What is Fusarium graminearum, the fungus US authorities say was smuggled in from China?

Two Chinese researchers faced federal charges on Tuesday for allegedly smuggling a destructive fungus into the U.S. last summer, amidst increasing political strain between the nations and the Trump administration's efforts to cancel visas of Chinese students.

The accused, Yunqing Jian and Zunyong Liu, face multiple charges including conspiracy, smuggling, false statements and visa fraud for importing Fusarium graminearum. Jian, 33, appeared in a Detroit federal court, whilst Liu, 34, is believed to be in China.

FBI reports indicate Liu transported small bags of the fungus in his backpack during his U.S. flight last year. After initially denying knowledge of the contents, he stated his intention to use it for research at a University of Michigan laboratory where both he and Jian had worked.

Fusarium graminearum induces Fusarium head blight, a disease devastating to cereal crops including wheat, barley, maize and rice. The U.S. Department of Agriculture reports annual losses of $1 billion in wheat and barley crops due to this disease.

This fungus, whilst not unique in causing Fusarium head blight, is the predominant source in the U.S. It affects plants early in growth, causing wheat grain shrinkage and white-tan discolouration of crop heads. It produces a toxin in wheat kernels harmful to both humans and livestock.

"Vomitoxin", its common name, causes vomiting in livestock and can trigger diarrhea, abdominal pain, headache and fever in both animals and humans.

Grain crops undergo screening for various toxins, including Fusarium graminearum, before consumption. Infected grains require disposal, resulting in significant agricultural losses.

"It's one of the many problems that farmers have to deal with that risks their livelihood," said David Geiser, a Fusarium expert at Penn State.

Despite the smuggling charges, Fusarium graminearum already exists in the U.S., particularly in eastern regions and the Upper Midwest, where scientists have studied it extensively.

Whilst researchers regularly import foreign organisms for study, proper permits are required for cross-border transportation. Studying foreign fungus strains' genes helps understand their heat tolerance, pesticide resistance and mutations.

"We look at variations among individuals just like we do humans," said Nicole Gauthier, a plant pathologist at the University of Kentucky who studies Fusarium.

The motivations behind the researchers' actions and their failure to obtain proper documentation remain unclear.

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