PSI Initiative Jump-Starts Asian Soybean Rust Research
The Plant Sciences Institute launched a set of research initiatives in 2004 to address challenges to Iowa agriculture and several have begun to pay off. One success story addresses a threat to our soybean crop, caused by the Asian soybean rust fungus.
The Asian soybean rust project was initiated before the pathogen had even been reported in the United States. The Institute's Center for Plant Responses to Environmental Stresses (CPRES) deemed it a research priority and the focus of its Crop Protection Research Initiative because the disease can devastate soybean crops. In severe infestation outbreaks, it can wipe out 80 percent of soybean yields and spread rapidly depending on environmental conditions.
The initiative funded the work of Thomas Baum and Steve Whitham, faculty members in the plant pathology department and affiliates of CPRES, and plant pathology postdoctoral researcher, Martijn van de Mortel.
The results of their work were published as a "Spotlight" story in the August issue of Molecular Plant-Microbe Interactions. "Distinct BiPhasic mRNA Changes in Response to Asian Soybean Rust Infection," describes the results and conclusions of experiments that measured the levels of gene expression in two groups of plants exposed to the rust fungus: a susceptible variety and a variety in which the disease progresses slowly.
Results of the study showed that within the first 12 hours in both susceptible and less susceptible plants, pathogen inoculation induced substantial gene expression changes.
"What was surprising though was that 24 hours into the infection, gene expression returned to the baseline—the plant's response to the rust pathogen essentially turns off," said Whitham.
Later, gene expression changes in response to rust infection turned on again, Whitham said, likely because the fungus produced something the plant recognized as foreign. But it happens a day or two earlier in the resistant plants, indicating that these genes may be involved in regulating or affecting soybean defense mechanisms. Overall, the experiment has helped narrow down the search for genes involved in defending the soybean plant from 37,500 to a few hundred.
"The real use of our work is that we generated a huge genomic resource that we and everybody else in the world can now use for further study," said Baum. "The Crop Protection Research Initiative served its function to address an imminent need that poses a threat to crops in Iowa, and we used these seed funds to create a new research project."
Baum, Whitham and van de Mortel will continue the Asian soybean rust research with funding from the Iowa Soybean Association.
