58-Year-Old Corn Gene Mystery Unraveled

When scientists discovered a mutant gene that "turns on" another gene responsible for the red pigments seen in corn, they also solved an almost six-decades-old mystery with a finding that may have implications for plant breeding in the future. The mystery involved a spontaneous gene mutation causing red pigments to show up in various corn plant tissues for a few generations and then disappear in subsequent progeny. It seemed like a minor concern, but because corn genetics have long been studied as a model system, the question has significant implications for plant biology. Surinder Chopra, professor of maize genetics at Penn State led efforts to introgress the genes from a mutant corn, dubbed Ufo1 — Unstable factor for orange1 — into various inbred corn lines to be studied. However, Ufo1 is not causing the red pigments to appear, but a gene called pericarp color1 or p1. Researchers found that the Ufo1 gene is actually controlled by a transposon that sits close to it. When this transposon is switched on, the Ufo1 gene is also turned on, triggering the p1 gene to signal the plant to produce the red pigments. When the transposon is off, the Ufo1 gene goes silent and so does the p1-controlled pigment pathway. Chopra said that this is the main reason the Ufo1 gene went unidentified for so long and the mystery persisted. (Source: Crop Biotech Update, International Service for Acquisition of Agri-Biotech Applications. www.isaaa.org)