Salad Days: Pairwise Gene Edits Food to Topple Nutrition Barriers

Food scientist and entrepreneur Haven Baker’s children are sick of kale. “My kids don’t want us to buy more salad kits with kale—they don’t want to eat it!” Baker told GEN Biotechnology. “They want to eat romaine lettuce.”

Baker’s kids aren’t alone. In households across the US, kids and adults alike want nothing to do with the leafy superfood. “While things like kale have a lot of nutrition, most people don’t want to eat [bitter] greens,” said Baker, the co-founder and Chief Business Officer at the food tech company Pairwise. “People want to eat lettuce, especially iceberg and romaine, which pack almost no nutrition.”

A little more than half of the population in the US eats their recommended daily allowance of vegetables, while one in ten people simply don’t have access to such luxuries. Despite all the best efforts in public education and other focus areas, these trends have not improved much for decades. Baker and the team at Pairwise aim to build a healthier world by using CRISPR genome editing  to develop novel nourishing foods that lower barriers to fruit and vegetable consumption, such as taste and accessibility. “We’re working on improving convenience and nutrition, increasing snacking ability, and making consumption easier,” Baker said.

Pairwise believes the use of technology offers a transformative opportunity to open a new horizon for the $66 billion U.S. retail produce market and is currently developing new fruits and vegetables. In 2023, Pairwise hopes to follow in the footsteps of Sanatech’s genetically edited Sicilian Rouge tomatoes being released into the Japanese market in September 2021 (Box 1). Rooted in North Carolina, Pairwise will sell several produce varieties “improved” by gene editing under the brand name Conscious Foods. The first product is Conscious Greens, which will be salad blends (Figure 1). Heading to the market after that are seedless blackberries and pitless cherries.

Pairwise announced $25 million in Series A funding in March 2018, led by Deerfield and what is now Leaps by Bayer, and $90 million in Series B in February 2021 to develop its gene editing platform and initial product portfolio. In 2018, the company also announced a $100 million collaboration with what is now Bayer Crop Science to advance gene editing tools in corn, soybeans, wheat, canola, and cotton.

Pairwise was launched in 2017 by a familiar trio of CRISPR gene editing experts: Broad Institute colleagues Feng Zhang, and David Liu, and Keith Joung, an investigator at Mass General Hospital. The three friends were also co-founders of Editas Medicine, the first CRISPR biotech company to go public. While these principal investigators are not exactly known for their prowess with plants, the utility of CRISPR and the untapped potential of genome editing in agbiotech made it almost inevitable that they would apply their expertise to farming rather than pharma.

To zero in on potential commercial products, Pairwise looks at the intersection of three perspectives: consumer benefit, scientific feasibility, and return on investment (ROI). The initial step is to find patterns in consumer data for what people want to eat and why. They’ve found that not all fruits and vegetables fit people’s modern lifestyles. For example, the introduction of baby carrots in the 1980s led to an increase in carrot consumption because they were easier to snack on and add to salads.

Baker says that the data shows that consumers want freshness and consistency, yet the quality of many fruits and vegetables changes from week to week or season to season. “If you look at blueberry consumption, it has gone up three to four times in the past 25 years, largely due to being made available year-round,” Baker said. “Are there any summer fruits that we would eat more of if they were available in good quality year-round? The response is, absolutely!”

Crisper with CRISPR

There is a lot of traditional breeding that has been employed in increasing production or making life easier for farmers, but more effort needs to be focused on making better food products for consumers faster.

“If you’re a cherry farmer, you’re worried about disease and yield, but if you’re a consumer of cherries, you’d really like to get rid of the pit and have them available year-round,” said Baker. “Sometimes, these products could be created through conventional breeding, but most of the time, if it could have been done within 50 or 100 years, it would’ve already been done.”

With the transformative potential of CRISPR, Pairwise is creating new crops based on consumer research (Figure 2). “We take these potentially viable products and use CRISPR to accelerate and bring those traits forward. With CRISPR, we can approach some of these fundamental problems that have hampered consumption and availability.”

Pairwise has also put a lot of money into developing technology that can quickly come up with a product idea for consumers. The company has raised $115 million in two funding rounds to help it improve gene editing technology for row crops and other plant-based uses. “We are innovating the editing technology to make new products or more products than we could two years ago,” said Aaron Hummel, Vice President of Research and Development at Pairwise.

GMO Intolerance

The Pairwise team is alert to the fact that previous attempts at plant genetic engineering have not been successful. Consumer acceptance of their products’ use of CRISPR technology appears to be aided by the fact that these crops aren’t classified as “genetically modified organisms” (GMO). Rather, they are referred to as “genome-edited.” To this end, there is no mention of GMOs, which typically refer to the practice of transferring genes between organisms and worry many consumers, on the Pairwise and Conscious Food websites.

