For the last decade, CRISPR-Cas9 has enabled plant breeders and scientists to develop improved varieties of common crops in an easier, faster, and more cost-effective way. Refining genetic properties and improving genetic traits such as yield and disease tolerance allows a dwindling number of farmers to feed a growing global population. While there are no GMO wheat varieties grown commercially in the United States, using CRISPR technology, scientists have been able to successfully produce wheat varieties that are resistant to herbicides and drought, produce higher yields on dryland farms, and reduce lodging when grown under irrigation.
What is the difference between CRISPR and traditional breeding?
There are four primary technologies used to improve crops. Zinc Finger Nuclease (ZFN) is the oldest, developed in the 1990s. While effective, ZFN-based improvements take a very long time to produce results, are laborious, and have the highest rate of producing unintentional results.
Transcription Activator-like Effector Nucleases (TALENS), developed in 2009, has a similar engineering structure and function to ZFN but is more accurate and more affordable than its ancestor. Like ZFN, TALENS is very time-consuming and frequently produces off-target results.
RNA Interference (RNAi) works by attacking messenger RNA carrying instructions for the targeted genetic trait and turns the trait on or off. RNAi has been used in Simplot potatoes and to develop insect- and disease-resistant crops. RNAi is also the technique Bayer is using for a spray to combat weeds that have developed resistance to glyphosate, which neutralizes the resistance in those weeds.
CRISPR is much more affordable, accurate, and faster than ZFN or TALENS, which makes it attractive for agricultural applications. CRISPR shaves years from the process of methodically crossing generations of plant species to eventually get the desired trait.
Using a natural “molecular scissor” technique, Cas9, scientists cut a section of DNA and either reconnect the loose DNA ends together, eliminating the undesired trait, or insert DNA with a desirable trait into the cut strand. CRISPR-Cas9 is so precise that scientists can cut any DNA at any predetermined location. For example, the DNA trait that determines the height of wheat can be eliminated and replaced with DNA that keeps a specific wheat variety short enough to mature under wheel lines.
Today, hundreds of researchers and development labs are testing CRISPR to solve food-related concerns for growers and consumers, including reduced-gluten wheat that could be tolerated by those with sensitivities and intolerances. Because CRISPR crops do not contain foreign DNA – DNA from viruses or bacteria – the United States Department of Agriculture (USDA) and the Food and Drug Administration (FDA) do not classify CRISPR crops as genetically-modified organisms, or GMO.
GRAPHICS: NATIONAL GEOGRAPHIC
SOURCES: BRITANNICA.COM/SCIENCE/GENE-EDITING; GENETICLITERACYPROJECT.ORG/GMO-FAQ/WHAT-ARE-CRISPR-AND-OTHER-NEW-BREEDING-TECHNIQUES-NBTS/; NATIONALGEOGRAPHIC.COM/ENVIRONMENT/ARTICLE/FOOD-TECHNOLOGY-GENE-EDITING
