DURHAM, N.C. -- Scientists continue to debate the ancestry of domesticated corn. But Duke University researcher Mary Eubanks said she has mounting evidence that corn emerged from the interbreeding of two different wild American grasses.

Those grasses are Tripsacum dactyloides, also known as Eastern gamagrass, and Zea diploperennis, a perennial variety of teosinte. By successfully crossing them for the first time, Eubanks has produced fertile offspring that closely resemble the earliest known samples of primitive domesticated corn, she said in a recent interview.

Patented lines of her crosses are fertile over several generations and carry genetic traits that are "missing links" in corn's evolution, Eubanks adds in the latest issue of the journal Theoretical and Applied Genetics.

That article updates experiments originally described in the June, 1995 issue of Economic Botany. She will report on her work again at an August meeting of the American Institute of Biological Sciences in Montreal.

If Tripsacum is indeed a corn ancestor, then breeders could take advantage of some of the special traits of that hardy ubiquitous plant, the Duke botany research scientist said.

Indeed, Eubanks has crossed her lines with modern corn to produce hybrids that share Tripsacum's resistance to the corn rootworm. That's the root-eating juvenile -- or larval -- stage of an insect that costs corn farmers $1 billion a year in crop losses and pesticide expenses.

In preliminary experiments at Duke's Phytotron, a high-tech greenhouse where she rents space, Eubanks found far less root damage and far fewer larvae in her experimental hybrids than occurs in normal commercial corn.

"We're using the western corn rootworm, which is the most serious pest in the Midwest," she said. "It's an incredible problem and a big expense for corn growers. Because they don't know where they are going to have an outbreak, they
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Contact: Monte Basgall
monte@dukenews.duke.edu
919-681-8057
Duke University
4-Jun-1997