Data from: Clonal evolution and genome stability in a 2,500-year-old fungal individual

Individuals of the basidiomycete fungus Armillaria are well-known for
their ability to spread from woody substrate to substrate on the forest
floor through the growth of rhizomoprhs. Here we made 248 collections of
A. gallica in one locality in Michigan’s Upper Peninsula. To identify
individuals, we genotyped collections with molecular markers and somatic
compatibility testing. We found several different individuals in proximity
to one another, but one genetic individual stood out as exceptionally
large, covering hundreds of tree root systems over approximate 75 hectares
of forest floor. Based on observed growth rates of the fungus, we estimate
the minimum age of the large individual as 2,500 years. With whole-genome
sequencing and variant discovery, we also found that mutation had occurred
within the somatic cells of the individual, reflecting its historical
pattern of growth from a single point. The overall rate of mutation over
the 90 mb genome, however, was extremely low. This same individual was
first discovered in the late 1980s, but its full spatial extent and
internal mutation dynamic was unkown at that time. The large individual of
A. gallica has been remarkably resistant to genomic change as it has
persisted in place.