The Unexpected Roots of Potatoes: Where the World's Most Popular Product Came From

Potatoes are an agricultural crop that is popular among many peoples of the world. There are countless ways to cook them. But, while enjoying this member of the nightshade family, few people think about where it came from. Now scientists have given an answer to this question. The answer was unexpected.

Potatoes may have originated nine million years ago, according to a study published Thursday, from a cross between genetic material from Etuberosum, a group of potato-like plants native to South America, and wild tomatoes. Yes, tomatoes! So dipping your fries in ketchup might feel like reuniting distant cousins.

According to the study, this hybridization led to the potato plant's signature feature, the tuber, an underground structure that not only stores nutrients but was later discovered to be edible.

Zhiyang Zhang, a researcher at the Chinese Academy of Agricultural Sciences and lead author of the study, which was published in the journal Cell, described the beloved potato as "the child of tomato and Etuberosum."

Scientists have long noticed that the above-ground portion of modern potato plants is very similar to a subgroup of South American species, Etuberosum. However, Etuberosum does not have tubers. Genetically, potatoes appear to be more closely related to tomatoes. Both belong to the same genus, Solanum. This has caused confusion: why does a potato look like one plant but is related to another?

To solve this mystery, an international team of scientists analyzed 128 genomes from three sister lineages (tomato, Etuberosum, potato and their wild relatives), as well as three species of eggplant as an outgroup.

The modern potato was found to be of mixed origin, evolving from hybrid lines of tomato and Etuberosum eight to nine million years ago and giving rise to tubers.

This hybridization may have allowed subsequent potato species (there are now more than 100) to diversify and expand their range into the high Andes, where a colder climate prevailed.

The study shows that the genes responsible for tuber formation are a combination of genetic material from each evolutionary parent. The SP6A gene, which initiates tuber formation, comes from tomato, while the IT1 gene, which controls the growth of the underground stems from which tubers develop, comes from Etuberosum.

Another lead author from the Chinese Academy of Agricultural Sciences, Pingxiang Zhang, is excited about the prospects for future research, noting that genetic engineering of potatoes using tomato genetic material could be a promising direction for development.

Over the past few years, researchers have been able to analyze genomes on a much larger scale than before, revealing previously opaque evolutionary relationships.

Richard Veillot, a horticulturist at Virginia Tech who has traced the origins of cultivated potatoes back thousands of years, called the study "a creative use of genomics."