valuable. Most varieties of rice will die after three days of complete submergence but plants with the Sub1 gene can withstand two weeks of complete submergence. Last year, nearly five million farmers grew Sub1 rice varieties developed by my collaborators at the International Rice Research Institute using marker assisted breeding.

In another example, researchers identified genetic variants that are associated with hornlessness (referred to as “polled”) in cattle – a trait that is common in beef breeds but rare in dairy breeds. Farmers routinely dehorn dairy cattle to protect their handlers and prevent the animals from harming each other. Because this process is painful and frightening for the animals, veterinary experts have called for research into alternative options.

In a study published last month, scientists used genome editing and reproductive cloning to produce dairy cows that carried a naturally occurring mutation for hornlessness. This approach has the potential to improve the welfare of millions of cattle each year.

Reducing chemical insecticides and enhancing yield

In assessing how GE crops affect crop productivity, human health and the environment, the NAS study primarily focused on two traits that have been engineered into plants: resistance to insect pests and tolerance of herbicides.

The study found that farmers who planted crops engineered to contain the insect-resistant trait – based on genes from the bacterium Bacillus thuringiensis, or Bt – generally experienced fewer losses and applied fewer chemical insecticide sprays than farmers who planted non-Bt varieties. It also concluded that farms where Bt crops were planted had more insect biodiversity than farms where growers used broad-spectrum insecticides on conventional crops.