By Samantha Stadmiller
CRISPR-Cas9 technology is a genome-editing technique that has the capability to affect a variety of fields from healthcare and biomedicine to crops and agriculture. But what exactly is it? Why is it better than the other techniques for genetic engineering? How can it change the future of agriculture? And what concerns should we have moving forward?
Although the CRISPR-Cas9 technology is simplistic and elegant, the concept of genetic engineering and genetic-editing is not brand new. In agriculture, humans have been selecting for favorable crop traits through a variety of methods for centuries. Some commonly used ways to select for certain traits include conventional breeding, mutagenesis, and genetic modification. Conventional breeding has been practiced for thousands of years and is simply the selection of plants with better traits. Farmers often save the seeds of these plants for future years to create crops with desirable traits. Mutagenesis with chemicals and radiation involves randomly mutating plants, breeding them, and selecting for superior traits. Finally, genetic modification involves incorporating new DNA into a plant that can be from a related or non-related organism. The CRISPR-Cas9 gene-editing system is different from these methods in that it is able to specifically change, insert, or remove portions of the plant’s own DNA in a very specific way.
So what makes CRISPR such a special gene-editing technique and why does it have such widespread applications? It comes down to its simplicity, cost-effectiveness, and highly specific ability to edit only the portion of DNA that you wish to change. Although the uses of CRISPR are seemingly limitless, the motivation for studying these clustered regularly interspaced short palindromic repeats (CRISPRs) of DNA was to understand bacterial immunity.
When most people talk about CRISPR, they are referring to the CRISPR-Cas9 system, which is able to protect bacteria from infection from things like viruses. Most simply, it is the bacterial immune system. So the discovery of this extremely elegant genetic editing system came from scientists trying to understand how a single cell is able to protect itself from harmful pathogens in its environment. The virus DNA, along with another molecule similar to DNA called RNA, are able to guide the Cas9 protein towards the infectious DNA of the pathogen. The Cas9 protein then works as a molecular scissor to only cut up the foreign DNA and protect the bacteria from its invader. The high specificity of the Cas9 protein to only cut up the invader DNA makes it a versatile gene-editing technique and adaptable to nearly any DNA sequence of our choosing.
With nearly endless applications, one of the most important uses of this new technology according to Jennifer Doudna, one of the scientists to first publish on the CRISPR-Cas9 system and one of the leaders in the “CRISPR revolution”, is for agriculture and crop production. CRISPR, some claim, can even end the world hunger crisis.
It is expected that the global population will increase by 60-100% by 2050; therefore, our food production must increase. The rapidly increasing population along with the increase in extreme weather, reduced land availability, and agricultural pests are barriers that must be overcome to keep up with the food demand. CRISPR has the ability to improve our crop production. Editing the genomes of plants can be used to increase yield, enhance pest resistance, extend shelf-life, and even improve nutritional content.
Although the CRISPR-Cas9 system is a fairly new gene-editing technology, we may see its effects as early as this year, with gene-edited canola planning to hit the US market in 2019. And the possibilities are endless. Scientists at DuPont have been working since 2016 on using CRISPR-Cas9 to make drought-resistant corn. Other staples are also being modified. Rice is being gene-edited to increase yield and they are working on making wheat with a lower gluten content for accommodating those with celiac disease. Experiments are also being conducted on mushrooms to increase shelf-life and tomatoes to create new flavors and varieties. Scientists’ knowledge of the link between a plant gene and its displayed trait allows CRISPR to be used to very specifically modify and edit the plant DNA.
CRISPR-Cas9 has the ability to improve the agricultural field in a multitude of ways, but new technology always comes with consequences that scientists and the general public should be aware of. One common challenge with using CRISPR-Cas9 is the introduction of mutations, DNA insertions, or DNA deletions other than those intended. In plants, this means it could alter traits that were not intended to be changed. The European Union has already planned for this and is subjecting CRISPR modified plants to stringent laws. In addition to passing new laws regulating its use, conversations between scientists, journalists, ethicists, and the public must be generated. There is still much skepticism in the public about gene-editing and we all must actively work to create open lines of communication about the science of CRISPR, its benefits, and its consequences.
What once started as scientists’ curiosity to understand the fundamental science and biochemistry underlying the bacterial immune system has turned into a worldwide revolution with immense applications for improving nearly all aspects of our lives. Although there still remains much research and conversation to be had on the subject, including its regulation, it is one of the most important scientific discoveries with the ability to change the future of our food.
Want to read more on CRISPR, its discovery, and implications for society? Check out A Crack in Creation written from Jennifer Doudna’s perspective.
Peer-reviewed by Leah Chapman