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Virginia Tech researchers find new way to thwart pathogen that causes sudden oak death

July 17, 2017

Trees are dying due to sudden oak death.
Trees are dying due to sudden oak death. Photo by Yana Valachovic, University of California Cooperative Extension, Humboldt County

Researchers in the Virginia Tech College of Agriculture and Life Sciences are trying to “hack the communication network” of Phytophthora pathogens to stall destructive diseases that have caused significant damage to economies and the environment, including sudden oak death, which has devastated ecosystems in coastal California and Oregon recently, and potato blight that led to Ireland’s Great Famine in the 1840s.

The research team, led by Ping Kong, a research scientist at the Virginia Tech Hampton Roads Agricultural Research and Extension Center, has uncovered one of the strategies that Phytophthora pathogens use to infect plants, pointing to a new way to control these pathogens and stymie the diseases.

They found that Phytophthora zoospores produce, release, and use signal molecules to coordinate their behaviors, including plant infections. Some of these signal molecules are shared with invasive bacteria. Their latest study, with the model plant Arabidopsis, demonstrates that some signal molecules also weaken plant immunity.

This new study, coauthored by John McDowell, a professor in the Department of Plant Pathology, Physiology and Weed Science and the Fralin Life Science Institute, and Chuan Hong, a professor of plant pathology at the Hampton AREC, was recently published in PLOS ONE.

These discoveries are important because current chemical protection approach aiming to destroy the pathogens is not sustainable due to rapid development of fungicide resistance, health, and environmental hazards. The new discoveries provide a horizon for disease control innovation by interrupting the pathogens’ communication signals and network instead of destroying the pathogens themselves. If pathogens can’t “communicate,” infection can be stopped before it even begins.

Phytophthora species cause tens of billions of dollars in damage worldwide every year, and they have demonstrated repeatedly that they can overcome fungicides and our best efforts to breed resistance,” said McDowell. “This study lays the foundation for identifying new signals that the pathogen produces to interfere with the plant immune system. If we can ‘hack this communication network,’ then maybe we can use that information to design more durable fungicides or breeding strategies.”

“The genus Phytophthora has more than 150 members that cause various diseases on a huge number of agriculturally and economically important plants.” said Kong. “The species we have been working on can attack nearly 900 plants, including many vegetables, fruits, and ornamentals.”

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