Cell: modern potatoes appeared due to natural hybridization with tomatoes
Modern potatoes appeared as a result of natural crossbreeding with tomatoes, which occurred in South America about nine million years ago, according to an international study published in the journal Cell.
The origin of potatoes, one of the most important crops in the world, has long puzzled scientists. Externally, modern potatoes are almost identical to the three potato species of the genus Etuberosum from Chile, whose plants, however, do not form tubers. According to phylogenetic analysis, potato plants are more closely related to tomatoes. To resolve this contradiction, 450 genomes of cultivated and 56 species of wild potatoes were analyzed, the study says.
Scientists have found that each potato species contains a stable, balanced mixture of genetic material from both Etuberosum and tomato, suggesting that potatoes originated from ancient hybridization between the two.
Although Etuberosum and tomato are different species, they had a common ancestor about 14 million years ago. After diverging for about five million years, they were able to interbreed and gave rise to the earliest potato plants with tubers about nine million years ago.
Tubers allow potato plants to reproduce without seeds and pollination. New plants grow simply by sprouting from the buds on the tuber. This feature allowed them to quickly settle and occupy a variety of ecological niches in Central and South America.
“The emergence of the tuber gave potatoes a huge advantage in harsh conditions, which led to the emergence of many new species and contributed to the rich variety of potatoes that we see today,” Sanwen Huang, one of the study’s authors, told EurekAlert.
The researchers also traced the origin of key tuber formation genes in potatoes, which are a combination of genetic material from each parent. They found that the SP6A gene, which acts as the main switch telling the plant when to start forming tubers, was inherited from the tomato. Another important gene, IT1, which helps control the growth of underground tuberous stems, was inherited from Etuberosum. Without any of these genes, the hybrid offspring would be unable to produce tubers.
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