First tamed about 10,000 years ago, the humble modern potato began on Mount Andean before it became an important crop that the world depends on. However, the plant is not well preserved in the fossil record, so its lineage remains primarily a mystery.
Now, a team of evolutionary biologists and genomic scientists have come across the origins of this starchy staple diet millions of years ago, involving tomatoes, a relative of a plant.
Researchers analyzed 450 genomes of cultivated wild potato species, and the genes revealed that the ancestors of ancient wild tomato plants naturally raised potato-like plants called echuberosams 9 million years ago.
Neither tomato nor etvelosum had the ability to grow tubers – domesticated edible parts such as potatoes, yams, and taros that grow underground – the resulting hybrid plants did. Tubers have evolved as an innovative way for potato plants to preserve nutrients underground as the Andean climate and environment become colder. Currently, there are over 100 wild potato species that also grow tubers, but some contain toxins so not all are edible.
“Evolving into tubers, potatoes offer great benefits in harsh environments, spurring new species explosions, and contribute to the rich diversity of potatoes that we see today.” “We have finally solved the mystery of where potatoes came from.”
Scientists deciphered which genes were fed from each plant to create tubers in the first place. Understanding how potatoes emerged and evolved can help scientists breed disease-resistant, more resilient potatoes and change climatic conditions.
Potatoes, tomatoes and ethovelosum all belong to the genus Solanum, which includes around 1,500 species, and are the largest genus in the Night Shade family of flowering plants. At first glance, the potato plant looks almost the same as Echuberosam. This initially led scientists to think that the two are sisters from a common ancestor, and Jianquan Liu, a co-author of the study, is Jianquan Liu, a professor at a university at Lanzhou University in Ganshu, China.
Etoberosam contains only three species, and the plant has flowers and leaves similar to potato plants, but does not produce tubers.
“Echuberosum is something special,” Dr. Sandy Knapp, research author and research botanist at the Museum of Natural History in London, told CNN. “If you were in the Juan Fernandez Islands, the Robinson Crusoe Islands in the middle of the Pacific Ocean, or in the rainforest of a Chilean temple, you probably never see.”
However, drawing the potato, tomato and echuberosum lineage revealed unexpected wrinkles that indicate that potatoes are more closely related to tomatoes on a genetic level, Nap said.
The team used phylogenetic analysis, a similar process to determining parent-daughter or sister-sister relationships in humans, to determine relationships between different plants.
The analysis showed inconsistency. Potatoes could be sisters of etvelosum or tomatoes, depending on the different genetic markers, Liu said.
The 14 million years of common ancestors of tomatoes and etbelosum, and plants that branch out from them, no longer existed, and “were lost in the mist of a geological age,” Nap said. Instead, researchers looked for genetic markers within the plant to determine their origin.
“What we use is signals born from the past, and plants today are still in plants that are trying to reconstruct the past,” Knap said.
To track that signal over time, researchers have compiled a potato genetic database, including looking at museum specimens, obtaining data from rare wild potatoes that are difficult to find, and from rare wild potatoes occurring in a single valley in the Andean.
“Sampling wild potatoes is extremely difficult, so this dataset represents the most comprehensive collection of wild potato genomic data analyzed to date,” said Zhiyang Zhang, a researcher at the Institute of Agricultural Genomics at the Academy of Agricultural Sciences, in a statement.
This study revealed that the first potato, and all subsequent potato species, contained a combination of genetic material derived from ethovelosum and tomato.
Climate or geological changes are likely to result in the coexistence of ancient etbelosum and tomato ancestors in the same place, Liu said.
Amy Schalkowski, Associate Dean of Research at Colorado State University’s Agricultural Sciences University, says that given both species being bee-pollinated, it is likely that the bees have moved pollen between the two plants, leading to potato creation. Charkowski was not involved in any new research.
The tomato side provided the “master switch” SP6A gene, instructing potato plants to begin production of tubers, while the IT1 gene on the etuberosam side controlled the growth of the rhizome that formed starchy tubers, Liu said. Researchers say that if either gene was deficient or did not function in the concert, the potato would not have formed tubers.
“One of the things that happen with hybridization is that genes get confused,” Nap said. “It’s like shuffling a deck of cards again, with different cards coming out in different combinations. And in this particular hybridization event, two types of genes came together to create the ability to nodulate.
The evolution of tuber potatoes coincided with the era when the Andes mountain range rapidly rose due to interactions between the tectonic plates that produced giant spines in the west of South America, Knap said. The Andes are complex mountain ranges with numerous valleys and various ecosystems.
Modern tomatoes, like dry, hot environments, prefer temperate spaces. However, the ancestors of potato plants have evolved to allow tubers to survive ultimately and thrive in the arid, cold, high-altitude habitats born across the Andes, Knap said. Potatoes can be reproduced without the need for seeds or pollination. The growth of new tubers leads to new plants, which can thrive in a variety of environments.
The cultivated potatoes we consume today are currently the third most important staple crop in the world, using wheat, rice and corn, and according to research, they are responsible for 80% of human calorie intake.
Understanding the story of potato origin may be the key to breeding more innovations in future potatoes. Reintroduction of the major tomato genes could lead to the breeding of potatoes that are bred by the species Huang and his team of the Chinese Academy of Agricultural Sciences are experimenting with.
Modern crops are facing pressure from environmental changes, the climate crisis and new pests and diseases, Knap said.
Seed potatoes are interesting as they are more genetically diverse and may be resistant to disease and other agricultural risks. When potatoes are cut into small pieces, planted and vegetatively propagated to produce crops, new diseases produce genetically identical potatoes that can be wiped out.
It may also be important to study wild species that have emerged and evolved in response to such challenges, she added.
Charkowski’s lab is interested in how wild potatoes resist disease and why pests and diseases in some plants affect only potatoes and tomatoes.
“In addition to helping to understand potato evolution and potato tuber development, the methods used (in this study) also help researchers learn about other traits, such as disease and insect resistance, nutrition, drought tolerance, and many other important plant traits of potatoes and tomatoes,” said Charkowski.
Potatoes continue to be important crops in arid or regions with short summers and highlands. It’s a place where other major crops don’t grow, she said.
The findings also show that potatoes view them from a different perspective. This was the result of a chance encounter between two very different individuals, said Dr. Tina Selkinen, an expert on Edinburgh’s night shades in the royal botanical garden.
“It’s actually very romantic,” she said. “The origins of many of our species are not simple, and thanks to the abundant genomic data, it is extremely exciting to be able to discover these intertwined, complex origins.”
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