Why Scientists Want to Engineer Spicy Tomatoes

With genetic tinkering, the fruits may offer an easy source of capsaicin, the beneficial compound that gives peppers their heat

Heavybluesman via Wikimedia Commons under CC BY-SA 3.0 license

If you were asked to describe a tomato, words like “juicy,” “acidic” and maybe even “sweet” might pop into your mind. “Spicy” is not on the list of adjectives commonly attributed to this yummy fruit (and yes, it is a fruit), but that may one day change. As Nathaniel Scharping reports for Discover, a team of scientists hopes to genetically engineer tomatoes with a fiery kick.

The key to this challenge is capsaicin, the chemical compound that gives peppers their spicy taste by activating nerve cells in the tongue that deal with heat-induced pain. Because tomatoes are closely related to peppers—the two plants diverged 19 million years ago—they have all the genes necessary to produce capsaicinoids. But in tomatoes, these genes “are just not active,” Agustin Zsögön, co-author of a new report published in Trends in Plant Science, tells the Guardian’s Nicola Davis.

According to the paper, there are two ways that scientists can kick tomatoes’ capsaicin-producing abilities into high gear. One is through CRISPR, the gene-editing tool that can target DNA at precise locations. The other option involves Transcription Activator-Like Effector Nucleases (TALENs), which similarly target specific regions of the genome and have in the past been used to alter the genes of several plant species.

All of this, of course, begs the question: Why are scientists so keen to infuse tomatoes with a bit of spicy punch? In the past, researchers have mulled over possible ways to create better-tasting tomatoes, but the team behind the new study is not overly concerned with starting a new culinary trend. Instead, the researchers hope to make it easier to harvest capsaicin’s beneficial effects; the molecule has been shown to have anti-inflammatory, anti-oxidant and weight-loss properties. Capsaicin may even be helpful in fighting cancer. On top of that, Zsögön tells Davis, capsaicinoids “are used in [the] weapons industry for pepper spray [and] they are also used for anaesthetics.”

Capsaicinoids originate in the white pith of chilli peppers, which, unfortunately, are a rather finicky crop. They’re grown in open fields, leaving them susceptible to detrimental conditions like high precipitation and high temperatures, and their capsaicinoid levels can vary widely based on the environments in which they are cultivated. Peppers are also vulnerable to soil-borne diseases, and their seed germination can be quite slow. Contrast this with the hardy tomato, which is often grown indoors, has a high yield and is generally much easier to cultivate. Tomatoes, in other words, may offer a promising avenue for producing capsaicinoids at a commercial level.

Granted, we haven’t quite reached the point where chefs will no longer have to add extra heat to their tomato sauce. “We have the tools powerful enough to engineer the genome of any species,” notes Zsögön. “[T]he challenge is to know which gene to engineer and where.” Nor can scientists be sure how tinkering with tomato genes will affect factors like crop yield and quality. But even with those obstacles in mind, the study authors are optimistic. Spicy tomatoes, they write, could very well be “the next step in the fascinating story of pungent crops.”

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