Brazilian connection yields RNA for rust research
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| Innoculations done at 10 pm. |
Martijn van de Mortel's "commute" is longer than most.
Van de Mortel, a postdoctoral researcher in Iowa State's plant pathology department, traveled to Brazil twice this summer. His trips will help researchers learn how soybean plants respond to rust infection at the molecular level.
Rust, a fungus that invaded South America a few years ago and appeared in the southern United States last fall, makes soybean plants shed leaves prematurely, cutting yields by as much as 80 percent. It was expected to strike Iowa and the Midwest this summer, but it hasn't arrived.
Van de Mortel traveled to Londrina, Brazil, to work in the greenhouses and labs of EMBRAPA Soja, the Brazilian equivalent of the U.S. Department of Agriculture Agricultural Research Service. "EMBRAPA selected the soybean lines we used. They have the rust fungus and they have the know-how to inoculate plants with it," van de Mortel said.
Researchers raised two sets of plants: a susceptible variety and a variety in which the disease progresses slowly. Researchers sprayed one-half of the plants from each variety with water containing rust spores. They sprayed the other half of the plants with plain water as a control.
Van de Mortel sampled leaf tissue and extracted RNA, the product of gene expression, from it. The RNA gives a "snapshot" of what genes are active or inactive at a given time.
"What we're hoping is that there is a set of genes that turns on early in infection and sets up all the genetic effects after that," said Steven Whitham, assistant professor of plant pathology. Sampling leaves over time will give a comprehensive picture of the disease's effects on the activities of soybean genes, he said.
The experiment was conducted in Brazil, where rust already is prevalent, to prevent the introduction of spores in the United States. The RNA samples van de Mortel brings from Brazil aren't infectious.
The researchers will use Iowa State's gene chip facility to analyze the samples for gene expression. Each chip tests for the activity of about 33,000 soybean genes. The rust research will use 120 of the chips, creating huge amounts of data for the scientists to sort.
"That probably is the most challenging aspect of the project," Whitham said. "There's a steep learning curve when you start analyzing data for 33,000 genes." Nonetheless, Whitham hopes the team will have some early results next spring.
