The modern potato is a descendant of the tomato: scientists have solved an evolutionary mystery

It turned out that about 9 million years ago in the wild in South America there was a natural crossbreeding between the ancestors of modern tomatoes and potato-like plants.

It was this ancient hybrid that gave rise to the modern potato, Cell Press reported.

In a study published in the journal Cell, scientists say this event triggered the formation of tubers - underground nutrient-storing thickenings characteristic of potatoes, yams and taro.

"Our findings show how crossbreeding between different species can lead to the emergence of new traits and even the formation of new species," notes lead author Sanwen Huang of the Chinese Academy of Agricultural Sciences. - "We have finally solved the mystery of the origin of potatoes."

Potatoes are one of the world's most important crops, but their evolutionary roots have long remained obscure to science. Externally, modern potatoes look very similar to three wild species from Chile known as Etuberosum, but these plants do not form tubers. Phylogenetic analysis showed that the closest relative of the potato was the tomato, which only confused the situation.

To unravel this paradox, the researchers analysed the genomes of 450 cultivated potato varieties and 56 wild species. According to Zhiyang Zhang, the paper's first author, this is the most extensive collection of genetic data on wild potato species ever conducted.

The results showed that all modern potato plants contain a balanced set of genes from both Etuberosum and tomato, confirming the origin of potatoes through ancient interspecific hybridisation.

Although Etuberosum and tomato are different species, they shared a common ancestor some 14 million years ago. Even after 5 million years of independent evolution, they were able to interbreed, leading to the first potato plants with tubers about 9 million years ago.

Scientists were also able to discover the origin of key genes responsible for tuber formation. For example, the SP6A gene, which triggers tuber formation, was inherited from tomato, and another important gene, IT1, responsible for the growth of underground stems, came from Etuberosum. Without these genes, the hybrid could not form tubers.

The evolutionary leap coincided with the rapid rise of the Andes and the formation of new ecological zones. Thanks to the tuber's ability to store nutrients underground, potatoes began to adapt quickly to variable conditions, surviving harsh climatic periods in the mountains.

Moreover, tubers allow potatoes to reproduce without seeds or pollination: a new plant can grow from an "eye" on a tuber. This ability has facilitated the potato's rapid spread across landscapes ranging from warm grasslands to cold mountainous regions in Central and South America.

"The emergence of the tuber gave the potato a huge evolutionary advantage in difficult environments, stimulated the emergence of new species and provided the enormous diversity we enjoy today," emphasises Juan.