Morphogenetic Effects of Mutations at the A and B Incompatibility Factors in Coprinus cinereus

Mutated A and B incompatibility factors of Coprinus cinereus (Amut and Bmut) were recovered from fruit bodies produced on common-A and common-B heterokaryons, respectively, following mutagenesis. The Amut hyphal cells were either uninucleate or binucleate and had pseudo-clamps irregularly scattered along the hyphae. The Bmut hyphal cells were predominantly uninucleate and had no clamp structures. Amut Bmut double mutants constructed from these Amut and Bmut strains were predominantly binucleate, had true clamps, and gave rise to fertile fruit bodies indistinguishable from those of wild-type dikaryons. Although these Amut Bmut strains resembled in most respects a normal dikaryon, they produced abundant oidiophores and oidia like the monokaryons. The oidia were uninucleate, and possessed the potential to grow into fertile homokaryons with the above characteristics.