A Surprising Evolutionary Origin: The Potato’s Hybrid Roots

For centuries, the humble potato has been a staple on tables around the world, whether roasted, mashed, or fried. But scientists have long been puzzled by the exact genetic origins of this vital crop. Now, a groundbreaking study has revealed that the modern potato is the result of an ancient hybridization event between the ancestors of tomatoes and a plant known as Solanum etuberosum, occurring nearly 9 million years ago in South America.

The research, published in the journal Cell Press, was conducted by a multinational team of scientists from China, the United States, and the United Kingdom. Their analysis of 128 genomes uncovered a fascinating story: the modern potato, known as petota, has a mixed genetic ancestry derived from both Solanum etuberosum and tomato lineages.

According to Sandra Knapp, a plant taxonomist at the Natural History Museum in London and a co-author of the study, the hybridization event was a pivotal moment in the potato’s evolution. 'We had always known that potatoes, tomatoes, and Solanum etuberosum were closely related, but the relationship had been unclear,' she explained. 'Different parts of the genome told us different stories.' The new research has helped untangle this complex evolutionary history.

The team discovered that the hybridization event led to the development of tubers, the edible part of the potato. These structures allow the plant to reproduce without seeds and store water and carbohydrates, enabling it to survive in a variety of environments. This evolutionary leap allowed the petota lineage to diversify into over 100 wild species, as well as the cultivated potatoes we see in supermarkets today.

Interestingly, the hybridization event occurred around the same time that the Andes Mountains were forming between six and 10 million years ago. The emergence of these mountains likely played a role in shaping the potato’s ability to adapt to cold climates and thrive in the Andes and central Mexico.

While hybridization in plants is not uncommon, it has often been viewed as an 'evolutionary dead-end' because the resulting plants are usually sterile. However, the new study challenges this notion. Knapp emphasized that 'hybridization is a really potent force in evolution,' and the petota lineage is a prime example of this.

The researchers also highlighted the potential applications of their findings. By understanding the genetic mechanisms behind tuber formation, scientists may be able to develop new crops that are more resilient to disease, grow faster, and are more environmentally friendly. This could have significant implications for global food security and sustainable agriculture.

As lead author Zhiyang Zhang, a genomics expert from the Agricultural Genomics Institute at Shenzhen, noted, the study represents the 'most comprehensive collection of wild potato genomic data ever analysed.' This data not only sheds light on the potato's evolutionary past but also offers a roadmap for the future of crop development.

The study also raises intriguing questions about the potential for cross-species innovation. While one researcher jokingly suggested the creation of a 'tomtato'—a hybrid of tomato and potato—Knapp emphasized that the real value lies in improving the potatoes we already know and love. 'If we’re going to optimise crops, we want to optimise the thing we want from them,' she said. 'Usually, when you get something that does two things, those two things are not as good as the one that does the one thing better.'