Brian Gordon | (TNS) The News & Observer (Raleigh)

DURHAM, N.C. — Raw mustard greens, in their genetically unaltered form, leave a bitter aftertaste. Their flavor evokes horseradish or wasabi, lingering on the tongue until a chaser is found.

This astringency is caused by myrosinase, an enzyme that is liberated from the plant’s cells with each bite. Heat eliminates myrosinase, and cooked mustard greens are a staple of Southern cuisine, but the fresh greenish, purplish leaf is not widely beloved in salads.

The staff at Pairwise, a 6-year-old agricultural tech startup in Durham, believe this is a missed opportunity.

Nutrient rich, mustard greens possess more vitamin A than spinach and double the calcium. According to some studies, the vegetable even has more vitamin C than oranges.

This spring, Pairwise introduced the first food in the United States created with the genome-editing technology CRISPR. It’s a salad featuring non-pungent, myrosinase-free mustard greens that don’t leave consumers (including this reporter who sampled it in July) reaching for glasses of water.

“It’s both delicious and nutritious,” Pairwise CEO and cofounder Tom Adams said. “You don’t have to make a choice.”

In May, the company partnered with Virginia-based Performance Food Group Company to supply its unique greens to restaurants and dining halls across the country, though none in North Carolina. Pairwise’s baby mustard greens are now in 20 states, the company says, and early next year, it hopes to have its two blends — Green Zing and Purple Power — in grocery stores under the label Conscious Greens.

On Aug. 8, Pairwise announced a deal with the retail broker R² Fresh Solutions to help distribute its CRISPR-edited greens to regional grocers in the western United States. “We probably have enough supply for a few hundred grocery stores,” Adams said.

Mustard greens aren’t the only gene-edited produce Pairwise strives to commercialize. On the horizon, Adams says, are pitless cherries and seedless, thornless blackberries and raspberries.

Growing up and going public

Formed in 2017, Pairwise opened a lab in the life sciences-rich Research Triangle Park the following year.

One of the company’s main early investors was the agrochemical and biotech giant Monsanto, which Adams had left to help start his own company. In 2018, Monsanto was bought by the German biotech corporation Bayer, which recently completed a five-year collaboration with Pairwise.

In 2019, Pairwise entered a second location in Durham’s Golden Belt campus. Two funding rounds — raising $25 million and $90 million — gave the company the money it needed to increase production.

Today, Pairwise has around 160 employees. Going public is “Plan A,” Adams said, though a move to the stock market will likely wait until after another funding round and more business growth.

“We would like to be in a position where Conscious Greens has hit the market and is successful and we have the berry ready to go,” he said. “So, it would probably be 2026 or 2027 before we’d really be in that position.”

Nine steps to edit a plant

Pairwise grows its final produce in California and Arizona, but the company first develops its gene-edited fruits and vegetables in Durham.

The company outlines nine steps it takes to modify a green, berry or stone fruit. To begin, staff pinpoint the trait they seek to change and the gene that causes it. For mustard greens, its pungency and the gene that codes for myrosinase.

Food scientists then detect the gene sequence that impacts the undesirable trait and use CRISPR tools to enter the plant cells and turn off the expression of that gene.

“There might be 30,000 genes in a parent (plant),” Adams said. “You can keep the 29,999 the same and change the one.”

In its mustard greens, Pairwise scientists turned off 17 copies of the gene that codes for myrosinase.

The adjusted cells are then grown — with some graduating from small tissue culture vessels to growth chambers to greenhouses — as staff continuously monitor their new characteristics.

“One of the coolest things about plants is you can generate an entire plant from a single cell,” Adams said.

From seed to seed, a mustard green plant typically grows in 150 days. The final product looks regular — vibrant green and purple and veiny. After all, the vast majority of its genes are the same. But eliminating a single enzyme can make a difference.

How to market a gene-edited green?

In the United States, gene-edited foods do not have to carry identifying labels.

This differs from genetically modified organisms, or GMOs, which producers must disclose under federal standards. While GMOs give many pause, consumers are still sorting out their feelings toward newer gene-edited foods, says Christopher Cummings, a senior research fellow at North Carolina State University and Iowa State University.

In a 2022 study, Cummings found three in four Americans would want to know if their food had been genetically altered, with younger and wealthier people more likely to trust it.

“I think from at least a marketing standpoint, it’s important to be able to note that the product is distinct and that the edits that have been made to it are with the consumers best interest in mind,” he said.

Pairwise says it intends to be transparent when packages of Purple Power and Green Zing blends reach grocery stores.

“We are telling our story on the back of the package” said Sarah Evanega, a communications executive at Pairwise. “We also talk about the technology used to develop the products, and we have a little icon that says that better flavor through CRISPR.”

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