Scientists Used Gene Editing to Make Super Corn
Reengineering Life is a column from Future Human about the ways humans are using biology to reprogram our bodies and the world around us.
Thanks to selective breeding over the course of some 9,000 years, humans were able to transform an ancient wild grass with dinky cobs and a handful of kernels into the sweet, juicy corn we know today.
More recently, scientists have used genetic engineering to further transform the crop, resulting in pest-resistant corn. Now, researchers think gene editing — which is far more precise than traditional genetic engineering — could improve corn even more. In a recent study published in Nature Plants, researchers used gene editing to increase the number of kernels on ears of corn.
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The researchers think the strategy could lead to more sustainable crops, which would be a boon for the United States, where more than 90 million acres of land are used for corn. Around a third of all the corn produced is used for livestock feed, while another third is used to make ethanol, a renewable fuel added to gasoline. The rest of the country’s corn is harvested for human consumption or industrial uses or is exported elsewhere.
To make their super corn, researchers at Cold Spring Harbor Laboratory in New York and the University of Massachusetts used the gene-editing technique CRISPR to tinker with corn kernel numbers. They targeted a group of genes in the maize genome involved in the promotion of stem cell growth. Like in humans, stem cells provide plants with a source of new cells to regenerate damaged or diseased tissue.
“Farmers are going to be using fewer resources — less land, less fertilizer, less water, and less time to get more kernels.”
By tweaking one of these genes, ZmCLE7, which acts like a brake to stop stem cell growth, the researchers were able to control the number of kernels the resulting corn produced. CRISPR is known for its ability to bind to and delete genes, but rather than remove the gene entirely, researchers used a modified version of CRISPR to change how pronounced its effects are on the corn’s appearance.
“If you knock out a gene completely, then you often have a very strong effect,” study author David Jackson, PhD, a plant scientist at Cold Spring Harbor Laboratory, tells Future Human. “For many genes, that will severely reduce yield.”
Decreasing the gene’s activity — essentially, letting off the brake — led to an increase in the number of kernels the corn produced. Increasing the gene’s activity, meanwhile, had the effect of stomping on the brake harder—it reduced the number of kernels. Editing out the gene entirely shortened the cob, disrupted the kernel’s row patterns, and resulted in fewer kernels.
The result was “nothing that anyone would want everyone to eat or grow,” Jackson says.
Corn production isn’t very sustainable. It drains nutrients from soil, and growing it uses a lot of water and fertilizer. But Jackson and his co-authors think gene editing could make corn a more sustainable crop.
“More kernels per ear means higher yield,” Madelaine Bartlett, associate professor of plant biology at the University of Massachusetts Amherst, tells Future Human. One corn plant produces only two to four ears of corn. But if that ear can make more seeds, or kernels, then each plant would make more corn.
“That means farmers are going to be using fewer resources — less land, less fertilizer, less water, and less time to get more kernels,” Bartlett says.
Bartlett and Jackson don’t want to oversell the results of their work. The corn varieties that he and his collaborators work with for research purposes are different from the agricultural varieties that are grown for our food supply. They think the approach will translate, but they’re not sure. Jackson hopes an agriculture company will pick up where his group left off and try similar experiments in types of corn that farmers grow.
There are also many factors — genetic and otherwise — that affect crop yield. The researchers are interested in tinkering with other genes to see what gene edits might be combined to get the plumpest, highest-yielding corn.
Getting gene-edited crops to our plates will not be an easy task. Scientists will have to overcome the public’s distrust of GMOs, which in some cases is warranted. While the safety of GMOs is clear, the benefits of these crops are less so. For instance, Bt corn and cotton, which were engineered to resist pests, are losing their ability to do so.
Scientists think the distinction between traditional genetic engineering and gene editing could help win over skeptics. Whereas classic genetic engineering involves taking genetic material from one plant species and putting it into another species, gene editing uses no foreign DNA; instead, it tweaks a plant’s own DNA.
“These edits that you can make with CRISPR genome editing are the same changes that could have happened during domestication and crop improvements,” Bartlett argues. “But now we don’t have to wait for these changes to happen by chance.”
As the planet faces climate change, land degradation, and an ever-increasing human population, Bartlett thinks gene editing could accelerate crop improvements to help ensure food security.