While the chilli pepper and tomato split off from a common ancestor 19 million years ago, it turns out they still share some of the same DNA.
The fleshy tomato stands in sharp contrast to the more agriculturally difficult chilli plant that contains capsaicinoids, molecules that give peppers their spiciness.
Now scientists say that with the latest gene-editing techniques, it could be possible to make a tomato produce capsaicinoids as well or in other words, it is possible to make spicy tomato.
The article, published in the journal Trends in Plant Science, says that the objective is not to start a new culinary fad (though the authors do not deny it completely either) but to have an easier way to mass produce capsaicinoids for commercial purposes. Capsaicinoids on their part have nutritional and antibiotic properties that are used in painkillers and pepper spray.
Speaking about the study, senior author Augustin Zsogon, a plant biologist at the Federal University of Viçosa in Brazil said, “Engineering the capsaicinoid genetic pathway to the tomato would make it easier and cheaper to produce this compound, which has very interesting applications.”
The spicy aftertaste that capsaicinoids produce is not its taste but rather a reaction to pain. Having chillies activate nerve cells in the tongue that deal with heat-induced pain, which the brain interprets as a burning feeling.
Evidence suggests that the evolution of capsaicinoids helped chilli peppers deter small mammals from eating their fruit. Birds, which are much better seed dispersers, show no pain response to the molecules.
The spiciness of a pepper is determined by the genes that regulate capsaicinoid production, and less pungent peppers have mutations affecting this process. And while previous gene sequencing work has shown that tomatoes have the genes necessary for capsaicinoids, the study also found that they don’t have the machinery to turn them on.
Speaking about using genes to produce capsaicinoids in tomato, Zsogon said, “Since we don’t have solid data about the expression patterns of the capsaicinoid pathway in the tomato fruit, we have to try alternative approaches. One is to activate candidate genes one at a time and see what happens, which compounds are produced. We are trying this and a few other things.”
The sequencing of the chilli pepper genome and the discovery that the tomato has the genes necessary for creating a fiery flavour paves the way for engineering a spicy tomato.
According to the researchers, not only will the endeavour help understand the evolution of the tomato and chilli, but perhaps allow for the development of some new varieties of produce as well.