Evolution and horizontal transfer of the psilocybin biosynthetic gene cluster drive the diversification of magic mushrooms
Mycosphere December 25, 2025 Fei Liu, Jiaxin Li, Wen-Qiang Yang et al. 1 citation
Psilocybin, the psychoactive compound in magic mushrooms, is made by a biosynthetic gene cluster (BGC) once thought unique to Psilocybe species but now found across multiple genera. Sequencing genomes of 30 psilocybin-producing species and comparing them with over 20,000 bacterial, plant, and fungal genomes suggests the BGC originated from endogenous fungal genes through duplication and rearrangement, not from horizontal gene transfer from nonfungal sources. Four independent horizontal transfer events and three BGC configurations were identified. Transcriptomic analysis showed high expression of the PsiK gene in mycelium, while PsiH and PsiM were inactive, matching the absence of psilocybin in mycelial tissue. The BGC's evolution, along with a coprophilous (dung-inhabiting) habit, points to a post-Cretaceous-Tertiary radiation linked to the rise of mammals and grasslands.