This 200-Acre, ‘Humungous Fungus’ May Help Unravel Why Cancer Genes Are Unstable

By Roni Dengler | December 18, 2018 6:01 pm
the individual mushrooms of  Armillaria

The individual mushrooms on this 200-acre fungus only live a few weeks, but the organism itself has been around for some 2,500 years, scientists think. (Credit: Johann Bruhn)

In the mid-’80s, scientists discovered a giant fungus growing in Michigan’s Upper Peninsula. Now, researchers have found the organism is at least 2,500 years old. And the secret to the mushroom’s longevity might be a genome that’s highly resistant to mutation, the team reports today in the journal Proceedings of the Royal Society B. The discovery could help researchers figure out why cancer genomes are so unstable.

Forest Recycler

In 1983, Johann Bruhn planted red pines in the forest. Within the next few years, the trees began to die. The trend continued for about 15 years. Bruhn, a forest health specialist at the University of Missouri in Columbia, traced the trees’ deaths to a species of honey mushroom dubbed Armillaria gallica, a parasitic fungus that preys on trees weakened by drought, insects and other fungal infections. Bruhn examined the fungus, taking it out of the forest to find out whether a unique clone was responsible for the deaths. That’s when he stumbled on something unexpected.

“It looked like one of these clones … extended off into the forest,” Bruhn said. “We didn’t know how far.”

So he and a team of researchers collected more fungus samples further and further afield. By 1992, the researchers knew the fungus was big. They estimated its mass (about 11 tons) and age (at least 1,500 years-old) and reported their findings in a scientific journal.

But the team hadn’t reached the edge of what became known as the “humongous fungus.” That only happened in the last few years. Now, Bruhn and colleagues estimate the fungus is about 1,000 years older and four times bigger than they previously thought.

mushroom clone sample

An isolated sample of the “humungous fungus” clone. (Credit: Johann Bruhn)

Cancer Contrast

The discovery begged the question: How did it survive for so long and get so big? The researchers suspected that the fungus must be incredibly stable genetically. So the team sequenced the organism’s genome from collected samples.

“It turned out that this fungus, this clone of Armillaria gallica, has an extremely low rate of mutation,” Bruhn said. The find is especially surprising given the fungus is so large. Bruhn and colleagues estimate it spreads through nearly 190 acres of the forest floor.

The individual mushrooms themselves last just a few weeks, but the clone itself, as identified by its genetic code, persists. Bruhn compares it to a redwood tree, where the most ancient wood cells are long-dead. “The defining feature of an individual is its unique genetic code that defines the rule set for its continued existence,” he said. “In this sense, the cell lineage of the humungous fungus dates back to a single sexual mating event roughly 2,500 years ago that defines its way of life.”

And, perhaps most intriguingly, the stability of the mushroom’s genome stands in stark to contrast to cancers, which have radically unstable genetic material.

“Our A. gallica must be at the opposite extreme as cancer,” Bruhn said. The fungus’ mutation rate is “a counterpoint to cancer mutation.”

“It could be an interesting point of comparison,” James Anderson, a population geneticist who co-led the new work with Bruhn, said in a statement. “Cancer is so unstable, mutates at a high rate and is prone to genomic changes, while A. gallica is a very persistent organism with few mutations.”

CATEGORIZED UNDER: Living World, top posts
  • Rose

    the fungus DNA was set by GOD during Creation and hasn’t altered.
    Cancers were all cooked up by Satan and just like his Nephilim children the grow wildly unstable and deadly.

    • Erik Bosma

      This sounds like an opinion.

      • Mike Richardson

        That’s being charitable.

        • Rose

          that sounds like the opinion of someone named Mike who evolved from monkeys that evolved from fish…

          • Mike Richardson

            Whether or not you choose to believe it, all humans are evolved from earlier forms of primates. And yes, those primates, like all land vertebrates, evolved from creatures that evolved from fish. If you don’t accept that basic premise, you really shouldn’t be posting your own opinions here, since they are directly contradicted by the research discussed in these blogs — as well as evolutionary biology going back to the mid-19th century.

          • Holly Lugene Parrish

            Oh my. It sounds as if you are an educated man. Hypochristians hate that!!!

      • Rose

        that sounds like to opinion of someone who evolved from monkeys that evolved from fish…

      • Rose

        Opinion = education and knowledge.
        Hard for people evolved from monkeys to understand this.

  • justawriter

    Just a note to those who cast an editorial glance at the postings of the writers here. This is the second post on the front page to use “begs the question” instead of “raises the question”. Begging the question is a logical fallacy that carries a presumption without providing evidence. “Have you stopped beating your wife” (without showing that said wife was ever beaten) is the canonical expression of begging the question. I know that usage determines definitions in the long run, but I mourn the loss of such a powerful descriptive phrase from our vocabulary.


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