Nuclear behavior during basidiospore formation in a homothallic mutant of Lentinula edodes

Abstract

Nuclear behavior during basidiospore formation in a homothallic mutant of Lentinula edodes was examined. Light microscopic observations of gill tissues after HC1-Giemsa staining revealed that karyogamy and meiosis were completed normally and sterigmata developed after meiosis. In basidia bearing basidiospore initials, a single post-meiotic mitotic division of the tetrads occurred in each basidiospore. Unsynchronized nuclear migration via sterigma was evident in the binucleate basidium bearing three binucleate basidiospores. Microscopic observations of basidiospores stained with 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) revealed that more than 90% of the basidiospores of wild-type strains were uninucleate, but the mutant produced basidiospores carrying an irregular number of nuclei; about half of the basidiospores were DAPI-negative, about 30% were uninucleate and approximately 10% were binucleate. Electron microscopic observation of prophase I nucleus revealed the existence of typical synaptonemal complexes composed of three elements.