A genetically modified purple tomato is now available to home gardeners

As home gardeners in the U.S. page through seed catalogs and pick out their favorite heirlooms, there's a new seed that has never been available to them before: a tomato the color of a concord grape with plum-colored flesh. It looks otherworldly, maybe Photoshopped. But it's not.

This nightshade is purple because its creators at Norfolk Plant Sciences worked for about 20 years to hack color genes from a snapdragon flower into the plant. The genes not only provide pigment, but high levels of anthocyanin, a health-promoting compound.

This dusky fruit, named the Purple Tomato, is the first genetically modified food crop to be directly marketed to home gardeners – the seeds went on sale Saturday. Last year, a handful of small farmers started growing and selling the tomatoes, but until now, genetically modified foods were generally only available to commercial producers in the U.S.

By selling direct to gardeners, Norfolk hopes to get Americans to change their perceptions of GMO foods. A 2020 Pew Research study showed that most Americans see GMOs as worse for their health than a food that has no genetic modification and just 7% see them as healthier than other foods.

"We aim to show with this product and with this company that there's a lot of benefits that can go to consumers through biotechnology, better taste, better nutrition as prime examples," says Nathan Pumplin, CEO of Norfolk Healthy Produce, a subsidiary of Norfolk Plant Sciences.

A disease-fighting tomato

The leading scientist behind the Purple Tomato is Cathie Martin, a biochemist who trained at the University of Cambridge. About 20 years ago, she set out to create a transgenic tomato, using DNA from another unrelated organism, in this case, a purple snapdragon, which is an edible flower.

The goal was to develop a tomato with high levels of anthocyanins, the compounds that give blueberries and blackberries, eggplant and purple cabbage their color and their status as superfoods.

Anthocyanins have been shown to have anti-cancer and anti-inflammatory effects. They're antioxidants, which can help neutralize unstable molecules in the body that can damage healthy cells and are linked with aging and disease.

"It's normal for tomatoes to make these healthy antioxidants. They typically don't make them very much in the fruit, though," Pumplin says, explaining that they normally appear in the stems and leaves. "So what Cathie [Martin] did was put the on switch into tomato."

She started with the basic technique that scientists figured out in the 1980s using a bacteria to naturally insert its DNA into host organisms.

It's a process that can happen naturally. For example, sweet potatoes have the DNA of an agrobacterium and can technically be considered transgenic, an plant that contains genetic material of two different organisms.

Martin isolated the gene in the snapdragon flower that turned on and off the purple color. Next she took the gene and inserted it into the bacteria. The tomato could then take in the foreign genetic material and express this new gene.

"It really is a great example of understanding how the natural world functions and building on that to meet our needs," Pumplin explains.

The result? Norfolk's purple tomato has, per weight, as much anthocyanin as a blueberry or eggplant, Pumplin says. And Americans eat more tomatoes annually, so it makes the nutritional benefits more accessible.

In a research published in Nature, Martin found that mice who ate a diet supplemented with purple tomatoes lived 30% longer than those who didn't.

A new wave in GMO foods

The push for nutrient-dense GMOs is a recent trend, says Kathleen Hefferon, a microbiologist at Cornell University. The first wave of GMOs were for staple crops that were easier to grow.

"There was a real push of trying to achieve food security for a lot of populaces in developing countries and usually that involved making these staple crops that grew better, such as rice and corn and wheat and things like this," she explained.

A transgenic papaya was introduced to combat a virus that was destroying the crops in Hawaii. It's largely credited with saving the industry on the islands. There were also crops to increase nutritional value for populations in developing countries. Golden rice was developed in the late 1990s to have more beta-carotene to combat Vitamin A deficiencies. Because of practical and regulatory issues, the crop never took off.

The trend now is for biofortified foods, like the Purple Tomato.

"People have interest in their quality of life, for longevity and things like this. I think there has been just a health trend in that regard and it's going to continue," Hefferon says.

Along the same lines, California-based food company Fresh Del Monte created a pink pineapple in 2020. Its rosy flesh comes from a high level of lycopene, an antioxidant that gives peaches, tomatoes and watermelon their rosy hues.

