Iin a large greenhouse at the University KansasProfessor Liz Koziol and Dr Terra Lubin tend rows of Sudan grass in individual plastic pots. The roots of each scattered plant harbor a special strain of invisible soil fungus. The shelves of a nearby refrigerated room are lined with thousands of plastic bags and vials containing fungal spores collected from these plants and then carefully preserved by researchers.
The specimens in this seemingly unremarkable room are part of the International Vesicular-Arbuscular Mycorrhiza Collection. Mushrooms (INVAM), the world's largest living library of soil fungi. Four decades in the making, it could cease to exist within a year due to federal budget cuts.
For leading mycologist Toby Kearse, this would have been disastrous. “INVAM represents a library of hundreds of millions of years of evolution,” said Kearse, executive director of the Underground Networks Protection Society (Spun). “Canceling INVAM for scientists is like closing the Louvre for artists.”
Arbuscular mycorrhizal (AM) fungi, conserved by INVAM, are symbiotic organisms that support the growth of 70% of land plant species across all ecosystems. In exchange for sugars and fats, they provide plants with vital nutrients – phosphorus, nitrogen, trace elements – and protect them from drought, disease and other stressors. They also represent a significant underground sink for carbon dioxide.
INVAM stores live spores of over 900 different strains of mushrooms collected from six continents. It's an indispensable center for mycological research around the world, but these fungi also have practical powers: restoring degraded ecosystems, restoring damaged soils and reducing the use of artificial fertilizers. They are important tools for growing food and eliminating environmental damage caused by agriculture.
Founded in 1985, INVAM has relied on successive federal grants throughout its existence. The latest funding from the US National Science Foundation (NSF) ended in May. As curator and professor Jim Bever and his team prepare a new funding proposal, the outlook is ominous: the Trump administration proposed budget for fiscal year 2026 would cut NSF funding by 57% and make it even more difficult to obtain remaining funds.
Without another grant, Bever estimates the collection could survive for another year. In addition, INVAM may be forced to close. “It’s hard for me to think about that possibility,” Bever said, “but we can’t deny that it’s true.” For now, INVAM survives on temporary research grants and volunteer labor. Unlike the collection's previous location at West Virginia University, which provided institutional support for staff, the University of Kansas covers infrastructure and overhead costs, but not personnel.
And the staff is critical. Unlike seeds stored in storage or cages, frozen indefinitely, without constant and painstaking work, AM fungal spores die. At INVAM, Assistant Curator Lubin works under a microscope to isolate and identify AM spores from intact soil. When viewed under a microscope, these spores look amazing: shiny balls filled with nutrients necessary to support young mushrooms.
Lubin then paints isolated spores on the roots of sudangrass seedlings. These host plants will grow in a sterile greenhouse for 12 weeks while the fungi colonize their roots and soil. The plants will then lack water, prompting the fungus to produce millions of spores, which workers collect and store in a nearby cold room. For each of INVAM's more than 900 strains, this process must be repeated annually.
“Isolating and maintaining AM fungi requires a mysterious set of skills,” Bever said. “There’s really no other lab in the United States that does this.”
Most commercial biofertilizers are 'really terrible'
INVAM prepares small batches of AM fungal spores for distribution or sale to other researchers and land managers. But Bever makes it clear that this is not a commercial operation and INVAM has neither the capacity nor the ambition to expand production. This is important because the commercial market for AM mushrooms is rife with problems.
IN 2024 studyBever and his colleagues tested 23 products marketed as fungal biofertilizers—AM spores—that claim to naturally stimulate plant growth. Eighty-seven percent were unable to colonize plant roots. Many contained only dead spores or no spores at all. Some products contained known plant pathogens. Large-scale 2022 study European researchers have identified similar shortcomings. Bever and Koziol 2024 meta-analysis Global studies have reached the same alarming conclusion: most commercial AM fertilizers are useless.
“Unfortunately, the quality of most of the products available to farmers and regenerators is really terrible,” Bever said.
However, landowners buy them. World market of fungal biofertilizers worth $1.29 billion.. Much of this money is wasted on products that simply don't work. Bever sees two key problems: the industry lacks regulation, and most producers lack the specialized expertise needed to effectively manage and distribute these delicate organisms. Meanwhile, the government's research infrastructure, which could offer real solutions, is struggling to survive.
