There’s scarcely a corner of the world that doesn’t like a good peanut in their cuisine. But for years, these legumes have had a mysterious backstory. Now, thanks to the discovery of a “living relic” wild peanut plant, scientists have traced back the biological origins of the humble legume.
It has long been assumed that the modern-day peanut was a hybrid of two types of wild peanut – Arachis duranensis and Arachis ipaensis – native to the Andes somewhere between Argentina and Bolivia. But actual evidence of the A. ipaensis species has eluded scientists for years. Unconfirmed reports have popped up here and there, but the species was thought to be extinct.
However, researchers from the University of Georgia and the International Peanut Genome Initiative have recently found a live specimen of A. ipaensis in the foothills of the Bolivian Andes. After DNA analysis, the science confirmed that the peanut we all know and love was in fact the product of this hybridization. Their findings are published in Nature Genetics.
DNA analysis showed that the wild A. ipaensis and the modern peanut were 99.96 percent genetically identical. But oddly, the A. duranensis peanut is actually known to be native to an area hundreds of miles south of A. ipaensis. Using molecular DNA clock calculations, the team worked out that the plant’s seeds were “almost certainly” transported by humans about 10,000 years ago. The hybridization was then simply carried out by nature, likely via a native bee.
"It's almost as if we had traveled back in time and sampled the same plant that gave rise to cultivated peanuts from the gardens of these ancient people," said David Bertioli, an International Peanut Genome Initiative plant geneticist from the Universidade de Brasília.
A mother feeds her son the peanut-based Plumpy'Nut in Tigray Region, Ethiopia. Image credit: UNICEF Ethiopia/Flickr. (CC BY-NC-ND 2.0)
Tracing the origin story of the peanut is an important task. Peanuts provide a low-cost source of vegetable protein that many regions of the world, including those facing malnutrition, rely on. For example, Plumpy'Nut is a peanut-based paste that can be used to treat acute malnutrition. The paste is high in energy, doesn't require clean water to swallow and doesn't need refrigeration. Experts have said that the paste has "radically" changed the care of severely malnourished children in developing countries.
This latest research could be used by future studies to discover more productive and more resilient peanut varieties. With this last piece of the puzzle filled, researchers can access 96 percent of all peanut genes. This has provided them the opportunity to create a DNA map of the peanut, allowing them to easily identify and modify genes that code for desirable traits, such as disease resistance.
Victor Nwosu, program manager for Mars Chocolate and chairman of the board of directors of The Peanut Foundation, said: "The peanut genome project will lead to reduction in production costs through development of disease-resistant varieties and improved yield for farmers, speed of selection and release of new varieties for breeders and potential for improvement of nutritional value of peanuts for consumers.
"We are beginning to see these benefits already," he added.
[H/T: Scientific American]