No wonder tomatoes are among the most beloved fruits of all time, adding a fresh sparkle to food countless times around the world every day, thanks to their versatility in culinary inside planting and preparation as well as high nutritional values. Nevertheless, a battle has always existed between growing larger, higher-yielding tomatoes versus breeding for taste. Consumers prefer sweeter tomatoes; however, this higher sugar content is often lost in the drive to increase fruit size and yield. Well, a new study published in Nature has broken through this trade-off, so we can have sweeter tomatoes without lower yield, potentially solving this problem for farmers and consumers alike.
The research team, which includes lead authors Jinzhe Zhang and Sanwen Huang, wanted to understand how the two genes SlCDPK27 and SlCDPK26 work together to regulate sugar content in tomatoes. These genes serve as a “brake” to sugar accumulation by phosphorylating an important enzyme called sucrose synthase. Using genome editing to knock out mutations in these genes, the researchers effectively released the brakes. As a result, glucose and fructose, which are the primary sugars that make fruit sweet, were elevated in the fruit.
Key Facts:
- Edited genes act as “sugar brakes,” boosting glucose and fructose by up to 30%.
- Sugar boost did not affect fruit size or yield.
- Genes SlCDPK27 and SlCDPK26 regulate sugar in tomatoes.
- A 12-base-pair insertion in SlCDPK27 linked to higher sugar, recovering lost traits.
The study has one major breeding success, which is that the increased sugar levels did not compromise fruit size or yield, a perennial problem with previous breeding strategies. Typically, tomatoes are less sweet because larger fruits share resources in the plant-derived carbohydrates that produce sugars. In addition, this breakthrough showed that the best of both worlds could be achieved: in a commercial growing setting, it was indeed possible to boost tomato sweetness without losing fruit size and yield.
Utilizing CRISPR-Cas9 gene-editing technology, the researchers knocked out two genes named SlCDPK27 and SlCDPK26 in cultivated tomato lines. This method resulted in more than 30 percent greater concentrations of glucose and fructose in the edited plants compared to their unedited counterparts. Fruit weight and sweetness were unaffected by the engineering approach, suggesting a homeostatic role for producer and transporter.
Among the most important findings of the study was identifying a single mutation, a 12-base-pair insertion in the promoter region of SlCDPK27, which is a DNA sequence that controls when and how much a gene is expressed—that correlated with greater sugar content. However, during the course of tomato evolution, this mutation appears to have been lost through selective breeding aimed towards larger fruit size and increased yield in modern cultivars. Researchers were able to regain the lost balance between sweetness and size caused by domestication of the fruit simply by reintroducing this genetic trait.
However, the research went beyond the laboratory. To achieve this, the team had two large-scale consumer panels of around 100 volunteers to a taste test to compare the sweetness of gene-edited tomatoes to conventional ones. The results were clear: the edited tomatoes were consistently rated as sweeter, validating that the increase in sugar levels translated directly into a more appealing taste experience.
According to Dr. Harry Klee, a co-author of the study, that is important because it opens up new possibilities for tomato breeding, which could make a major difference in breeding for tomatoes in the near future. Dr. Klee added, “What we’ve done here is strike a compromise that both producers and consumers can live with—a better-tasting fruit that doesn’t mean sacrificing yield.” The development has wider implications not just for tomatoes but also for other fruits and vegetables where sugar content is related to consumer preference.
These results are also significant for the understanding of the molecular basis of sugar metabolism regulation in tomato plants. The study may provide a blueprint for similar approaches to other traits: knocking out genes whose presence limit undesirable features—in this case, sugar accumulation—to boost desirable ones. Thus, it paves the way for targeted gene editing, which increases food quality without compromising productivity—a farmer’s dilemma across the world where market quality and yield are often at odds with each other.
Besides making tomatoes taste sweeter, the study provides a broader context of effects from sugar storage within fruit. The plants had fewer lighter seeds, but the germination rate was unaffected. It indicates that the resources normally allocated to seed creation were available for increasing sugar concentrations in the fruit, thus yielding a tastier tomato. The researchers found that while numbers of seeds did drop slightly, that is unlikely to impact the success of the plants in farmland.
In the future, they plan to investigate how this gene-editing method can be taken up at larger scales and hope it will continue to benefit other consumers—preferred crops such as strawberries, grapes, and melons—which are also important for organoleptic quality by modulating sweetness. Noting this fact, one may even think that the commercial application of the produced CRISPR-Cas9 sweetness-enhanced tomatoes could be imminent, as its technology has already been widely used in Japan on other fruits like GABA-enriched tomatoes. Cardinal Foods imports and markets these tomatoes as soon as they land on grocery store shelves across the globe. Food science has reached an exciting juncture, according to Dr. Zhang: “We are beginning to appreciate that the flavor traits lost in these crops as agriculture became increasingly industrialized can be reintroduced.”
This success demonstrates the potential improvement of not only yield but also quality in the nutritional and sensory aspects of fruits and vegetables using state-of-the-art gene-editing tools, which is important for consumers and can set a new food industry standard.
All in all, these data are not only about tomatoes. They mark a movement towards quality instead of only quantity in food production. “Our research illustrates that there are both nutritional and taste enhancements to some of our favorite foods possible with the help of science breaking down age-old trade-offs,” another co-author, Sanwen Huang, added.
For more, visit: https://doi.org/10.1038/s41586-024-08186-2
