Scientists have pinpointed a single letter change in the genetic script of corn's ancestor, teosinte, that stripped away the crop's outer layer and made it edible to humans.
The findings reveal how a single nucleotide change in the teosinte glume architectural gene (tga1) allowed corn to become the "king" crop across most of the globe, the University of Wisconsin - Madison reported.
"A huge proportion of the world is economically dependent on the crop and understanding how it was constructed 10,000 years ago is more than just intellectually satisfying," said UW-Madison professor John Doebley.
Teosinte looked much different from the corn we know today; the wild grass was bushy with tiny "ears" containing between 10 and 12 rock-hard kernels. Despite these vast differences, maize's origins were traced back to Teosinte in southwestern Mexico.
"The big question is, when we look out the window and see a diversity of forms in the plants and animals around us, what were the genetic changes that took place to make all of that happen?" Doebley said. "Two closely related plants, why do they have a different shape of leaf; or two people, why is one a little taller?"
The researchers determined this small, human-driven was responsible for the transformation of corn. To make their findings, the researchers looked at six potential mutations in the tga1 gene. They studied a large number of corn and teosinte genomes to land on the exact one that led to the dramatic change.
The team determined this single letter change created a difference in the protein made by tga1, which influence a number of features of teosinte by switching other genes on and off. This change prevented the hard fruitcase surrounding the teosinte kernel from developing, and instead moved it to the cob.
"So, the kernel ends up naked, uncovered and exposed on the surface of the corn cob, to be eaten," Doebley said.
The findings were published in a recent edition of the journal Genetics.
