How wheat lost the evolutionary battle against its deadly fungal nemesis

July 6, 2017
Wheat blast. Credit: Paul Bachi

A University of Kentucky plant pathologist is part of an international team of researchers who have uncovered an important link to a disease which left unchecked could prove devastating to wheat. UK College of Agriculture, Food and Environment faculty member Mark Farman co-authored an article being published today in Science.

Historically, in Kentucky and across North America has not been susceptible to a recently emerged referred to as wheat blast. However, in 2011, UK researchers discovered a single diseased wheat head in a research plot at the UK Research and Education Center in Princeton, KY. Then, in 2016, a wheat blast epidemic swept through Bangladesh. This year, the disease has again hit Bangladesh and is also present in India, raising the concern that wheat blast may soon become pandemic. The sudden spread of the fungus has prompted intensive global efforts to understand the disease and to breed blast-resistant wheat.

Research in Farman's lab in the UK Department of Plant Pathology revealed that the Kentucky pathogen collected in 2011 is genetically distinct from South American wheat blast and instead is very closely related to strains found on annual ryegrass and tall fescue in the U.S. This suggested that the Princeton incident was not due to introduction of an exotic pathogen but had probably arisen via a 'host jump' from forage grasses to wheat. In contrast, his group found that the 2016 Bangladeshi epidemic very likely arose through the introduction of a South American strain of the fungus.

Microscopic close-up of a wheat blast spore. Credit: Paul Bachi.

Wheat blast is caused by a fungus which infects wheat heads and prevents seed production. At present, there is no natural resistance to the disease in cultivated wheat, and crop losses approaching 100% are common. Fungicides show limited effectiveness due to the development of resistance within the fungus.

"Blast was first identified in Brazil in the 1980's and quickly spread to surrounding countries, including Argentina, Paraguay and Bolivia," said Farman. "Until recently, the disease remained restricted to South America."

Now, with collaborators from Japan and the U.S., Farman has found that the 2011 Kentucky wheat blast strain experienced a mutation in a key gene that codes for a protein that is normally recognized by wheat cultivars that possess a key resistance protein. This mutation is predicted to compromise the function of the 'good' protein, thereby allowing the fungus to escape the wheat resistance response by avoiding recognition. Research performed by Farman's collaborators has established independent mutations in the same gene were likely pivotal events in the emergence of this devastating .

Closeup of mold growing due to wheat blast spores. Credit: Paul Bachi.

"This study provides important insights into the mutational events that underlie the evolution of new crop diseases," said Farman. "This information will help to spur the development of crop varieties with more durable resistance."

Explore further: KSU researchers staying ahead of wheat blast disease

More information: Y. Inoue el al., "Evolution of the wheat blast fungus through functional losses in a host specificity determinant," Science (2017). science.sciencemag.org/cgi/doi … 1126/science.aam9654

Related Stories

KSU researchers staying ahead of wheat blast disease

February 11, 2016

In the past seven years, the U.S. Department of Agriculture has awarded Kansas State University $6.5 million to keep a wheat fungus that has had a devastating impact on wheat production in South America out of the United ...

Developing climate-resilient wheat varieties

May 1, 2017

Increases in climate variability have placed new emphasis on the need for resilient wheat varieties. Alongside demands for increased resiliency, consumer interest in healthier, more functional foods is growing. Therefore, ...

Enhanced wheat curl mite control found in genes

November 9, 2016

The Texas High Plains high winds are known for causing more than just bad hair days; they are a major contributor to the spread of wheat curl mite-transmitted viral diseases in wheat.

Recommended for you

World's smallest tape recorder is built from microbes

November 23, 2017

Through a few clever molecular hacks, researchers at Columbia University Medical Center have converted a natural bacterial immune system into a microscopic data recorder, laying the groundwork for a new class of technologies ...

A possible explanation for how germlines are rejuvenated

November 23, 2017

(Phys.org)—A pair of researchers affiliated with the University of California and Calico Life Sciences, has discovered a possible explanation regarding how human germlines are rejuvenated. In their paper published in the ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

the_bohemian_girl
1 / 5 (3) Jul 07, 2017
I do not see Magnaporthe as a dangerous fungi to humans on the CDC website. Instead of trying to kill this fungus, how about attempting to grow it in multiple various areas instead of the same place it is always grown? If the world's wheat crop fails we can always eat dandelions ;)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.