Polyploidy in Discomycetes

Polyploidy is quite a common phenomenon in discomycetes. The ploidy levels have been explored by means of microspectrophotometric determination of the relative nuclear DNA content. In rare cases all the examined species of a genus have the same relative DNA contents, i.e. are to be regarded as belonging to one definite ploidy level. Most genera, however, contain species with different ploidy levels. The lowest measured amount of DNA is presumed to represent the haploid state, which is not very common. The most frequent ploidy levels are diploid, triploid, and to some extent also tetraploids. Higher-ploids occur less frequently. Moreover a correlation between grade of ploidy and period of fructification, substrate type and altitude (or climate) has been found. Within the life cycle of a species the relative DNA content of the resting nucleus is constant. Fungal material of the same species but of different origin normally has same DNA values. Some exceptions are described as examples for cryptical speciation.