Tomato plants are grown in long rows, collected when they turn a greenish-orange hue, and then hauled into storage until they are gassed with ethylene to start the ripening process. But as Lippman says, nature hasn’t given farmers enough mutations to play with, at least not on a practical timescale. Additional mutations could relieve compact growth to make plants a bit larger, thereby increasing fruit yield. Before CRISPR, Lippman had to treat seeds with chemicals that randomly mutagenize the DNA and then manually search for desirable mutations by scouring row after row of tomatoes. He spent four years compiling a toolkit of new mutations, where several mutations worked collectively to build a higher-yield tomato plant. There had to be an easier way.
CRISPR technology is not about introducing foreign DNA, but working with the plant’s own DNA and enhancing natural repair processes. For example, a desirable trait in tomatoes is called jointless, in which the stem leading to the fruit lacks a knuckle or joint. Fresh market tomatoes crossbred with the jointless trait enables high-throughput production and less damage during handling. Lippman’s group used CRISPR to engineer a jointless line of tomatoes without having to cross different strains, and can apply this to any variety.16 His lab has also introduced mutations in the promoter of the self-pruning (SP) gene to create a sort of genetic rheostat, tuning the degree of inactivation to help growers adapt tomatoes to more northern latitudes with longer days but shorter growing seasons.17
Another fruit of interest is the humble groundcherry (also known as a strawberry tomato). A native plant of Central America, the groundcherry is an orphan crop that never made it in the agricultural major leagues. It’s drought-resistant and has a “tropically intoxicating” flavor, Lippman says, but they have long branches and the fruit are fussy to grow. Using CRISPR, Lippman seeks to shortcut thousands of years of selective breeding by introducing several gene edits, influencing traits such as plant size and architecture, fruit size, and flower production.18 Green groundcherries are naturally the size of marbles, but disrupting the CLAVATA1 gene produces fruit that are 25 percent larger. Moreover, modifying the groundcherry counterpart to the SP gene produces more compact plants that are easier to harvest.19
CRISPR edits are not GMOs. Whereas CRISPR cuts the genome in a precise spot, it is the cell’s natural DNA repair process that stitches the ends back together. The resulting mutation is no different than what might arise using chemical mutagens or X-rays or occur naturally. That is the enlightened verdict of the U.S. Department of Agriculture (USDA), which decided to treat CRISPR edits no differently than other methods of mutagenesis.
But the Europeans disagreed. In 2018, the European Court of Justice (ECJ) ruled that gene-edited crops do fall under GMO guidelines. Criticism rained down from all quarters: “illogical,” “absurd,” and “catastrophic” were representative reviews. Lynas said the ruling was “like saying doctors can use [a] blunderbuss but not [a] scalpel.” Placing CRISPR and GMOs in the same bucket was like “the Catholic Church classifying ducks as fish,” lamented Ewan Birney, a prominent British geneticist. Clive Brown, the chief technology officer of Oxford Nanopore, fumed: “If only these twits”—the ECJ—“realized that all of their beloved vegetables and most farm animals are hideous mutants.” And British Conservative MP Owen Paterson said the European Union was condemning itself to become “the world museum of farming.”20
In China, genome-edited crops are currently regulated as GMOs, but discussions with the Chinese government will likely turn things around. “We are hoping for a better solution than in Europe,” says Gao Caixia, a plant biologist at the Chinese Academy of Sciences in Beijing.21
We have a global food problem. Worldwide, says Mick Watson, a geneticist at the Roslin Institute, there are about a billion people in the world who are obese and a billion people who are hungry. “This should be a problem that’s pretty easy to solve, by taking the food away from the obese people.”22 Watson’s facetious sense of humor may not be to everyone’s taste but it does not diminish a serious message. The growing world population means that over the next fifty years, the world’s farmers will have to produce more food than in the past 10,000 years combined. This has ramifications for the CRISPR craze, too. Imagine if we were able to cure all diseases, using CRISPR and other medical innovations. Watson says we wouldn’t all live forever—we’d die of starvation.
The commercial potential of genome editing in the plant world has not been lost on the CRISPR community. With few exceptions, fruit and vegetable consumption in the United States has not improved in fifty years. There are some interesting exceptions, which have nothing to do with biotechnology. Introduced in 1986, the baby carrot has led to a dramatic increase in carrot consumption—3.8 billion pounds of the vegetable per year. In 2008, improvements in farming enabled blueberries to be delivered across the country year-round, resulting in a doubling of annual consumption to 600 million tons.
In 2017, Feng Zhang, David Liu, and Keith Joung, three cofounders of Editas, decided to get the band back together to apply their genome-editing prowess to plants. Pairwise Plants secured a five-year deal with Bayer, owner of Monsanto, to develop improved row crops and boost farm productivity, aiming to make foods that are more affordable, convenient, and sustainable.
Gene editing does not introduce a foreign gene, as happens in GMOs—but introduces a specific change to the DNA, usually to a sequence that already exists in nature. Besides speed and specificity, gene editing offers another benefit. Traditional selection leads to a loss of genetic diversity as lines are crossed and back-crossed. Gene editing can introduce traits without backcrossing, preserving or reintroducing lost variation. Early studies have used CRISPR-Cas12a to cut genes in corn and soybeans.
Gene-edited plant products made a high-temperature, low-key debut in the United States in March 2019, as the donut-frying oil at the Minnesota State Fair. Calyxt, a subsidiary of the French biotech company Cellectis, introduced Calyno, a gene-edited high oleic soybean oil. The oil has zero trans fats and 20 percent less saturated fat than its counterpart. Ironically, most of the soybean oil produced in the US is genetically modified, but Calyxt thinks Calyno—modified using TALENs rather than CRISPR—will prove a healthy, more neutrally flavored alternative to olive oil.
Calyxt says its gene-editing approach will give the American people “healthier food ingredients without compromising the taste of what they already love.” For cofounder Voytas, that means a household staple: “We’d like a piece of Wonder Bread to meet all your daily requirements of fiber.”23 Thanks to the USDA regulations, Calyno proudly sports a “non-GMO” label, which doesn’t sit well with environmental groups that refuse to recognize the distinction between genome editing and transgenic modification. Calyxt’s edited soybean plants in South Dakota and Corteva’s “waxy” high-starch corn in Iowa—destined for emulsifiers and glue sticks—are just the first seedlings in a forest of gene-edited crops and foods destined for consumers and livestock, from wheat and potatoes to alfalfa plants.
In China, much of Gao Caixia’s efforts are on improving wheat, which imposes an extra two degrees of difficulty. The wheat genome is three times larger than the human genome and even larger than corn, soybean, or rice. Moreover, the wheat genome is hexaploid, meaning it has not one pair of chromosomes (a diploid genome) but three pairs. This extra redundancy means gene editors have to work three times as hard to target a particular gene. But Gao’s team has engineered wheat lines that are resistant to powdery mildew24 and herbicide resistance by inactivating the acetolactate synthase gene.25 She’s also engineering tomatoes like Lippman to change the plant’s architecture, flowering time, and vitamin C content.