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UMN News: Putting pathogens in their place


Zhishan Wu
Photo by Martin Moen
Zhishan Wu

The best way to keep highly infectious crop diseases out of Minnesota is to bring them into Minnesota.

Bring them, that is, into the new Plant Pathology Containment Facility on the Twin Cities campus, which soon will quarantine crop-crippling pathogens that haven’t yet arrived in Minnesota on their own. Inside the facility, which opened this week, researchers will study the pathogens and search for ways to manage the diseases they cause.

It’s all about giving researchers and farmers the tools to minimize the impact of pathogens before they arrive or become established in Minnesota or other locations. If licensed next year by the USDA Animal and Plant Health Inspection Service, the facility will open for business under joint operation by the University of Minnesota and the Minnesota Department of Agriculture (MDA).

“We’ve looked forward to this new facility for a long time,” says Zhishan Wu, an MDA scientist and University adjunct assistant professor of emtomology who will be the quarantine officer for the building. “We have a couple of research programs waiting.They will deal with the pathogens Asian soybean rust, sudden oak death, and stem rust.”


The $6 million facility is the only public one of its kind in the Midwest. Three others currently operate in the United States–in Maryland, Florida and Hawaii. Built with funding from the Minnesota Legislature, the University, MDA, and the USDA Forest Service, the plant pathology facility was also championed by state farmers, notably member of the Minnesota Soybean Growers Association.

“This is a perfect example of our land-grant mission to work with different sectors of the economy to enhance our quality of life,” says R. Timothy Mulcahy, the University’s vice president for research. “This is an important first for us with respect to working with diseases that have devastating economic effects on agriculture in the state and the world.”

Playground for pathogens

With more and more land being taken for agriculture worldwide, plus frequent intercontinental travel, our planet is becoming a playground for pathogens. For example, Asian soybean rust, a fungal infection, spread from Asia and Africa across the Atlantic Ocean to South America. Its spores arrived in the southern United States in 2004, blown in from Brazil by hurricanes.

Another reason why centers for studying exotic pathogens are crucial is that evolution is turning some pathogens into greater threats than they used to be.

“Wheat grown in the United States is vulnerable to a new race of stem rust pathogen,” says Carol Ishimaru, head of the University’s Department of Plant Pathology. “The genetic resistance [of wheat plants to rust] has just run out. It had lasted since Norman Borlaug’s work in the 1960s.” Borlaug, a legendary plant breeder and Nobel Peace Prize-winning alumnus of the University, is keenly interested in the work of the facility, she adds.

Worldwide, plant diseases destroy between 9 and 20 percent of crops, Ishimaru says. Much work to defeat the diseases, especially stem rust infections of small grains, involves researchers from around the world because developing countries are hardest hit.

“New sources of resistance genes, in wheat and barley especially, could help farmers from the United States to Kenya,” says Ishimaru.

Where negative is nice

The new building is the final piece of the $24 million Plant Growth Facilities complex on the St. Paul campus. The complex also includes greenhouses and an Insect Quarantine Facility for the study of insect pests and means to control them. The insect facility, which opened in 2003 and holds a slightly lower biosecurity classification than the new building, is connected to the plant pathology facility by a common entrance.

The plant containment facility has several design elements to control the movements of fungi, bacteria, viruses, and other plant pathogens. By entering through the insect facility, researchers will pass through its security and air filtration systems before they get to the higher-security plant pathology building. Once there, they will trade their clothes for disposable duds before entering work spaces.

The work spaces include two greenhouses, an inoculation room for placing pathogenic spores on experimental plants, a very humid “misting room” for germinating the spores, and two growth chambers where lighting and other conditions can be controlled. All these spaces will be subject to negative air pressure to keep pathogens from blowing outside. The air will be circulated through top-quality filters.

When leaving the facility, researchers will shed their disposable clothes and shower before donning their street clothes. Water waste leaving the building will first be heated to 250 degrees to kill any organisms, and trash will go through a high-heat, high-pressure process shared with the insect facility. The basement–a plumber’s paradise of pipes, water tanks, and air ducts–will be accessible through an outside door so that maintenance and service workers can enter without going near the containment areas.

The plant pathology facility, along with its sister research sites, is expected to draw scientists from the University, MDA, the Minnesota Department of Natural Resources, USDA and the USDA Forest Service, as well as from institutions around the world.

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