The crossbreeding of South American tomato plants with potato-like species approximately 8 million years ago resulted in the development of modern potatoes (Sun Chronology). A collaborative team of biologists from China, Canada, Germany, the US, and the UK indicates that this ancient evolutionary milestone led to the emergence of tubers, an expanded underground structure used for storing nutrients in plants like potatoes, yams, and taros.
Interspecies hybridization can drive species radiation by generating various allelic combinations and traits. While all 107 wild relatives of cultivated potatoes and petota lineage share characteristics of subterranean tubers, the exact mechanisms of nodulation and extensive species diversification remain unclear. An analysis of 128 genomes, including 88 haplotype-degraded genomes, indicates that Zhang et al believe Petota is of ancient hybrid origin, revealing stable mixed genome ancestors derived from ethoberosam and tomato strains approximately 8 to 9 million years ago. Image credit: Zhang et al., doi: 10.1016/j.cell.2025.06.034.
Cultivated potatoes rank as the third most crucial staple crop globally, alongside wheat, rice, and corn, contributing to 80% of human calorie consumption.
In terms of appearance, modern potato plants are similar to three potato-like species found in Chile, known as Etuverosam. However, they do not produce tubers.
Phylogenetic analysis reveals that potato plants are more closely related to tomatoes.
To clarify this discrepancy, Dr. Sanwen Huang, PhD, from the Institute for Agricultural Genomics at Shenzhen, China, along with colleagues, analyzed 450 genomes of cultivated and 56 wild potatoes.
“Our research shows how interspecies hybridization can instigate the emergence of new traits and lead to the formation of more species,” explained Dr. Huang.
“We have finally unraveled the mystery of potato origins.”
“Collecting samples of wild potatoes has been extremely challenging, making this dataset the most comprehensive collection of wild potato genomic data analyzed to date,” noted Dr. Zhiyang Zhang, a researcher at the Institute of Agricultural Genomics at Shenzhen, China Academy of Agricultural Sciences.
The researchers discovered that all potato species contained a stable mix of genetic material from both exo root and tomato plants, indicating that potatoes originated from ancient hybridization between the two.
Although Etuberosam and tomatoes are distinct species, they share a common ancestor from around 14 million years ago.
Even after diverging for about 5 million years, they still managed to interbreed, resulting in the earliest potato plants exhibiting tubers approximately 8-9 million years ago.
The team also traced the origins of key tuber-forming genes in potatoes, which comprise genetic contributions from both parent species.
They identified the gene SP6A, functioning as a master switch indicating when plants should begin tuber formation, originating from the tomato lineage.
Another crucial gene, it1, derived from the Echuberosum lineage, assists in regulating the growth of underground stems that develop into tubers.
Hybrid offspring require both components to produce tubers.
This evolutionary advancement coincided with the rapid uplift of the Andes, a period when new ecological environments emerged.
The ability to store nutrients in tubers enabled early potatoes to adapt quickly to changing conditions and withstand the harsh mountain climate.
Moreover, tubers facilitate a mode of propagation without seeds or pollination, allowing new plants to grow from tuber buds.
This adaptability enabled them to expand swiftly from temperate grasslands to cold alpine pastures across Central and South America, filling various ecological niches.
“The evolution of tubers has provided potatoes with significant advantages in challenging environments, fostering the emergence of new species and contributing to the incredible diversity of potatoes we now depend on,” Dr. Huang concluded.
The study was published in the journal Cell on July 31, 2025.
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Zhiyang Zhang et al. Ancient hybridization underpins the diversification and radiation of potato lines. Cell Published online on July 31, 2025. doi: 10.1016/j.cell.2025.06.034
Source: www.sci.news