But unlike the Purple Tomato, which the company is making widely available to both farmers and consumers, only Fresh Del Monte can grow it.

Traditional breeding vs. GMOs

Genetic modification in the lab isn't the only way to supercharge foods with nutrients, notes Jim Myers, a professor specializing in vegetable breeding at Oregon State University. He says in fact, traditional breeders were the first to release a tomato to the public with boosted levels of anthocyanins.

More than two decades ago Myers began using traditional plant breeding to cross genes from wild tomatoes with modern varieties.

The modern domesticated tomato originated from an 80,000 years old species from Ecuador. There are about 10,000 varieties of Solanum lycopersicum, which vary from marigold orange to celery green to khaki maroon

Domesticated tomatoes have anthocyanins only in the plant, but Myers says their wild relatives have them in the fruit.

He crossed Solanum cheesmaniae from the Galapagos and Solanum chilense from South America with a domesticated variety to ultimately create the Indigo collection of tomatoes.

In 2011, they released the 'Indigo Rose,' which has a deep blue skin and a pinkish inside when ripe, and more anthocyanin.

His first version of the tomato wasn't perfect, he says – the taste wasn't great and it took a long time to ripen, but subsequent breeding has improved on it, and gardeners can buy it and grow it themselves.

"I don't know if supercharging is the right word, but we're definitely enhancing their potential to provide benefits to human health," Myers says of the series, which now includes varieties like 'Indigo Cherry Drops', Indigo Pear Drops' 'Indigo Kiwi' and 'Midnight Roma'.

Myers points out that he and the creator of the Purple Tomato began working on these tomatoes at about the same time and there are now more than 50 cultivars of the Indigos being grown and bred throughout the world, including small farms and big companies.

"There's just all this diversity in the Indigo market class that has come about through conventional breeding," he says. "With the GMO tomato, it's taken them all this time and more to get one variety out there."

He also thinks the Purple Tomato could face a battle for acceptance that the Indigos don't, given negative perceptions of GMOs.

"There's going to be this cognitive dissonance for some people in that here is a tomato that has these potential health benefits ... contrasting with the origins, which was through genetic engineering."

A new chapter in the GMO debate?

Some of the earliest GM crops were corn and soybeans modified to tolerate herbicides like glyphosate, known commercially as Roundup. In 2023, the USDA reports 91% of domestic corn acres used herbicide tolerant seeds.

Mark Lynas, author of Seeds of Science: Why We Got It So Wrong On GMOs says the abundance of chemical-tolerant plants has harmed the acceptance of this technology.

"It enabled people who were concerned about the technology to really draw the conclusion that this was all about increasing agrochemical use, and the capture of the seeds in the food chain by big multinational corporations," he says.

Lynas says it was a blow to their adoption because the industry could have focused on genetic modifications that would actually use less herbicide.

"GMO technology could have already transformed world agriculture in a vastly more sustainable direction," he says.

The Purple Tomato's creators hope its release to gardeners could change the conversation. Lynas called Norfolk's marketing to consumers a "stroke of genius" that could demystify the technology.

"Stop just doing the GMO stuff with these big corporate, commodity cash crops and do something ordinary people can have in their hands," he says. "You'll see, actually it's just a seed which is going to produce a purple fruit, which is probably healthier for you."

Of course, some people have raised health concerns around eating GMOs, but studies since these foods were introduced three decades ago do not show any harm. The U.S. Food and Drug Administration concludes there is not a health risk to eating GM foods currently on the market.

Lynas says GMOs could be used to improve the environment, and livelihoods of people around the globe.

"If we focus on that, then we can make sure that these biotechnologies actually have outcomes and applications which are better for the planet and better for people overall. And that's the way that science should be used," Lynas says.

Pumplin measures success by whether or not a large number of consumers will embrace the health benefits, color and taste of the new tomato.

"Then it chips away at this negative perception of GMOs and that will enable other products to get out to market that deliver really solid benefits," he says. Benefits that include climate change, sustainability, health and nutrition.

Sáša Woodruff reports on food and agriculture. She is the news director of Boise State Public Radio.

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