The scientists used bread wheat species to find the gene and the markers, or bits of DNA, that indicate presence of the naturally occurring gene. The fungus causes wheat crop damage worldwide with yield losses of 50 percent or more in some places. In the United States the disease is widespread in the Pacific Northwest, the northern Great Plains and the eastern Midwest soft wheat region, and experts estimate annual losses at $275 million.

Results of the Purdue study on resistance to the fungus that causes Septoria tritici leaf blotch are published in the September issue of Phytopathology and appear on the journal's Web site at http://www.apsnet.org/phyto/.

"The goal of our work is to find additional resistance genes to the fungus Mycosphaerella graminicola so we can use the lines carrying these genes in our wheat to avoid the breakdown of resistance in the plants," said Stephen Goodwin, associate professor of botany and plant pathology and U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) scientist. "Having the markers greatly speeds up the breeding process for resistant plants."

The markers facilitate finding plants with the pathogen resistance gene. As soon as a seedling sprouts, a small piece of the young leaf can be ground and then a DNA test can be run. This shows whether the markers are present.

"Using the markers, in a few days you can tell which plants have the resistance gene and which don't," Goodwin said.

The researchers discovered the gene Stb8, so named because it is the eighth gene known to provide resistance to Septoria tritici leaf blotch (STB). However, this gene has some differences compared with the ones found p
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Contact: Susan A. Steeves
ssteeves@purdue.edu
765-496-7481
Purdue University
20-Aug-2003