Potatoes Evolved From Tomatoes, Study Reveals

That’s it. That’s the news. Genome biologist Sanwen Huang knows a thing or two about potatoes. But his latest potato breakthrough may be his most shocking yet: potatoes are descended from tomatoes.

In a Cell paper published today, Huang’s team reports that the modern potato likely emerged about 9 million years ago, when tomato plants married the etuberosum, a potato-like species common to Chile. The origin of the modern potato has puzzled scientists for years, but the new results finally give plant genomists closure—while overturning a long-held belief that potatoes were solely descended from etuberosum.

“Yes, we revealed that the tomato is the mother of the potato,” Huang, a professor of agricultural genomics at the Chinese Academy of Agricultural Sciences, confirmed to Gizmodo.

Etuberosum, a type of wild potato, looks a lot like the potato you might find on a grocery shelf. But it lacks a key element of potato anatomy: the tuber—an extended structure of the stem or root that enables potatoes and their relatives to store nutrients and reproduce. Confusingly, however, genomic analyses suggested potatoes had much in common with tomatoes, Huang explained.

This hinted to scientists that the trio—potatoes, tomatoes, and etuberosum—were related, but the link wasn’t exactly clear. Until, that is, Huang’s team had a wild idea and decided to run with it. What if tomatoes and potatoes really were family and not just linked by some random quirk of nature?

To test their hypothesis, Huang and colleagues analyzed 450 genomes from cultivated potatoes and 56 other species of wild potatoes, constructing over 3,000 family trees to illustrate the genetic relationship between the modern potato, tomatoes, and the etuberosum. They found that 50.66% of these family trees listed tomatoes as a sister to petota, the group of wild potatoes with tubers. Next, they ran an extensive statistical analysis to compare the tree against genetic data. The team realized that the most salient scenario is that the potato is a hybrid of tomatoes and etuberosum, with the tomato contributing significantly more to the potato’s genetic makeup.

Most surprising of all was that the potato’s key tuber-forming genes emerged as a combination of genetic material it received from each parent—despite the fact that neither tomato nor etuberosum has tubers. Specifically, tomatoes gave potatoes the gene that tells the plant to make tubers, whereas etuberosum passed on a gene that helps control the growth of tubers.

This unique genetic pathway could lead to future agricultural innovations for breeding potatoes that don’t develop harmful mutations, Huang added. But that’s still in the works, and the potato expert hopes to explore this genetic relationship in more detail.

“Next time you eat potatoes, thank a tomato—the ancient, perhaps, mother of the potato,” Huang said. “DNA proves they’re family!”