The trendy potato developed from a wild tomato fling 9 million years in the past, scientists say

NEW YORK — The humble modern-day potato, first domesticated about 10,000 years in the past, acquired its begin within the Andes mountains earlier than changing into a key crop the world relies on. But as a result of crops do not protect properly within the fossil document, its lineage has remained largely a thriller.

Now, a staff of evolutionary biologists and genomic scientists has traced the origins of this starchy staple to an opportunity encounter hundreds of thousands of years in the past involving an unlikely plant relative: the tomato.

The researchers analyzed 450 genomes from cultivated and wild potato species, and the genes revealed that an historic wild tomato plant ancestor naturally bred with a potato-like plant known as Etuberosum 9 million years in the past — or interbred, as each crops had initially break up off from a standard ancestor plant about 14 million years in the past, in keeping with a research printed Thursday within the journal Cell.

While neither tomatoes or Etuberosums had the flexibility to develop tubers — the enlarged, edible a part of domesticated crops akin to potatoes, yams and taros that develop underground — the ensuing hybrid plant did. Tubers developed as an progressive method for the potato plant to retailer vitamins underground because the local weather and atmosphere within the Andes turned colder — and as soon as cultivated, resulted in a dietary mainstay for people. There at the moment are greater than 100 wild potato species that additionally develop tubers, though not all are edible as a result of some comprise toxins.

“Evolving a tuber gave potatoes a huge advantage in harsh environments, fueling an explosion of new species and contributing to the rich diversity of potatoes we see and rely on today,” research co-author Sanwen Huang, president of the Chinese Academy of Tropical Agricultural Sciences and a professor on the Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, mentioned in an announcement. “We’ve finally solved the mystery of where potatoes came from.”

The scientists have additionally decoded which genes have been provided by every plant to create tubers within the first place. Understanding how potatoes originated and developed may in the end assist scientists breed extra resilient potatoes which can be proof against illness and shifting local weather circumstances.

Digging into the spud’s enduring thriller

Potatoes, tomatoes and Etuberosums all belong to the genus Solanum, which incorporates about 1,500 species and is the most important genus within the nightshade household of flowering crops. At first look, potato crops look almost similar to Etuberosum, which initially led scientists to assume that the 2 have been sisters that got here from a standard ancestor, mentioned research co-author JianQuan Liu, a professor within the school of ecology at Lanzhou University in Gansu, China.

Etuberosums embody simply three species, and whereas the crops have flowers and leaves just like these of potato crops, they do not produce tubers.

“Etuberosums are a special thing,” Dr. Sandy Knapp, research co-author and analysis botanist on the Natural History Museum in London, instructed CNN. “They’re things that you probably would never see unless you went to the Juan Fernandes Islands, the Robinson Crusoe Islands in the middle of the Pacific, or if you were in the temple rainforest of Chile.”

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We’ve lastly solved the thriller of the place potatoes got here from.

–Sanwen Huang, professor on the Agricultural Genomics Institute at Shenzhen

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But charting out the lineage of potatoes, tomatoes and Etuberosums revealed an surprising wrinkle that appeared to point that potatoes have been extra intently associated to tomatoes on a genetic degree, Knapp mentioned.

The staff used phylogenetic analyses —a course of just like figuring out in people a parent-daughter or sister-sister relationship on a genetic degree — to find out the relationships among the many totally different crops, Liu mentioned.

The evaluation confirmed a contradiction: Potatoes may very well be a sister to Etuberosums or tomatoes, relying on totally different genetic markers, Liu mentioned.

The 14 million-year-old widespread ancestor of tomatoes and Etuberosums, and the crops that diverged from it, do not exist anymore and “are lost in the mists of geological time,” Knapp mentioned. Instead, the researchers appeared for genetic markers throughout the crops to find out their origins.

“What we use is a signal that’s come through from the past, which is still there in the plants that we have today, to try to reconstruct the past,” Knapp mentioned.

To observe that sign by way of time, the researchers compiled a genetic database for potatoes, together with taking a look at museum specimens and even retrieving information from uncommon wild potatoes which can be arduous to seek out, a few of them occurring in only a single valley within the Andes, Knapp mentioned.

“Wild potatoes are very difficult to sample, so this dataset represents the most comprehensive collection of wild potato genomic data ever analyzed,” research co-author Zhiyang Zhang, a researcher for the Agricultural Genomics Institute at Shenzhen on the Chinese Academy of Agricultural Sciences, mentioned in an announcement.

A genetic highway map written by probability

The analysis revealed that the primary potato, and each subsequent potato species, included a mix of genetic materials that derived from Etuberosums and tomatoes.

Climatic or geological modifications possible brought on an historic Etuberosum and a tomato ancestor to coexist in the identical place, Liu mentioned.

Given that each species are bee-pollinated, the possible state of affairs is {that a} bee moved pollen between the 2 crops and led to the creation of the potato, mentioned Amy Charkowski, analysis affiliate dean of Colorado State University’s College of Agricultural Sciences. Charkowski was not concerned within the new analysis.

The tomato facet provided a “master switch” SP6A gene, which instructed the potato plant to begin making tubers, whereas a IT1 gene from the Etuberosum facet managed the expansion of the underground stems that fashioned the starchy tubers, Liu mentioned. If both gene have been lacking or did not work in live performance, potatoes by no means would have fashioned tubers, in keeping with the researchers.

“One of the things that happens in hybridization is that genes get mixed up,” Knapp mentioned. “It’s like shuffling a deck of cards again, and different cards come up in different combinations. And fortunately for this particular hybridization event, two sorts of genes came together, which created the ability to tuberize, and that’s a chance event.”

The evolution of tuberous potatoes coincided with a time when the Andes mountains have been quickly rising as a result of interactions amongst tectonic plates, which created an enormous backbone down the western facet of South America, Knapp mentioned. The Andes are a posh mountain vary with quite a few valleys and a variety of ecosystems.

Modern tomatoes like dry, sizzling environments, whereas Etuberosums choose a temperate house. But the ancestor of the potato plant developed to thrive within the dry, chilly, high-altitude habitats that sprang up throughout the Andes, with the tuber enabling its final survival, Knapp mentioned. Potatoes may reproduce with out the necessity for seeds or pollination. The development of latest tubers led to new crops, they usually may flourish throughout various environments.

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What we use is a sign that is come by way of from the previous, which continues to be there within the crops that we’ve at present, to attempt to reconstruct the previous,

–Dr. Sandy Knapp, analysis botanist on the Natural History Museum in London

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The cultivated potato we eat at present is presently the world’s third most necessary staple crop, and with wheat, rice and maize, is accountable for 80% of human caloric consumption, in keeping with the research.

Understanding the potato’s origin story may very well be the important thing to breeding extra innovation into future potatoes; reintroducing key tomato genes may result in fast-breeding potatoes reproduced by seeds, one thing with which Huang and his staff on the Chinese Academy of Agricultural Sciences are experimenting.