Studies on Cell Number and Nuclei in Spores and on Ploidy Level in Ascochyta rabiei Isolates

Isolates of the phytopathogenic ascomycete Ascochyta rabiei (Pass.) Labr. were stained with the DNA-speci®c ¯uorochrome 4¢,6-diamidino-2-phenylindole (DAPI) and compared for di€erences in number of nuclei per pycnidiospore and the ploidy level. Microscopic analy- ses revealed that within the examined isolates ®ve di€erent combinations of cell number and number of nuclei in spores exist. A one-celled spore may contain one, two and four nuclei, respectively, and in the case of two-celled spores there exist types with one and two nuclei in one cell. Micro¯uorometric analyses of wild types and benomyl-treated isolates revealed di€erences in ploidy level among the wild types.