This change in terminology may have significantly lessened the historical backlash against bioengineered plants. Recent studies show that attitudes toward gene editing in agriculture are changing (at least in the US), but most of the people who took part in the studies said they knew very little or nothing about the practice. People have heard of and are enthusiastic about CRISPR. When asked without more information, about half of the people who took part in the study agreed that gene editing is good for agriculture. However, after reading a short introduction, nearly two-thirds of them felt the same way.

According to Sarah Davidson Evanega, lead of stakeholder communication at Pairwise, the biggest confusion really revolves around language. She claimed that, despite their similarities in sound, genetic engineering and gene editing are very different in terms of how they are carried out. It serves as a reminder of how crucial using the appropriate language is.

Many of Pairwise’s products made with CRISPR require investigation to untangle the genes and pathways behind plant traits. Hummel said that plant tissues and biochemical pathways are very different in their complexity. Some of Pairwise’s plant variants are very simple, controlled by a single gene, and require just one edit to make them. But in other cases, the trait in question is multigenic, which means that several genes have effects that add up or work together. In these cases, it takes more than one edit to get the right phenotype.

Sometimes, plant biology is not fully understood and requires more discovery work. Hummel says that there have been cases where Pairwise has created a series of edits at a specific target gene, followed by phenotyping to see which variants best expressed the sought-after trait. Or sometimes, they might be in the dark about which gene to target. In these situations, Pairwise researchers usually assemble a set of gene targets to alter and test how they affect the target tissue. Either way, when doing this kind of discovery work, Hummel says they typically measure the trait in question and a couple of effects where the plant might compensate negatively.

The Not-So-Mean Mr. Mustard

Pairwise’s Conscious Greens are an example of how they do research and development to make new and better fruits and vegetables. With this product, the innovation is making mustard greens that are healthy, don’t taste spicy, and don’t have a strong smell. Pairwise found that consumers want more nutritious options for greens because they don’t like the taste of bitter greens. Pairwise was looking for ways to make salads healthier than just lettuce, so they focused on mustard greens, which have very healthy leaves but are too pungent for most salad lovers. The potential ROI also looked promising: packaged salads are a $10 billion industry and one of the largest parts of the supermarket produce aisle.

Chewing mustard greens produces compounds known as allyl-isothiocyanates, which are pungent and anti-herbivory (i.e., defense mechanisms against herbivore attack). As cells rupture from chewing, two physically separated molecules—a myrosinase enzyme and a glucosinolate precursor—mix and create allyl-isothiocyanate, also found in other pungent plants such as horseradish. But when cooked, the myrosinase enzyme gets broken down (denatured), preventing the reaction in the mustard greens’ leaves.

Hummel says that the team at Pairwise used gene editing to knock out the myrosinase gene, mimicking the effect of cooking and preventing the reaction that creates bitterness from occurring. Removing the gene to eliminate pungency required a fairly simple edit: a frameshift in the coding sequence, resulting in a loss of protein function.

But it wasn’t all straightforward. “The complex part of developing this product is because the mustard species is tetraploid, which led to many more targets in the genome that we had to knock out all simultaneously to get the full non-pungent effect,” Hummel said. “The edit was straightforward, but getting the right phenotype was pretty complex. The result is that the leaves are now non-pungent, and there’s a fairly pleasant flavor—it tastes relatively similar to lettuce, and the texture of the leaf is a lot like lettuce. So, we’re very excited about this as a better salad product.”

Miniaturized Mangoes and More

Baker says Conscious Greens will be available in select grocery stores and restaurants in the US in 2023. “We plan on launching Conscious Greens in regional retail markets next summer. We are now finishing product development and doing tests where we grow these in fields and run them through processing plants.”

Pairwise has sent out thousands of free samples to get feedback from customers, in part to find out if they’ve got the right crunch and color. Conscious Greens will have more than one edited variety of mustard greens, all of which should help make a very healthy salad mix. Patrick Hsu, co-founder of the Arc Institute and Assistant Professor of Bioengineering and Deb Faculty Fellow in the College of Engineering at the University of California, Berkeley, tweeted last summer that he was excited to try the world’s first CRISPR-edited salad from Conscious Foods.

In a decade or so, Baker envisions Pairwise selling bite-sized, healthy, and flavorful fruits and vegetables—mangos the size of cherries with edible skins available all year — to replace chips and Snickers as the snacks of the future. And he hopes that products like this will be joined in the produce section by many other foods and vegetables made by other CRISPR produce companies.

“This is going to change, hopefully in a positive way, all fruits and vegetables and eventually agriculture in a positive dimension. It will enable adaptations to climate change, disease resistance, and better profits for growers. There’s a growing recognition that we will need [gene editing] technology to solve these problems, especially in an era of food inflation. We need more productivity.”

GEN Biotechnology, published by Mary Ann Liebert, Inc., is the new, marquee peer-reviewed journal publishing outstanding original research and perspectives across all facets of the biotech industry. This article was originally published in the February 2023 issue of GEN Biotechnology, Volume 2, Issue 1. For more content like this and details on how to get a free subscription, go to 

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