The potato is one of the most important crops in the world and fed billions of people – but their origin has long been puzzling. Because the nutritious tuber plant shares characteristics with different plant lines that do not want to fit together: their closest genetic relatives are tomatoes, while their external appearance is reminiscent of tuberless chilean game species. Now it turns out: The potato apparently created through a primeval intersection from both – and for the first time developed the ability to form tuber.
Whether french fries, chips or puree: hardly any food is as versatile and popular as the potato. But while we have long since raised them to culinary cultural assets, their origin of research still puzzles. Because the plant from the family of night shadow plants combines characteristics that hardly seem to fit together: externally, it resembles potato -like game types from Chile, which are known as an etuberosum. These plants, like the potato, form above -ground drives and flowers, but no tubers. In turn, the potato of the tomato, which is also part of the nightshade plants, is closer. These contradictory findings led to decades of discussions about the origin of the potato – and in particular about the creation of their characteristic tubers.
Hybrid roots
Researchers around Zhiyang Zhang from the Chinese Academy of Agricultural Sciences have now got to the bottom of these supposed contradictions – with one of the most extensive genetic analyzes to the potato. In total, the team analyzed the genome of 450 cultural and 56 wild potato species. There were also reference genidates of other nightshade plants-including tomatoes and representatives of the etuberosum line. In order to gain the most precise insight into the descent history of the potato, the researchers not only seized complete genomes, but also haplotyped variants – i.e. inheritance information that can be viewed separately according to maternal and paternal line. Based on this data, the team compared the genetic patterns of the different types to draw conclusions about their common past.
The result: Each of the species of potato examined contains a stable, balanced mixture of genetic material of etuberosum and tomato plants, such as Zhang and his colleagues report. This genetic mosaic indicates that potatoes were once created at a natural crossing of representatives of both lines. The time process was probably the following: About 14 million years ago, etuberosum and tomatoes split off from a common ancestor. Five million years later, there was probably randomly hybridization. At this intersection of etuberosum and tomatoes, a primeval potato plant was created, from which today’s species developed over time.
Bulky advantages
With this intersection, however, not only a new plant line was created. It also produced a very special quality: the ability to form tuber. The researchers were able to show that two genes, each with one of the two parent lines, were responsible for this. The so-called sp6a gene, which signals the plant when it is supposed to train a tuber, comes from the tomato side of your family tree. The IT1 gene, which then controls the growth of the underground tubering stems, in turn comes from the Etuberosum side. Only if both genes are together can the potato plant form a tuber. This evolutionary innovation paid off quickly. Because with their tubers, the first potato plants were able to store nutrients underground – and thus also improve hard times such as dryness or cold. This was particularly important in the clinical locations of the Andes that were rapidly changing at the time.
“The development of a bulb gave potatoes an enormous advantage in rough environments, which led to an explosive increase in new species and contributed to the rich diversity of the potatoes that we know today and to which we rely on,” explains senior author Sanwen Huang.
Source: Zhiyang Zhang (Chinese Academy of Agricultural Sciences, Shenzhen) et al.; DOI: 10.1016/J.CELL.2025.06.034
