Researchers Explore Corn Gene Combinations

Study at Purdue could help increase disease resistance, stress tolerance and plant yields.

Published on: Nov 20, 2008

A five-year study that could help increase disease resistance, stress tolerance and plant yields is under way at Purdue University.

The $4 million project uses a new technique called "mutant-assisted gene identification and characterization," or MAGIC, to identify potentially useful gene combinations in crop species.

"If we can understand these genes better, we could engineer plants to be immune to most diseases," says Guri Johal, an associate professor of botany and plant pathology.

First using the corn genome, the method will add to the collection of useful alleles, or pairs of genes, that create certain traits. This will improve crop gene diversity, a quality that dwindles as crops are bred. Since natural selection has preserved such alleles, they likely confer a selective advantage that increases the ability of plants to survive, Johal says.

Maize contains more genetic diversity than any other model organism, making it an ideal plant for gene exploration, Johal says. In fact, two lines of corn are more different from one another than humans are from chimpanzees, says study co-author Cliff Weil, a professor of agronomy.

"Maize grows in places as different as northern Quebec, where it is cold and growing seasons are short, and the Mexican highlands, where it is very hot and dry," he says. "Natural adaptation to different environments has come by combining just the right sets of alleles in each variation."

MAGIC is a new tool needed to find genes, Johal says. Many recent research methods used to this end involve mutagenesis, with scientists deliberately causing a specific gene or genes to malfunction in order to determine the gene's impact on the plant.

"Mutagenesis has worked well, but we are reaching a period of diminishing returns," Johal says. "We've identified most of the genes that have effects on their own, but now we need to understand how combinations of genes interact. We suggest going back to nature to find additional genes involved in a wide range of different processes."

Any genes discovered also could benefit other plants; all use the same pathway to fight infection, Johal said.

Weil and Johal are looking for natural genes that either enhance or diminish certain traits.
"We are basically 'mining' natural variation for genes of interest," Weil says.

"The nice thing is knowing this idea is going to work," Weil adds. “"The alleles, the variation in expression and the data to map them are already there. We will find a lot of things we expected and a whole lot of things we never even imagined."