Mutagenesis of Protoplasts and Regeneration of Mycelium in the Mushroom Volvariella volvacea.

Regenerating protoplasts were obtained from mycelial culture of the mushroom Volvariella volvacea by the action of the lytic enzyme Novozym 234 in the presence of 0.01 M phosphate buffer (pH 6.0) containing 0.6 M NaCl. Regeneration was found to be poor in liquid medium, but more than 50% regeneration was achieved on solid 2% agar medium overlaid with 0.5% agar. Protoplasts of V. volvacea were found to be highly sensitive to the killing action of both UV irradiation and N-methyl-N'-nitro-N-nitrosoguanidine. However, no morphological or auxotrophic mutants could be obtained from protoplasts by chemical mutagenesis. Four types of morphological mutants and one auxotrophic (adenine-negative) mutant were obtained from UV-irradiated protoplasts. The adenine-negative mutant of V. volvacea was found to be stable, not losing auxotrophy on repeated subculture.