How CRISPR is Changing What We Eat
Quick Summary
- Given the exponentially rising global population, agriculture is under increasing pressure to meet human needs.
- Gene-editing tools like CRISPR and Cas systems have altered how we approach these problems, by changing how food is grown on a warming, crowded planet.
- CRISPR has moved agricultural biotechnology from a slow area of study into a rapidly growing field.
Given the exponentially rising global population, agriculture is under increasing pressure to meet human needs. With the world estimated to reach 9.7 billion people by 2050, food production must increase by roughly 25–70%. This challenge is compounded by obstacles in plant breeding which include water scarcity, pest pressure, climate change, and limited arable land. Gene-editing tools like CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) and Cas systems have altered how we approach these problems, by changing how food is grown on a warming, crowded planet.
CRISPR-Cas9 works by forming an RNA-DNA hybrid in which a guide RNA directs the Cas9 protein to a precise genomic location, where it introduces a double-strand break. The cell's own repair machinery then takes over through either non-homologous end joining (NHEJ) or homology-directed repair (HDR), which can disable a gene, correct a mutation, or enable the insertion of a new sequence. For a deeper look at the basic mechanism, BIG's earlier post, CRISPR and the Future of Biotech, which covers the fundamentals well. In plants, delivery of the CRISPR machinery poses an added challenge, because Cas9 is a large protein, transporting it through plant cell walls is difficult. Recent methods, including nanoparticle-mediated delivery and ribonucleoprotein (RNP) complex delivery, have improved efficiency in crops like wheat and maize, expanding gene edits potential.
One of CRISPR's most important contributions to agriculture is helping crops survive the pathogens that devastate crop yields worldwide. Researchers at UC Davis and Huazhong Agricultural University used CRISPR-Cas9 to edit the newly discovered RBL1 gene in rice (Oryza sativa), producing plants resistant to rice blast fungus (Magnaporthe oryzae), one of the most destructive plant diseases on Earth. In field trials conducted in disease-heavy regions, the edited rice produced five times the yield of control plants. Similar studies are working on citrus crops threatened by bacterial greening disease, and on cacao, which faces possible extinction from the fungal pathogen Phytophthora tropicalis.
Beyond disease resistance, CRISPR can also improve what crops deliver nutritionally. UC Davis scientists engineered rice with elevated levels of beta-carotene, (a compound related to vitamin A) by inserting the relevant gene into specific chromosomal regions. Scientists have also used CRISPR to knock out the gene responsible for browning in mushrooms and apples, which is helpful for reducing food waste.
Another question that comes up is whether this is simply another form of GMO. The distinction matters both scientifically and legally. Traditional GMO technology transfers genes from one species into another, while CRISPR, in most agricultural settings, works within the organism's own genome, by editing what is already there rather than adding something foreign. In the United States, CRISPR-edited crops that contain no foreign DNA may not fall under USDA GMO regulation, which reduces the time between lab and field.
CRISPR has moved agricultural biotechnology from a slow area of study into a rapidly growing field. Disease-resistant crops, drought-tolerant varieties, and nutritionally advanced foods are already in field trials, with some working towards regulatory approval. Many of the more exciting applications still lie ahead. For example, researchers are exploring gene edits that help wheat grow deeper roots for drought resilience, and UC Davis scientists are investigating how editing can help dairy cattle better withstand rising heat. The tools being refined in these studies are the same ones that will define what agricultural biotechnology looks like for the next generation of researchers. Given the scale of the problems they are designed to address, the next generation has no shortage of future meaningful work.
Sources:
https://www.nature.com/articles/s41467-020-14981-y
https://www.nature.com/articles/nrm.2018.2
https://www.mdpi.com/2673-8392/2/1/36
https://www.annualreviews.org/content/journals/10.1146/annurev-arplant-050718-100049
https://www.nature.com/articles/s41580-020-00288-9