What is Fusarium graminearum, the fungus that 2 Chinese nationals allegedly used to target US food security?
Two Chinese nationals – a woman and her boyfriend – have been charged by the US Department of Justice for allegedly smuggling a dangerous biological pathogen, Fusarium graminearum, into the United States for research at a University of Michigan lab.
Fusarium graminearum was found at a University of Michigan lab after two Chinese nationals allegedly smuggled it into the US, possibly to pose a food security threat. Images of the harmful fungus are now circulating widely on social media.(X)
The Justice Department identified the accused as Yunqing Jian, 33, and Zunyong Liu, 34. They face charges including conspiracy, smuggling goods into the US, providing false statements, and visa fraud.
According to the complaint, Jian received funding from the Chinese government for her research on the pathogen in China. Investigators also found information on her electronic devices indicating her membership in and loyalty to the Chinese Communist Party (CCP).
The complaint further said that Liu, Jian’s boyfriend, is affiliated with a Chinese university where he also studies the same pathogen. Jian initially denied but later admitted to bringing Fusarium graminearum into the US via Detroit Metropolitan Airport to conduct research at the University of Michigan, where she was employed.
What is Fusarium graminearum?
According to ScienceDirect, ‘Fusarium graminearum Schwabe’ is the main pathogen behind Fusarium head blight (FHB) in small cereals and Gibberella ear and stalk rot in maize, particularly in regions like Canada, the US, China, and parts of Europe.
Although it thrives in warm, humid conditions, it can cause widespread crop damage, leading to major yield losses and reduced quality.
The US Department of Justice, in its official release, noted that scientific literature classifies Fusarium graminearum as a potential “agroterrorism” weapon (agroterrorism, also called agriterrorism, is the deliberate use of plant or animal pathogens to damage a population’s agriculture or food supply).
The fungus causes “head blight” in wheat, barley, maize, and rice, contributing to billions in economic losses globally. It also produces toxins that can trigger vomiting, liver damage, and reproductive issues in both humans and livestock.
It triggers billions in crop losses yearly.
Fusarium graminearum infects wheat spikes beginning at anthesis through the soft dough stage of kernel development, and this results in the production of visibly damaged seeds that are chalky white (scabby) and shriveled (tombstones) or symptomless seeds that can also be contaminated with mycotoxins.
In maize, however, infection takes place through silks (near emergence) and wounds in young cobs, and infected kernels usually display a pink to reddish mold. Silks are highly susceptible 2–6 days after emergence; kernels are susceptible until physiological maturity.
How does this fungus enter and affect the plant?
Fusarium graminearum infects plants by entering through natural openings like stomata. After breaching the cuticle, the fungus spreads throughout the plant systemically.
To break down the plant’s structural barriers, F. graminearum relies on a coordinated set of enzymes that degrade the middle lamella and cell walls.
The production of these enzymes, specifically xylanolytic and glucanolytic types, is regulated by a signalling pathway involving Mitogen-Activated Protein Kinase (MAPK). The infection begins with a biotrophic phase, where the fungus feeds on living cells, and then shifts to a necrotrophic phase, likely linked to the production of toxic compounds.
One such toxin is deoxynivalenol (DON), a trichothecene mycotoxin commonly found in infected cereal grains. DON is essential for the fungus to spread, as it disrupts protein synthesis and damages vital cell structures like plasma membranes, chloroplasts, and ribosomes, eventually leading to plant cell death.
During this process, the fungus also neutralises plant toxins and defence proteins, helping it to survive and colonise host tissue.
