STATE COLLEGE, PENNSYLVANIA—According to a statement released by Penn State University, Ivan López-Valdivia and Jonathan Lynch are investigating the domestication process of the wild grass teosinte into modern corn. The researchers used laser ablation tomography, which combines laser optics and 3-D imaging, to analyze the anatomy of two 5,000-year-old root stalks recovered from the very dry conditions in San Marcos Cave in southern Mexico’s Tehuacán Valley. Like modern corn plants, the roots’ outer cells had thick walls adapted to growth in hard soil. But unlike modern corn plants, the ancient plants lacked seminal roots, which supply corn seedlings with additional water and nutrients. Teosinte plants also lack seminal roots, López-Valdivia and Lynch explained. However, DNA analysis of a third ancient plant of similar age revealed the presence of mutations in two genes that contribute to the growth of seminal roots in modern corn plants. These genes may have been related to drought adaptation even though the traits were not yet expressed in the earliest corn from Tehuacán. For more, go to "How Grass Became Maize."