Since sexual crosses are unavailable in these species, the parasexual analysis, apart from physical mapping, is the only way of mapping the chromosomes. The use of the parasexual cycle requires a method to distinguish between haploids and diploids. Here, we report the use of flow-cytometry to distinguish clearly between haploid and diploid strains of Aspergillus fumigatus , a very rapid, simple and accurate technique that can be applied to parasexual analysis in other filamentous fungi. For accurate deductions of the parasexual analysis a reliable method is required in order to distinguish among them. However, in other filamentous fungi lacking these recognition systems, such as the pathogenic fungus Aspergillus fumigatus , the major criterion for distinguishing ploidy is the spore diameter.
Diploid strains have larger asexual spores because of the increase in nuclear volume.
We have found it extremely difficult to distinguish between the diameter of spores of diploid and haploid strains in A. fumigatus, especially since differences among diameters of haploid or diploid spores are commonly observed by microscopy. In addition, the method devised by Upshall et al . Diploid strains of this fungus were not much more sensitive to benlate or benomyl than haploids, possibly because of the high growth rate of A. fumigatus compared with other Aspergillus species. Shappiro 1993 Ann. Here we report the use of flow-cytometry to distinguish clearly between haploid and diploid strains of A. fumigatus by their differences in DNA content.