What lies beneath: WSU team studies soil-borne potato disease with help from NSF, USDA

A team of Washington State University scientists are taking on a destructive complex of diseases affecting valuable potato crops, thanks to support from a joint program of the National Science Foundation and USDA’s National Institute of Food and Agriculture.

The $800,000 project is led by Hanu Pappu, WSU’s Samuel H. Smith Professor and the Chuey Endowed Chair in Plant Pathology, in partnership with plant pathology assistant professor Kiwamu Tanaka and horticulture assistant professor and computational biologist Stephen Ficklin.

Potato mostly covered with brown, scabby blemishes.
A potato infected by powdery scab, a disease caused by a fungus-like microorganism, is covered in unsightly scars.

A disease lurking below ground

Potatoes are a multibillion-dollar industry in Washington State, and Pacific Northwest farmers grow more than 60 percent of the country’s spuds.

Over the last few years, however, Washington’s potato industry has encountered a new threat: Potato mop top virus, a pathogen that lives in soil and attacks the tuber, darkening the flesh and making potatoes unsellable.

A serious problem in Europe for decades, mop top virus was first found in the U.S. in 2002 and discovered in the Pacific Northwest in 2011. It’s been flagged as an emerging disease of importance by Northwest scientists.

Mop top is spread by a protist, a fungus-like microorganism, that causes a disease called powdery scab which blemishes valuable tubers as it infects neighboring plants.

“Unfortunately, powdery scab is present in many fields in our region, and there is no effective control measure” said Pappu. “Together, this disease complex is now even more challenging to manage.”

“What we have now is a peculiar situation: a protist and virus helping each other by attacking and feeding off their common host – potato,” said Tanaka.

Trio of researchers stand in meeting room with WSU Plant Pathology banner in background.
Studying an emerging and destructive complex of diseases in potato, including mop top virus and powdery scab, WSU plant pathologists Kiwamu Tanaka and Hanu Pappu, and computational biologist Stephen Ficklin, right, lead a new federally funded research project (WSU Photo-Seth Truscott).

Knowing your enemy

With the grant, Pappu, Tanaka and Ficklin are using genomics and systems biology tools to gain insights into the cooperative relationship between the protist and the virus, and how the two attack and damage potatoes.

Specifically, Pappu will investigate the molecular basis of potato’s response to virus attack, while Tanaka will use a similar approach to examine potato’s response to the protist. Together, the two will investigate the relationship between the protist and virus.

Ficklin will perform computational genomics and create systems-level models using data generated by Pappu and Tanaka, to help identify additional genes that underlie the disease. He will also expand computational biology tools created through the National Science Foundation’s SciDAS cyberinfrastructure project, with the goal of creating a predictive model in the plant-protist-virus pathosystem.

“The predictive model could be useful for other host-parasite pathosystems causing important diseases,” said Tanaka.

“We’re taking an interdisciplinary approach to study the biology of the players involved in this disease complex,” said Ficklin, “by bringing together both molecular and computational biology approaches.”

“This disease is a serious problem, but scientists don’t currently know much about how to manage it,” said Pappu. “To defeat your enemies, you need to understand them. Thanks to support from USDA-NIFA and the National Science Foundation, we look forward to a better understanding of the three-way interaction between potatoes, powdery scab, and mop top virus, and their common vector. This work could provide new clues to effectively control these diseases.”

Learn more about plant pathology research at the WSU department website.