Fungi are different from other organisms. They are made of eukaryotic cells, which are also found in plants and animals, but they are not easily grouped in with either of those things, and they are more like animals than plants. There is also no widely accepted way to classify fungi, a huge and diverse kingdom of at least 1.5 million organisms that includes unicellular yeasts, parasites, and mushrooms.
There is a group of about 600 fungi that have little in common with each other than they don't really fit in with other fungal groups, and they have now been shown to share a common ancestor. Genomic techniques revealed the basic similarities underlying these seemingly disparate organisms.
In this work, genetic material was extracted from various fungi and 30 genomes were sequenced. The genetic analysis also revealed that this novel class of fungi has descended over 300 million years from a common ancestor that existed about 240 million years before dinosaurs went extinct. The findings have been reported in Current Biology.
There's no observable feature that shows that they are part of the same group, but the relationships emerge when you look at the genomes, said principal study investigator Toby Spribille, an associate professor in the Department of Biological Sciences at the University of Alberta.
“They were classified, but they were classified into such different parts of the fungal side of the tree of life that people never suspected they were related to each other,” said study co-author David Díaz-Escandón, who also noted that these unusual fungi used to be scattered among seven classes.
These fungi included organisms like lichens from the Atacama desert; earth tongues, which spring up vertically from the ground; or a fungus called beetle gut microbes, which can be found in some tree sap in northern Alberta.
These fungal genomes were small compared to other fungi, which suggests that they need other organisms to survive.
“Their small genomes mean this class of fungi have lost much of their ability to integrate some complex carbohydrates,” explained Spribille. “When we go back to look at each of these fungi, suddenly we see all of them are in a kind of symbiosis.”