Natural Distribution of Incompatibility Factors in Basidiomycetous Fungi

SUMMARY

In earlier studies involving Sistotrema brinkmannii and Schisophyllum commune, it was noted that the frequencies of allelic repeats for incompatibility factors were equal in samples obtained from geographical regions of various sizes. An important exception was noted in S. brinkmannii when the size of the region sampled was that of individual substrates and multiple isolations were made from these individual substrates. These findings prompted a literature search for other fungal species for which there were sufficient data to permit similar analyses. Analyses of data on Schizophyllum commune and Polyporus betulinus confirm these findings of increased frequency of factor-repeats when using multiple isolates from individual substrates. The effects of spore dispersal by wind and the regulation of heterokaryosis exerted by incompatibility factors (particularly through the Buller Phenomenon) are discussed in the context of the observed deviation from random distribution of incompatibility factors in nature.