Study Sheds Light on Plant-Pathogen Interaction in Soybean

At the Iowa State University, plant pathologists Thomas Baum, Steve Whitham and Martijn van de Mortel looked for molecular  changes occurring in soybean during soybean rust infection. By studying the interaction between soybean and the Asian soybean rust fungus while a plant is being infected, they hope that in the future a soybean variety with broad-spectrum resistance could be developed.

The researchers sprayed Asian soybean rust spores on two soybean varieties - a highly susceptible variety and a resistant one in which the disease progresses slowly. Both varieties immediately responded to the fungus as indicated by significant changes in gene expression levels. But after 24 hours into the infection, the plant's response to the rust pathogen turned off. The activity peaked again as another response was mounted - first in the variety with resistance to the disease; a day or two later in the highly susceptible variety.

"It looked like this second burst of gene activity in the resistant plants was the real resistance response," Whitham said. It's likely the fungus produced something the plant recognized as foreign." From the study, the scientists have been able to narrow down the field of candidate genes involved in the defense of soybean against rust infection from 37,500 genes to a few hundred.

Read the press release at http://www.iastate.edu/~nscentral/news/2007/aug/asianrust.shtml.