It’s good to have a thick skin

Researchers at the Canadian Light Source think they have an answer for why some wheat varieties are resistant to fusarium head blight.

The scientists used the synchrotron to examine the structure of the heads of both susceptible and resistant lines of wheat.

“When we did the x-ray analysis of the internal structures we saw striking differences in the junctions where people think the fungus is spread,” said Chithra Karunakaran, manager for the environmental and earth sciences department at the Canadian Light Source.

That junction is where the floret is attached to the main spike of the wheat head.

“We found out there are some structural differences that may play a role against the spread of the fungus in the resistant plant,” she said.

“Some cell walls may be stronger and they have more lignification that may be resistant to the penetration of these fungal micro-organisms.”

The research is expected to help breeders search for the gene responsible for creating thicker cell walls in that area of the plant.

“Talking to people with a plant science background, this is very significant,” said Karunakaran.

Ron DePauw, science adviser to SeCan and retired Agriculture Canada wheat breeder, said the research paints a picture of one possible form of fusarium resistance.

“But you can’t see what genes are needed to combat the pathogen,” he said. “It doesn’t tell you whether you need one gene, two genes or 10 genes.”

DePauw noted that just because one plant seems to have a structural difference that appears to provide some resistance to the devastating fungus doesn’t mean it is a panacea. It may only offer partial resistance to the disease.

“That is a single example of resistance. Are there other ways? Are there other mechanisms? Are there other ways to stop the pathogen?” he said.

“It is part of the puzzle.”

The spread and severity of fusarium infection has been on the rise over the past few years, said Tom Graefenhan, research scientist with the Canadian Grain Commission.

“It’s definitely more prevalent than five or 10 years ago,” he said.

The recent wet weather has helped foster the disease.

“The fusarium situation last year was particularly bad in Saskatchewan for red spring and in Manitoba it was more the winter wheat that was hit badly,” said Graefenhan.

In crop district six in central Saskatchewan 83 percent of the 260 red spring wheat samples submitted to the commission’s harvest sample program had some level of fusarium damage, with an average of 1.9 percent damage.

“It is the worst we have seen for central Saskatchewan by far,” said Graefenhan.

The Canadian Light Source at the University of Saskatchewan uses extremely bright light to study microstructures and chemical properties.

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