Sexual and vegetative incompatibility reactions in Phellinus weirii

Phellinus weirii is a heterothallic basidiomycete lacking clamp connections. Compatible pairings of single-spore isolates have a changed colony morphology, faster growth, and fewer nuclei per cell than the single-spore isolates alone. Compatible pairings occasionally form basidiocarps in culture. Single-spore isolates from different fruiting bodies are sexually compatible; most single-spore isolates from the same fruiting body are incompatible. Vegetative incompatibility is manifested by a line of demarcation formed when two dissimilar heterokaryotic isolates meet. Line formation is a sensitive indicator of genetic differences between heterokaryons or between heterokaryons and homokaryons.