Magic mushrooms are fungi that produce psilocybin, a compound with
breakthrough status for treatment of mental health disorders.
Wood-degrading species of Psilocybe, such as P.
subaeruginosa and relatives, have high concentrations of psilocybin but
are discouraged for clinical production due to a temporary paralytic
side effect known as Wood Lover’s Paralysis, the cause of which is
unknown. We studied P. subaeruginosa over its partial
distribution in Australia based on genomic analyses of 89 isolates to
investigate population structure and species boundaries, examine allelic
diversity at psilocybin loci, and test its centre of origin.
Psilocybe subaeruginosa is structured by geography in Australia,
but geographically separated populations are fully sexually compatible.
Allelic diversity among populations, such as at mating compatibility
loci, is likely a result of genetic drift and minimal gene flow since
differentiation from a shared ancestor. Movement of woodchips, mulch, or
plants has most likely spread genotypes of P. subaeruginosa
locally within Australia and to the northern hemisphere. Species from
the northern hemisphere, namely P. azurescens and P.
cyanescens, clustered among Australian populations, indicating shared
ancestry and supporting a hypothesis these taxa are conspecific with
P. subaeruginosa. We identified high allelic diversity in genes
of the psilocybin metabolic pathway and haplotypes of P.
subaeruginosa with either one or two putatively functional paralogs of
psiH, however the functionality of this gene duplication is yet
to be determined. Our study provides insights into the evolutionary
history and species boundaries of P. subaeruginosa, which has a
centre of origin in Australasia.