‘This wasn’t obvious’: the potato evolved from a tomato ancestor, researchers find | Biology

Regarding the senses, there could not be any greater difference between Friday evening chips and juicy Mediterranean tomatoes.

However, scientists have discovered that these two foods are not so far from each other after all. Historical research revealed that the potato was evolving from a tomato ancestor almost 9 million years ago.

Wild tomatoes, which have developed in the Andes, crossed with a plant called Etuberosum, and through a process called hybridization, they mixed their genetic equipment to form an entirely new line.

“The tomato is the mother and Etuberosum is the father,” said Sanwen Huang, professor at the Institute of Agricultural Genomics in Shenzhen, China, who managed the research team. “But it was not easy at first.”

Above the ground, potatoes seem almost identical to the Etuberosum. But pull them up and the difference is clear: Etuberosum has thin underground stems and none of the starchy potato tubers that make it a global base food.

To explain the tubers, scientists turned to tomato. Although he does not produce tubers, he shares a surprisingly similar genetic profile. “They belong to the same family of plants, as well as eggplant and tobacco, but tomato, potato and study are genetically closest,” said Huang. “So we decided to zoom in.”

As described in Cell, the team analyzed 450 cultivated potatoes and 56 of wild species. “This is one of the largest genomic collections of wild potatoes ever analyzed,” said the first author, Zhiyang Zhang.

The team discovered that two genes were crucial for making tubers: SP6A, found in the tomato, and it1, found in Etuberosum. None of the two genes is enough in itself. But when the two combine, as in the potato plant, they interact, triggering the powerful process which transforms the underground stems into starch and tasty tubers.

“The study is revolutionary,” said James Mallet, professor of organizational biology and evolving at Harvard University. “This shows how a hybridization event can trigger the emergence of a new organ – and even lead to a new line with many species.”

The potatoes inherited a stable mixture of genes from both parents, making it a robust and resilient plant. His tubers store energy, helping him to survive winter or drought and allowing him to reproduce without needing seeds or pollinators. Instead, the new plants grow from buds that grow on the tubers.

The nutrient -rich organs have helped the potatoes to thrive in the new high altitude habitats of the Andes increasing. The plants have adapted and spread, leading to an explosion of diversity. Humans have a number of wild species, selecting those with large edible tubers.

“The Aboriginal peoples of the Andes have hundreds of potato varieties,” said Dr. Sandra Knapp, botanist at the Natural History Museum in London. “In Europe, we may have five – all of one species: Solanum Tuberosum.“”

The potato left the Andes on board Spanish ships in the 16th century. Initially encountered suspicion – he grew up underground, was not in the Bible and looked strange – he was quickly adopted for his nutrition and his ability to bear bad conditions. It has become a staple food across Europe and the whole world.

We do not know what is the next step for this adaptable plant, because his closest parents have diverged too far for natural hybridization to happen again. But researchers explore artificial means to create new varieties.

“We are working on a project that helps potatoes reproduce by the seeds,” said Professor Huang. “And we put the IT1 genes and other potato genes with tomato, so that it can grow tubers.”

For the moment, everything is experimental. But if it works, the tomato will not only be part of the past of the potato – it could also be part of its future.