Snowball (snb): A Novel Conserved Gene Family Involved In The Fruiting Body Development Of Agaricomycetes

Snowball (snb): A Novel Conserved Gene Family Involved In The Fruiting Body Development Of Agaricomycetes

Csenge Földi1*, Zsolt Merényi1, László Galgóczy1,2 and László G. Nagy1

1Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre, Szeged, 6726, Hungary

2Department of Biotechnology, Faculty of Science and Informatics, University of Szeged, Szeged 6726, Hungary

*Email: foldi.csenge@brc.hu

The fruiting body morphogenesis is a complex process determined by a genetically encoded programme that has reached its highest complexity in agaricomycetes. Most of the conserved developmentally regulated genes in this class are functionally poorly characterised or unannotated, meaning that they encode proteins without known domains. In the present work, we functionally characterised an unannotated gene provisionally called  snb1, whose expression level increases by two orders of magnitude during fruiting body initiation compared to vegetative mycelium. According to our phylogenetic analysis, orthologues of snb1 are present in almost all complex multicellular agaricomycetes. We disrupted snb1 using the CRISPR/Cas9 system in the basidiomycete model organism Coprinopsis cinerea. Snb1 mutants formed snowball-shaped, spherical and rudimentary fruiting bodies that lacked stipes and lamellae. In constant darkness, these mutants failed to develop dark stipes, indicating the inactivity of nodulus elongation mechanisms. Using RNA-Seq analyses, we compared the initial stages of fruiting in both the wild type and the snb1 mutant, revealing a multitude of differentially regulated genes and gene families, including unannotated or poorly characterised ones, that may have a major influence on tissue differentiation and the formation of complex multicellular structures. Taken together, the identification of differentially regulated genes in the snb1 mutants provides valuable insights into the complex mechanisms underlying tissue differentiation that require further research. Additionally, snb1 may be part of a novel conserved gene family that plays a substantial role in establishing fruiting body in agaricomycetes.