This is not my field so I will leave the explanations to others, but these systems that can be ordered from a laboratory supply house have proved to be effective and reliable tools for tightly targeted genome engineering by cutting out or activating existing DNA. The CRISPR/Cas9 system has been hailed as a game changer for its simplicity to use and have proved to be an effective and reliable tools for genome engineering. However, the CRISPR technology is mired in intellectual property disputes. Ownership of TALENs is clearly defined and reportedly TALENs is can be better at hitting an exact location in the genome and making clean cuts in DNA. One of the co-inventors of TALENs is developing and extensive set of CRISPR tools for facilitating its use in plant laboratories.
In the United States these tools are being widely used to modify plants and crops to improve yield, make plant more drought resistant, blight and disease resistant, improved shelf life of produce, even produce soybeans with reduced trans fats in the oil. Surprisingly, the U.S. Department of Agriculture (USDA) has so far exempted plants altered by TALENS and CRISPER from being classified as “Genetically Modified, (GM).” The USDA’s existing rules on genetic modification focus on whether a plant contain “foreign” DNA from a plant pest or pathogen. These regulations were developed two decades ago when “gene guns” were used to insert new genes into plants. So far, the USDA has ruled that crops in which TALENs and CRISPR gene editing has eliminated DNA bases are not GM. No decision has yet been made on crops where TALENs and CRISPR methods have been used to introduce, replace or add genes.
Older techniques were crude, they relied on injecting a gene for a desired trait and hoping it would land at a spot on the genome where it could be active. Developing, testing and getting regulatory approval for a plant modified in this way could take decades and cost up to $100 million. This limited the development of genetically modified plants to large companies and commodity crops. The USDA exemptions for TALENs and CRISPR edited plants allows small companies to develop food products from gene edited plants.
The European Union has postponed its decision on whether or not to label TALENS and CRISPR edited plants as Genetically Modified or not. Canada labels all plants that have had a novel trait introduced by any method. The USDA has focused their rules on whether a plant contains “foreign” DNA. Scientists who favor plant modification argue that TALENs and CRISPR are merely a faster way to “bred” a desirable trait in a plant. They see the USDA standard is appropriate since TALENs and CRISPR leave no DNA behind so that the resulting plant should be indistinguishable from plants that with enough time could be naturally bred. However, is it honest to not label these plants, crops and the resulting food products as resulting from modified plants; or is the fact that mankind has been modifying plants using selective breeding for thousands of years make labeling moot? You decide.
DuPont (a company I once worked for) is a leader in the CRISPR area, with about 60 patents and applications and more than 30 published scientific articles. The company uses CRISPR in at least two distinct ways:
- DuPont Nutrition & Health uses the native CRISPR-Cas system to select, through what they describe as “a fully natural process,” bacteria that are immunized against bacteriophages. The natural immunization process does not involve gene editing technologies. The use of starter cultures containing such immunized bacteria ultimately improves the quality and safety of fermented dairy foods.
- DuPont Pioneer utilizes CRISPR-derived tools for genome editing applications. The genome editing technology is capable of making exact changes to the DNA of many organisms. In plants, this editing capability can be applied to promote drought tolerance and disease resistance to protect plant health and increase crop yields. It also can eliminate food allergens and improve the nutrient composition of plant-derived oils.DuPont Pioneer plans a CRISPR altered version of its “waxy corn” that was deemed by the USDA to not be “genetically modified.”