MONOKARYOTIC FRUITING OF PLEUROTUS-OSTREA TUS

Monokaryotic fruiting was observed in mycelia regenerated from protopl asts which were released from dikaryotic mycelium of Pleurotus ostreat us (jacq.: Fr.) Kummer. Thirteen of forty-five regenerants obtained at random were monokaryons as the result of observations of clamp connec tions in the hyphae and nuclear staining with HCl-Giemsa. Fruiting bod y formation was observed in eleven of the thirteen monokaryotic regene rants. The average weights of fruiting bodies formed by the monokaryon s were about 65% of those formed by the parents. Twenty more days were needed to form the fruiting bodies in comparison with those of the pa rents. However, dikaryotization using the thirteen monokaryotic regene rants was not performed with every combination. Therefore, nuclei in a ll monokaryotic regenerants were derived from only one side of the nuc lei in a cell of the parental dikaryon. Furthermore, the mating type o f the monokaryons regenerated from basidiospores of the monokaryotic f ruiting bodies was revealed to be tetrapolar as well as in those of pa rental dikaryon from the result of mating with all combination. This f act indicated that the segregation of hereditary characters, such as m ating type factor, arose in the basidiospores of monokaryotic fruiting bodies.