New research in the journal Cell says the crop we eat today began 8–9 million years ago after a rare natural mix between two wild plants in South America, in what scientists describe as a case where tomato mated potato at a genetic level: an ancestor of tomatoes and a small group called Etuberosum. Neither parent made tubers. But when their genes combined, a new organ formed underground the tuber and the first potatoes appeared in the Andes.
This clear finding helps explain how one of the world’s most important foods began and why it became so successful in tough places. The work also shows how hybridization, or mating between different species, can quickly create new traits.
For a long time, scientists noticed that potatoes look a lot like three Chilean species in the Etuberosum group, even though those plants do not make tubers. At the same time, DNA studies kept saying potatoes are closer to tomatoes. To solve the mystery, an international team compared genomes across the whole potato family tree.
They examined 450 cultivated potato varieties, 56 wild species, and a broader set of 128 plants from the Tomato, Petota (the potato lineage), and Etuberosum groups. The patterns were “mosaic-like,” with a stable and balanced mix of DNA from tomato-side and Etuberosum ancestors in every potato they checked. That is strong evidence that potatoes began as a hybrid and then formed a new lineage called Petota.
The team also traced the origin of tuber-making to two genes with different parents. From the tomato side came SP6A, a master switch that tells the plant when to start forming tubers. From the Etuberosum side came IT1, which helps build the underground stems that swell into tubers. Without the timing signal from SP6A and the building plan from IT1, the hybrid would not make potatoes at all. Together, these genes created a powerful survival tool under the soil.
The timing of this genetic “match” mattered. Around 8–9 million years ago, the Andes Mountains were rising fast. Colder, drier conditions spread, and many plants struggled. With tubers storing energy and water underground, early potatoes could survive harsh seasons and grow back when conditions improved.
Tubers also let potatoes spread without seeds or pollination, because a single tuber can sprout new plants. This simple ability helped potatoes colonize new habitats quickly, from mild grasslands to high, cold meadows across Central and South America. It later drove a burst of new potato species influenced by the ancient moment when tomato mated potato.
“We’ve finally solved the mystery of where potatoes came from,” said corresponding author Sanwen Huang of the Chinese Academy of Agricultural Sciences.
Sandra Knapp of the Natural History Museum in London said interbreeding created new gene combinations, while first author Zhiyang Zhang highlighted the depth of genomic data used.
The study also reminds us that useful traits can come from wild relatives. By studying this ancient event where tomato mated potato, scientists may now breed stronger crops for the future.
Tomato and Etuberosum share a common ancestor from about 13–14 million years ago. Even after millions of years of separation, they were still able to interbreed in the wild. That rare event launched the potato lineage 8–9 million years ago.
