Developmental genetics of Coprinus cinereus: Genetic evidence that carpophores and sclerotia share a common pathway of initiation.

Five haploid monokaryons of the basidiomycete Coprinus cinereus were already known to be unable to form sclerotia (asexual resting structures) on the vegetative monokaryotic mycelium. Genetic analyses had shown that four distinct genes (symbolised scl were represented, all being "recessive" to their sclerotium-producing alleles. In the study reported, homoallelic dikaryons were constructed and the effect of the sclerotium-negative genes on carpophore formation investigated. In the homoallelic state these defective genes prevent the formation of both sclerotia and carpophores by the dikaryon. Thereby demonstrating that these two structures share a common pathway of initiation. It is also shown that the expression of effects of scl genes on carpophore maturation in heteroallelic dikaryons is subject to the influence of modifying genes. Possible modes of action of modifying genes and of the scl genes are discussed and a carpophore developmental pathway is presented.