Natures wonders: how some fungi survive forest fires (Introduction)

by David Turell , Thursday, April 02, 2020, 19:50 (1694 days ago) @ David Turell

Mainly by hiding out in the tree trunks and popping up after its all over:

https://www.the-scientist.com/notebook/forest-fungi-ride-out-wildfires-by-hiding-inside...

"Toting hard hats and sample collection kits, these scientists jumped at the opportunity to track down their research subjects: pyrophilous (“fire-loving”) fungi, which produce mushrooms prolifically after forest fires and then disappear as the forest recovers.

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"Some fire-loving fungi are known to lie dormant in the dirt as spores or other heat-tolerant structures until post-fire soil conditions trigger growth and reproduction. Other species exist between burns in a vegetative state, aiding decomposition of dead organisms or interacting with tree roots. But many fire-loving fungi don’t fit into any of these categories. A new proposal, known as the body snatchers hypothesis, posits that some pyrophilous fungi hide out inside plants or lichens in between fires, nestling among host cells in a so-called endophytic or endolichenic state.

"To test the hypothesis, the researchers traveled to the burn site every few months for more than a year to sample the soil, as well as the mosses and lichens that sprang up while the forest recovered. They also gathered specimens from unburned areas of the park for comparison. In May 2018, members of Miller’s lab began analyzing the samples they’d collected. DNA sequencing results identified a total of 22 pyrophilous fungal species in the Smokies. Of these, three species were present only in the soil, while the remaining 19 were found inside plant samples from burned and unburned areas, either exclusively or in addition to being found in the soil. In line with the body snatchers hypothesis, “almost all of our pyrophilous fungi were found as endophytes,” Miller says.

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"...it’s still unclear how all of these organisms might persist through a moderate or severe burn, and how a fire-loving fungus would escape its host to recolonize a charred forest. Hughes has a hypothesis based on her observations at the burn site: “After the fire, I saw numerous tiny lichen fragments on the burned soil, as if they had been lofted into the air while trees were burning and settled on the ground after the fire,” she says. These burned plant fragments may inoculate the soil with the fungi they harbor, giving the fire-loving fungi a way into the dirt.

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“'If [a moss fragment] lands in a good place, it can regenerate the whole plant,” says Clay. “If the endophyte is in that fragment, presumably it can just colonize these newly grown plants as well from the get-go.” Post-fire fungi may also acquire new hosts after a burn, Miller notes. One mushroom can produce millions of airborne spores that likely land on nearby mosses and lichens, germinate, and invade the tissues of these new hosts, he says.

"To check whether their findings might apply to other forests, Miller and Hughes analyzed moss and lichen samples from other sites around the US. A handful of the fire-loving fungi identified in the Smokies were also present as endophytes in Indiana and Alaska. That result was surprising because “there was really no evidence that a fire had occurred in the last few years in those areas,” Miller says. “What are they doing there if they’re not waiting for a fire to come along?”

"One possibility is that, while body snatching between fires, pyrophilous fungi use their plant hosts as nutrient sources, says Clay. He notes that many plants and fungi have mutualistic endophytic relationships, where the plant typically provides the fungus with “a home where they can live and sugars, carbon, from photosynthesis.” In return, the fungus often produces alkaloids that benefit the host. Yet for the pyrophilous fungi examined in this study, Clay says, “what they offer the plant is not clear.'”

Comment: The symbiotic relationship with the trees is not known, but the fact that fungi hide out from fires to then reappear to wait for the next fire is obvious. How did this evolve? Fungi not prepared are cooked, so it can't be by trail and error. Only design fits.