04.2020 | THE SCIENTIST 13dead 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 pyroph-
ilous 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 analyz-
ing 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.
Mosses and lichens often live in
difficult-to-reach places such as rock
crevices and may be hardy enough to
withstand minor flames, so fungi living
inside these hosts could theoretically sur-
vive a low-intensity wildfire. But 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 for-
est. Hughes has a hypothesis based on
her observations at the burn site: “After
the fire, I saw numerous tiny lichen frag-
ments on the burned soil, as if they had
been lofted into the air while trees wereburning 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.
This is a feasible way for both a
pyrophilous fungus and its host to
rebound after a fire and maintain their
relationship, according to Keith C l ay,
who studies plant-fungus interactions at
Tulane University and was not involved
with this study. “If [a moss fragment]
lands in a good place, it can regenerate
the whole plant,” says C l ay. “If the endo-
phyte 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 snatch-
ing between fires, pyrophilous fungi use their
plant hosts as nutrient sources, says C l ay.
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, car-
bon, from photosynthesis.” In return, the fun-The level of destruction
was incredible. Everything
I touched left black carbon
on my hands.
—Karen Hughes
University of Tennessee, KnoxvilleBOUNCING BACK: Pyrophilous fungi such as
Geopyxis carbonaria start producing mushrooms
following fires.DANIEL RAUDABAUGH