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How tweaking genes keeps corn and rice on your plate

photo of rice grains and rice ear
Image: © yaibuabann – stock.adobe.com
Can plant scientists keep up with a changing world? It took thousands of years of breeding for farmers to transform the wild ancestors of corn and rice into the staples that we grow and consume on a massive scale. But to keep up with population growth, climate change, and other pressures, those crops will have to change in new ways. Today, we have CRISPR, a powerful gene-editing technology to accelerate this process.

Modern biology can speed crop improvements. Plant geneticists like Cold Spring Harbor Laboratory (CSHL) Professor David Jackson can pinpoint factors that control plants’ health and development, then fine-tune them in a lab to optimize features like productivity, growth efficiency, and climate resilience. The approach is particularly powerful because, as Jackson and colleagues recently demonstrated in a study of both corn and rice, when researchers figure out how to adjust a trait at its genetic source, lessons from one plant may be applied to the improvement of another.

What’s good for one plant may be good for another

Much of the work in Jackson’s lab focuses on corn, one of the world’s most abundant crops. The world produced more than one billion metric tonnes of corn in 2019. With genetic adjustments devised by Jackson and his collaborators, yield could rise. Jackson and colleagues in China have found that a gene called KRN2 limits how many rows of kernels a corn cob can produce. Eliminating that gene leads to more kernels, increasing yield by ten percent. It’s one of multiple genetic strategies for increasing productivity.

The corn that feeds the world comes from a wide variety of corn strains. A variety that thrives in the industrial farms of the midwestern United States is unlikely to grow well in a field in Oaxaca, Mexico, where the soil, climate, and pathogens are different—but thanks to corn’s genetic diversity, there’s another that will. “There are thousands of varieties of corn that are grown around the world, and they’re all locally adapted,” Jackson says. But the plants share enough genetics that many of them could respond similarly to the specific modifications that Jackson and his collaborators have found can increase yield. With the quick and efficient gene-editing tool CRISPR, it’s easy to find out.

“The advantage of this kind of CRISPR approach is that you could take a variety from a different country, anywhere, and just knock out this one KRN2 gene and potentially increase its yield,” Jackson says.

Moving beyond corn

Better yet, what works in corn can work in other grains, too. In March, Jackson and his collaborators reported in Science that eliminating KRN2 causes rice plants to produce more branches on their seed-producing inflorescence. That allows more grains to develop, producing a larger harvest. Like corn, rice is diverse, and researchers will need to experiment to find out which varieties can be made more prolific by eliminating KRN2.

photo of a rice paddy with corn field in foreground
Corn plants growing, with rice paddies in the background, in Sapa, Vietnam.

While farmers have taken advantage of plants’ natural diversity to grow foods suited to local conditions and preferences, certain traits are essential for agriculture. As wild plants were domesticated, growers favored those that could be grown and harvested reliably. When selecting for critical traits, breeders coaxed certain genetic similarities out of the plants we now rely on for food. Those similarities could make it easier for researchers to introduce improvements that are successful in one crop, like corn, into an entirely new plant.

“I talk to a lot of people in companies—they want to use CRISPR to improve crops,” Jackson says. “And their first question for me is, what should I target? Which gene should I pick and which is going to be the one that’s going to improve the yield? That’s been a major sticking point, knowing how to apply the technology—which genes to tweak.”

In their recent work with corn and rice, Jackson’s collaborators identified nearly 500 genes that, like KRN2, have been selected by breeders in both plants. That could help scientists take advantage of what’s known about corn to identify targets for gene editing to potentially improve rice plants. Meanwhile, Jackson’s lab is looking for regions outside of genes, in regulatory parts of the genome, that are shared between different species of plants. With CRISPR, Jackson says, it will be easy to test both kinds of targets to find ways to improve crops’ agronomic traits. “I think CRISPR is going to have a huge impact on agriculture,” he says, “and not only on yield, but hopefully in making agriculture more sustainable.”

 

Editor’s note

David Jackson’s work in corn carries on a long tradition of maize genetics research at Cold Spring Harbor Laboratory that began with George Shull in the early 1900s and continued mid-century with Nobelist Barbara McClintock. Plus, it gives him the opportunity to get outside, working in the fields in the summertime. Jackson is also a visiting professor at Huazhong Agricultural University in Wuhan, China. He travels frequently to China to collaborate with colleagues in Wuhan and Beijing.

Written by: Jennifer Michalowski, Science Writer | publicaffairs@cshl.edu | 516-367-8455

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