But high-quality biofertilizers can be priceless
The failure of most commercial biofertilizers stands in stark contrast to the research demonstrating what these organisms can actually achieve.
At a field study site near the INVAM facility in Lawrence, Kansas, the influence of invisible fungi is evident. Nine years ago it was an old, tired hay field, overgrown with aggressive grass. Today it is a riot of colors and diversity. Twelve-foot prairie docks rise above head-high grass; grasshoppers hop and butterflies flutter between the late-blooming flowers, even in October. This small area is a reincarnation of the tallgrass prairie that once dominated the central United States. It was this ecosystem that created the deep, fertile soils that made the area such a prime target for conversion to farmland—a shift that turned the prairie into mere desert. 1-4% of original size.
AM mushrooms led to transformation. In 2016, INVAM curator Koziol seeded the plots with dozens of native prairie plants, as well as AM spores from surviving fragments of old prairie. Control plots produced seeds but not mushrooms. As a result, dozens of plants in the control plots did not take root, and all plants grew slowly. Nine years later, the difference between control plots and AM-treated plots is still evident.
Modern agriculture is eradicating AM fungi, which is why reintroducing them can produce such dramatic results. Fungicides used to control plant diseases penetrate the soil, killing AM fungi. Excessive application of synthetic fertilizers leads to the severing of symbiotic relationships between plants and the death of fungi. Plowing destroys their underground networks. As a result, AM fungi often disappear completely from cultivated lands: “We can barely even find DNA [of AM fungi] in some soils that have been subject to intensive agricultural production,” said leading fungal ecologist Matthias Rillig of the Free University of Berlin.
This is important because AM fungi spread slowly—they do not produce above-ground fruiting bodies that can carry spores to the wind. As a result, reintroduction is often necessary for recovery.
Based on their successful experiments in prairie restoration, Bever and Koziol see the potential of AM fungi to create prairie stripes – patches of deep-rooted, species-rich perennial plants in existing agricultural fields that promote pollinator abundance and limit the runoff of fertilizers that pollute groundwater and create dead zones in waterways.
“The prairie strips are amazing,” Bever said, but he believes there is more potential in the sanctuary program. This federal scheme is already enrolled over 20m acressupporting landowners to convert marginal farmland into natural grasslands and forests to improve soil health, water and carbon conservation. “The return on this investment would be much higher if there were a national policy to reinoculate with native mycorrhizal fungi,” he said.
In addition to habitat restoration, and despite the current ineffectiveness of most commercial fungal biofertilizers, AM fungi may be useful in conventional agriculture. In 2016 Koziol founded MikoBloom produce high-quality preparations of spores of old-growth steppe mushrooms. In addition to restoration specialists, customers are reporting encouraging results in vineyards, orange orchards and high-value organic crops such as peppers and tomatoes.
The impact of AM fungi is likely to be greatest on perennial crops, including new grain crops such as Kernzawhose roots remain in the ground long enough to establish a stable symbiosis. But evidence suggests that AM fungi can also boost annual food production. for example corn.
“The benefits of mycorrhizal fungi are real,” Bever said. However, scientists are just beginning to understand how these organisms work. Numerous research questions regarding AM fungi can only be answered with the help of living libraries such as INVAM, Bever added. Why, for example, do the cells of AM fungi contain thousands of nuclei, while ours only need one? And how can seemingly different species combine their cells to create hybrids? “Research on mycorrhizal fungi depends entirely on the presence of these fungi in culture,” Bever said.
“The current administration has moved funding away from basic science,” he added, “and while there is always hope that private donors can fill that gap, I don’t think there is a realistic replacement for federal investment.”
Kearse, now a professor at the Vrije Universiteit Amsterdam, described how visiting INVAM in the 1990s to identify spores collected from the extremely diverse rainforests of Panama influenced her entire career: “After I saw that collection, I was hooked. It changed the way I looked at the underground.
“To have any hope of using fungi for future climate change strategies, restoration efforts and regenerative agriculture, we need to preserve this collection,” Kearse said.
Merlin Sheldrake, mycologist and author of Entangled Lives: How Fungi Shape Our Worlds, Change Our Minds, and Shape Our Futures, strongly agreed.
“These organisms are vital ecosystem engineers that hold the key to solving many of the problems we face,” he said. “To lose this library would be an unimaginable tragedy.”
