New research helps resolve evolutionary origins of ‘mushroom platypus’

According to a University of Alberta-led research team that used genome sequencing to give these peculiar creatures their own classification home, around 600 seemingly disparate fungi that never found their way into the tree pedigree of fungi have a common ancestor.

“They don’t have any particular characteristics that you can see with the naked eye where you can tell they belong to the same group. But when you go to the genome, all of a sudden it emerges,” says Toby Spribille, lead researcher at the project. and Associate Professor in the Department of Biological Sciences.

“I like to think of these as the platypus and echidna of the fungal world.”

Spribille, Canada Research Chair in Symbiosis, refers to famous Australian monotremes defying the Linnaean classification system – which produce milk and have nipples, but lay eggs – which have been the subject of debate as to whether they were even real.

“Although no one thought our mushrooms were fake, it’s similar because they all look totally different.”

Using DNA-based dating techniques, the team discovered that this new class of fungi, called Lichinomycetesdescended from the same origin 300 million years ago, or 240 million years before the extinction of the dinosaurs.

David Díaz-Escandón, who carried out the research as part of his doctoral dissertation, explains that these “quirky” fungi were previously divided into seven different classes – a high-level grouping that, in animals, would equate to the groups called mammals. or reptiles.

Working with a team of researchers from seven countries to obtain material from the fungi, he sequenced 30 genomes and found that all but one class descended from a single origin.

“They were classified, but they were classified in such different parts of the fungal side of the tree of life that people never suspected they were related to each other,” says Díaz-Escandón.

These fungi include forms as varied as tongues of earth – strange tongue-shaped mushrooms that shoot vertically out of the ground – gut microbes of beetles and a fungus found in tree sap in northern Alberta. They also include unusual lichens that survive in extreme habitats such as the Atacama Desert in South America, the driest non-polar desert in the world.

“What’s really fascinating is that despite how different these fungi look, they have a lot in common when it comes to their genomes,” says Spribille. “No one saw this coming.”

Based on their genomes, which are small compared to those of other fungi, the team predicts that this group of fungi depends on other organisms for life.

“Their small genomes mean that this class of fungi has lost much of its ability to integrate certain complex carbohydrates,” Spribille said. “When we look back at each of these mushrooms, we suddenly see that they are all in a kind of symbiosis.”

He notes that the new research will be important for the broader study of fungal evolution, particularly how fungi inherit important biotechnological traits such as enzymes that break down plant matter.

The new group could also be a source of new information about past fungal extinctions.

“We think it’s likely that the diversity we see today is just the tip of the iceberg that has survived. And we don’t have many examples of this sort of thing in fungi. “

The research appears online in the journal current biology.

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Materials provided by University of Alberta. Original written by Michael Brown. Note: Content may be edited for style and length.