Remember when tomatoes didn’t just taste like water? Well, scientists have mapped the entire genome of hundreds of varieties of tomatoes, and identified the genetic traits that make them yummy. Tomato breeders could use this genetic roadmap to create tomatoes that have the original, rich fruit flavor that many of today’s commercial varieties lack. The future for tomatoes is looking up.
Most grocery store tomatoes are flavorless because breeders haven’t been selecting for taste. Instead they have selected the fruit for qualities such as yield, disease resistance, and firmness. Those are key for shipping and storing tomatoes long term before they’re displayed at your local grocery store. But all that came at the expense of flavor.
The new study, published today in Science, represents an exhaustive genetic analysis of many varieties, from heirloom to cherry tomatoes. Researchers asked consumers to rate more than 160 tomato samples to identify which tomatoes people like the most. Then, they determined which genetic variants are associated with specific flavor and aroma traits in those most-liked tomatoes. The results can work as the ultimate instruction book for breeders interested in putting more enjoyable tomatoes back on the market.
“You can almost assemble a molecular toolkit,” says study co-author Harry Klee, a professor of horticulture at the University of Florida. “We have identified a pathway to really significantly improve the flavor of tomatoes.”
Scientists have tried to address the flavor problem before. In fact, the very first genetically engineered crop to hit the market in the US in 1994 was a tomato. The so-called Flavr Savr tomato was engineered to stay riper longer. (Calgene, the biotech company that made the Flavr Savr, was eventually bought by Monsanto and the transgenic tomato was taken off the market.) A study also found that storing tomatoes in the fridge kills the flavor. But to get to the root of the flavor problem, understanding the genetics of the tomato is key, Klee says. “If you don’t start with good genetics, you’re never going to get good flavor,” he says.
In order to get to flavor, the scientists took a long road. First, they sequenced the whole genomes of 398 modern, heirloom, and wild varieties of tomato. They then selected 160 tomato samples, roughly representing a hundred varieties, and grew them in the lab. When they were ripe, the lab-grown tomatoes were harvested and given to a panel of 100 people for tasting. The study participants were asked to rate the tomatoes on taste. By comparing that information with their genetic analysis, Klee and his team were able to understand which genes were associated with flavors people enjoy. Now there’s a genetic roadmap for creating the chemical compounds, the sugars, acids, and aroma compounds that make tomatoes tasty.
“Tomato is much more complex in that the flavor is really a melting pot of lots of different chemicals that together makes you think, this is a tomato,” Klee says. This is different from bananas, strawberries, or pineapples for example, which have one dominant chemical that gives that fruit its distinct smell and taste. The tomato’s complicated chemistry made today’s work particularly challenging — and important.
Tomato breeders don’t have the resources to conduct a thorough genetic analysis and consumer panels, which are expensive, Klee says. This new research basically does the work for them and allows them to speed up the process. “A breeder can now simultaneously select for hundreds of these genetic markers to rapidly select new plants with as many of the desirable traits as possible,” Adrian Hegeman, a professor of horticultural science and plant and microbial biology at the University of Minnesota, who was not involved in the study, wrote in an email to The Verge. “This will make it easier to cross two different tomato varieties and test the progeny from that cross at very early stages of growth to get rid of plants that lack key gene linked traits.”
There are of course some limitations to what breeders will be able to do. The study shows that it may not always be possible to combine together all the desirable traits — good flavor and pest-resistance, high yield, and long storage life. In some tomato varieties, for example, some key genes linked to sweetness are also linked to the fruit’s smaller size. So if you want larger tomatoes, you’d probably need to give up that sweet tomato flavor.
Whether tomato breeders will actually use this study to create more flavorful tomatoes remains to be seen. The paper will probably have greater impact on tomato breeders and growers who provide produce for local markets and don’t have to worry about long-distance transportation, Changbin Chen, an assistant professor and tomato breeder at the University of Minnesota who was not involved in the study, wrote in an email to The Verge. For some commercial breeders, traits favored by growers rather than consumers will probably continue to dominate. And even if their favor genetics improve, some tomatoes will still taste like nothing; it’s common to pick tomatoes when they’re still green, so they’ll bruise less while being shipped and will look perfectly red and shiny by the time they’re in the produce aisle. An underripe tomato is not a tasty tomato.
For those willing tomato breeders out there, scientists today provided the ultimate guide to decoding the tomato flavor. Now we just need to wait. “I think [now] we know exactly how to make a much better flavor tomato, and it’s just a matter of time,” Klee says. “There’s no more discovery science that we need to do to make this happen.”