It’s one of those odd thoughts that may cross through many people's minds late at night: Where do peanuts come from?
Peanut-shaped pottery and peanut-decorated jars from Brazil date back 3,500 years, but scientists have never been sure exactly what ancient plants the globally important crop originated from. Researchers thought that the modern peanut, Arachia hypogaea, formed when two South American wild legumes, Arachis duranensis and Arachis ipaensis, cross-pollinated. Now, genetic research shows this hypothesis is correct, and it will revolutionize the way peanut varieties are bred.
A. ipaensis was thought to be extinct until a collector recently rediscovered it in a Bolivian village. But even more curious about this rare species is that it grows hundreds of miles north of A. duranensis, which lives in the foothills of the Andes on the border of Bolivia and Argentina. Scientists wondered how the two species ever got together in the first place.
So researchers from the University of Georgia and the International Peanut Genome Initiative dug into the peanut history by studying the DNA of old botanical collections, according to a press release. Based on this information, they could roughly pin down when the two species cross-pollinated and compared that date with data on the migration of early South American peoples. The results of this study were recently published in the journal Nature Genetics.
“We now know that the first inhabitants of South America in their long voyages carried A. ipaensis to the land of A. duranensis 10,000 years ago," the study's lead author David Bertioli of the University of Brasilia and UGA tells Andrea Small Cardona at Scientific American. "Once in the same area, bees pollinized the peanut plant flowers, allowing the birth of the hybrid that our South American ancestors ate and that eventually led to the modern peanut.”
The researchers also sequenced the genomes of all three species, learning that the modern peanut has 20 pairs of chromosomes, inheriting 10 chromosomes each from its ancestral cousins. Understanding the peanut genome better gives researchers the ability to find markers for disease resistance, heat tolerance, and insect and drought resistance. This will help them cultivate peanut varieties that thrive in conditions around the world.
“We did it because knowing the genome sequence like this is a really powerful thing for breeding better varieties and for understanding how peanuts might be made better,” Bertioli tells The Christian Science Monitor.
The peanut has had a huge impacts on human history, and Bertioli says it will become even more important as we struggle to feed the world over the next century. “The hybrid peanut crop spread throughout South America in pre-Columbian times, reaching the shores of the Atlantic and Pacific and even into Central America and Mexico,” he tells Cardona. “After colonization it was carried to Africa, Asia, North America and Australia, sites where it became an important crop. It is a food that has lived during many interesting times.”