Fungus helps park grass survive high temperatures
Photo by R. Stout, courtesy Montana State University Hot springs panic grass can tolerate soil temperatures of 115 degrees Fahrenheit (46.5 Celsius) or higher in Yellowstone National Park. Scientists recently uncovered the relationship between the plant and a fungus that allows both to survive in high heat.

Everyone needs a friend, especially when you're trying to eke out a living in some of the harshest environments in Yellowstone National Park.

Hot springs panic grass, which grows throughout the park's geyser basins where soil temperatures can reach 140 degrees, is no different.

In this case, the friend is a tiny stringy fungus that lives between the plant's cells.

The fungus, called curvularia, helps hot spring panic grass survive the high temperatures - and the plant does the same for the fungus, according to new research from Montana State University and the University of Washington.

The scientists published their findings recently in the journal Science.

Mutually beneficial relationships between plants and fungi are nothing new and may date back 500 million years to the time when plants first started to evolve.

What botanists are excited about in the new Yellowstone research is that that the microscopic fungus isn't just helping to gather food and water, it's making sure the plant can withstand the soil's high heat.

"As far as we know, this is the first report of heat tolerance conferred by fungal involvement," said Rich Stout, an MSU plant scientists and a co-author of the study. "The question is why, and that's what we're working on now."

Researchers studied samples of the grass from Yellowstone and Lassen Volcanic National Park. They also grew specimens in a laboratory with and without the fungus and then heated up the soil.

They found that the plants with the fungus survived temperatures as high as 149 degrees. Plants without the fungus shriveled at 122 degrees.

More experiments showed that the plant provided thermal protection for the fungus, too.

In fact, neither the plant nor the fungus could live without the other in Yellowstone's hot soil, Stout said.

Researchers are still trying to understand how the plant and the fungus help each other, but they think it might start as soon as a fungal spore in the air latches onto the plant.

"We think that when they do this cellular handshake, when they recognize each other, that perhaps genes are activated in the fungus in the plant," Stout said.

That interaction could be waking up dormant "heat shock" genes, biological triggers that tell the plant to get ready to protect itself from high temperatures.

"It may put them on alert," Stout said. "So when stress comes along, it's sort of like Boy Scouts, be prepared."

Researchers plan to analyze the genetic codes of the plant and the fungus and then try to figure out which genes are "switched on" when the two come together.

Yellowstone researchers are always eager to learn something more about how plants and animals survive in and around geothermal features. There's also a possibility that the new information could have commercial applications.

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Stout theorized that if they can understand how the fungus helps the plant live in the heat, maybe there's a way to apply that to wheat, barley or other crops that struggle in hot, dry summers.

"But that's science fiction at this point," Stout said.

The research was funded in part by MSU's Thermal Biology Institute and the National Science Foundation's Microbial Observatories Program.

Matt Kane, director of the NSF's microbial observatories, said there is national interest in finding out more about how species, particularly tiny microbes, survive in Yellowstone's unique habitats.

"The features within the park present such an incredible diversity of habitats for different micro-organisms," Kane said. "It's really probably one of the most wonderful places to study microbial diversity in the world."

The program, which began four years ago, has 35 projects under way in the United States and elsewhere. But Yellowstone is the only place where four observatories have been set up to examine microscopic life.

Understanding the mysteries of tiny organisms in Yellowstone and other geothermic areas has been gaining steam the last few years, partly because new discoveries could have applications elsewhere in the world, such as antibiotics or new materials.

Researchers figure that 99 percent of microbes are still unknown to scientists, Kane said. Yellowstone, with its vast and varying terrain, is one of the best places to unlock those secrets, he said.

"From a microbial point of view, there are all these different universes in one place," Kane said. "It's like having a rain forest next to a coral reef."

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