Gene-Edited Tomatoes Grow in Bunches Like Grapes, Making Them Ideal for Urban Farming

Growing food in urban environments could have important implications for sustainability—if we can produce crops that thrive in tight spaces

These gene-edited tomatoes grow in grape-like clusters, rather than on long vines. Lippman lab/CSHL, 2019

Tomatoes are a versatile veggie (or fruit, botanically speaking), and scientists have long been tinkering to improve their nutritional value and flavor. Now, a team of researchers has created a crop of cherry tomatoes that was gene edited to grow in a grape-like bunch, tailor-made for confined urban environments.

As Jennifer Leman writes in Popular Mechanics, tomatoes are not a particularly easy crop to cultivate—not least because they take up a fair amount of space with their long vines. Today, arable land is at a premium. Due to climate change, a quarter of the land that humans occupy is degraded, and more than 500 million people live in areas affected by soil erosion. One way to alleviate this problem, according to the authors of a new study in Nature Biotechnology, is to “grow more food in urban environments.” But to date, the benefits of urban agriculture have been limited by the small number of crops that can thrive in restricted conditions.

Hoping to produce a more compact tomato plant, the researchers tweaked three genes that influence the growth patterns of cherry tomatoes. The first two, known as the SELF PRUNING and SP5G genes, caused the tomato plant to stop growing sooner and produce flowers and fruits earlier. But altering these two genes alone reduced the tomatoes’ yield and sacrificed their flavor.

"When you're playing with plant maturation, you're playing with the whole system,” explains study co-author Zach Lippman, a plant biologist at the Cold Spring Harbor Laboratory in New York State, “and that system includes the sugars, where they're made—which is the leaves—and how they're distributed, which is to the fruits.”

A breakthrough came when Lippman and his colleagues identified a third gene, SIER, which controls the lengths of plant stems. According to Kat Eschner of Popular Science, the team used the CRISPR gene-editing tool to “turn off” all three genes—which in turn led to short stems and a compact bouquet of cherry tomatoes.

"They have a great small shape and size, [and] they taste good,” Lippman says, though he notes that the tomatoes’ flavor appeal “all depends on personal preference."

The tomatoes weren’t just tightly bunched; they also matured quickly, producing ready-to-harvest fruit in less than 40 days. This fruitfulness is another boon for urban farming, which can operate year-round in climate-controlled conditions. “More harvests per year results in more food, even if the space used is very small,” as the Cold Spring Harbor Laboratory points out.

Urban farms, though not without their drawbacks, have been touted for their environmental benefits, like reducing transportation distances—and the associated fossil fuel consumption—and stormwater runoff. One recent analysis found that urban agriculture has the potential to yield 10 percent of the global output of legumes, vegetables, roots and tubers if it is fully implemented in cities around the world.

Lippman tells Eschner that tomatoes seemed like a good place to start for his team’s experimentation because the plants are often grown in warm climates and shipped to the United States. Reducing their transportation distance could have an important environmental impact. Tomatoes also pair well, taste-wise, with leafy greens, which are the only plants currently being cultivated in vertical farms—crops that are grown on stacked shelves to maximize available space.

Urban farms aren’t the only institutions that stand to benefit from the new research. Figuring out how to successfully grow crops in tight areas is important for future missions to Mars, where astronauts will likely have to cultivate their own food during lengthy stays on the red planet .

"I can tell you that NASA scientists have expressed some interest in our new tomatoes," Lippman says.

The researchers’ genetic-tweaking focused on tomatoes, but they say that similar strategies could be used on other plants. Perhaps, in the future, we'll be munching on kiwis and cucumbers that grow in little bunches, too.

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