URBANA, Ill. — Illinois wheat growers, take heart. A University of Illinois study shows no evidence of a highly toxic Fusarium head blight (FHB) variant, known as NA2, in the wheat-growing region of the state.
The study also reinforces the effectiveness of wheat resistance to the fungal disease.
“The fact that we didn’t find any signs of the NA2 population in central and southern Illinois is good news for growers. It seems the pathogen is not very well adapted to warmer climates. For the time being, we think all the FHB out there is the NA1 type,” Santiago Mideros, assistant professor in the Department of Crop Sciences at Illinois and co-author on the study, said in a news release.
The study, published in the journal Mycologia, used a field pathogenomics approach to identify the types of FHB on wheat of different resistance levels growing in Brownstown, Carmi, St. Jacob and Savoy.
The method skips several time-consuming steps; traditionally, fungal diseases need to be isolated and grown in the laboratory before genetic material can be extracted and analyzed.
“This tool allows us to monitor almost in real time. It means very fast identification of the pathogen in the field — whether it’s present and what type is there,” Mideros said. “… My goal is to try to produce tools for precision management of plant diseases. To be able to do that, we need to know more about the pathogen.”
Mideros and his research team found only the NA1 variant of the pathogen. And although the pathogen was found on wheat of all resistance levels — susceptible, intermediate and resistant — there were no significant genetic differences among the fungi on the three types.
Finding the NA1 pathogen on intermediate and resistant wheat varieties doesn’t sound good, but Mideros said resistance is working to slow the progression of the disease.
“Resistant varieties might have some disease, but there will be less overall at the end of the season,” he said. “It is good in that aspect. It helps.”
Mideros said his results also show no evidence of an “arms race” between resistant host and pathogen. In many cases, with resistant hosts, pathogens evolve ways to sneak around the resistance mechanism and cause disease. That doesn’t seem to be happening here.
If it were, the research team would have detected changes in key genetic sequences in fungus on the resistant wheat.
That said, the team did find a few small genetic differences in fungus growing on the three resistance types of wheat. So far, the differences don’t seem to add up to an evolutionary benefit for the fungus. Instead, Mideros said researchers could take advantage of these genetic anomalies, using them as targets in future breeding programs.