‘Snip, edit, grow’ with gene editing techniques for improving food security

KAUST researchers—including those from Associate Professor Magdy Mahfouz's research group—work to improve gene editing tools for crop bioengineering. File photo.

By Sonia Turosienski, KAUST News

The Earth's increasing population and changing climate pose major threats to food security. Experts estimate that the world's population will reach 9.7 billion by 2050, with higher temperatures and changes in rainfall adversely affecting crop yields in many regions.

Countering this threat will require plant researchers and crop breeders to increase yield—that is, the amount of food a plant can produce. However, they must also decrease losses by making crops more resistant to disease and changing environmental factors. One of the most promising solutions to this dual challenge is genome engineering via gene editing, which allows targeted improvement of the key genes regulating the factors that contribute to yield and stress tolerance.

Researchers examine plant specimens in one of the University's greenhouse facilities. File photo.

Over the past several decades, gene editing techniques such as CRISPR/Cas9 have made waves in research and public policy. These cutting-edge techniques benefit from ongoing innovation and emerging discoveries that have improved their specificities and expanded their utility from simple genomic modifications to the editing of RNA, transcriptional regulation and even engineering virus resistance.

KAUST Associate Professor Magdy Mahfouz and his research team from his Genome Engineering Lab are pictured here on the University's campus. File photo.

Magdy Mahfouz, KAUST associate professor of plant science and head of the Genome Engineering Lab, part of the University's Center for Desert Agriculture, and his research team are working to improve the specificity, delivery and usage of existing gene editing tools for crop bioengineering. Mahfouz's group also develops new and innovative methods, including engineering virus resistance and using germline engineering to produce crops with improved agricultural traits such as heat tolerance, salt stress and resistance to disease.

Sharpening the molecular scissors

CRISPR/Cas9 gene editing uses the Cas9 protein as "molecular scissors" to cut the DNA at a specific site. This break in the double-stranded DNA may disable a gene, create a new mutation once it is repaired or provide a place for a new gene to be inserted.

A KAUST researcher works in Associate Professor Magdy Mahfouz's Genome Engineering Lab on campus. Photo by Sarah Munshi.

Cas9 is directed to its specific site by a guide RNA; researchers can easily specify this guide RNA sequence, thus targeting Cas9 to any region of the genome. The CRISPR system revolutionized and democratized gene editing research by doing away with the need for complex protein engineering, increasing speed and precision and reducing cost.

KAUST Associate Professor Magdy Mahfouz believes the applications of gene editing may help reshape the future of agriculture. Image courtesy of Shutterstock.

In a test tissue, such as a leaf or root, CRISPR/Cas9 editing occurs in individual cells. One challenge is to generate a complete plant from a single edited cell—this can be readily done for some crops, but it requires a lengthy plant tissue culture process. Moreover, sometimes producing Cas9 in cells requires the addition of foreign DNA.

To facilitate the generation of gene-edited plants that do not contain foreign DNA, Mahfouz and his lab are working on a new germline engineering platform that targets a specific cell and does away with the time-consuming tissue culture process.

KAUST Associate Professor Magdy Mahfouz's research group works on germline engineering to produce gene-edited plants without foreign DNA. Image courtesy of Shutterstock.

"Ideally, you want a crop that carries no foreign DNA. With germline engineering, you deliver the upgraded proteins straight to the cell without the need to add foreign DNA," Mahfouz explained. "The protein makes the edit and then decays. Editing can be achieved with the traditional CRISPR approach too, but it takes several generations to regenerate an edited plant and segregate out the foreign DNA. We think germline engineering has the potential to save a lot of time, money and effort."

Magdy Mahfouz, KAUST associate professor of plant science, believes 'germline engineering [for plants] has the potential to save a lot of time, money and effort,' he stated. File photo.

The GMO controversy

recent decision from the European Court of Justice ruled that crops created using CRISPR/Cas9 would be classed as genetically modified organisms (GMO) and be subject to stringent regulations in Europe. However, the research community has challenged this decision.

Genetically modified organisms—including crops produced from bioengineered plants—have caused controversy worldwide. Image courtesy of Shutterstock.

"CRISPR-edited crops should not be classed as GMOs because they do not have a transgene from another organism. Edited plants only have some small changes in their genes, similar to changes that occur naturally. If you take two plants from a field, for example, no two plants will have exactly the same DNA sequence," Mahfouz said.

While Europe has taken a more conservative approach, in the U.S., CRISPR-edited mushrooms are already in the market.

In the United States, mushrooms produced by the gene editing technique CRISPR are already sold in supermarkets. Image courtesy of Shutterstock.

"The applications [of gene editing] are almost unlimited. I think these tools will reshape the future of agriculture and the future of gene therapy," Mahfouz noted. "More than 20 to 30 percent of genetic diseases are caused by mutations—so just being able to treat these alone will have a huge impact.

"There are ethical issues to consider, of course...but the big difference in agricultural applications is that the gene editing machinery is precise and can be separated out, so the resulting crop has no foreign DNA and is indistinguishable from conventional varieties."

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