ELECTROPHORETIC KARYOTYPE ANALYSIS OF THE BUTTON MUSHROOM, AGARICUS-BISPORUS

An efficient procedure is presented for the generation of protoplasts from shake flask cultures of the commercial mushroom Agaricus bisporus. Orthogonal field electrophoresis (OFAGE) of high molecular weight DNA from lysed protoplasts resolved the genome of A. bisporus into at least 10 bands, ranging in size from 1.2 to 4 Mb. The illustrated electrophoretic karyotypes of two homokaryons were highly polymorphic. A heterokaryon of the two homokaryons contained a mixture of the two electrophoretic patterns, though the ratio of nuclear types was not equal. A number of RFLP and RAPD markers and the rDNA repeat have been localized to specific chromosomes. Based on ethidium bromide staining intensity and autoradiography, we have estimated the chromosome number of A. bisporus to be 13.