Method for the production of high proportions of homokaryons in breeding stock of the mushroom agaricus bisporus

The method for determining the presence, in homokaryotic offspring of Agaricus bisporus, of an allele which determines an inherited trait at a first locus, without making test-crosses or performing microscopic examination on mushrooms from crops of descendants of said homokaryotic offspring, said first locus selected from the group consisting of MAT and SNT, and being genetically linked to a second locus, the method comprising the steps of obtaining homokaryotic spores from a parental mushroom;

• germinating said spores on a culture medium;
• isolating each said homokaryotic offspring;
• preparing said homokaryotic offspring for genetic analysis, and determining the genotype of said homokaryotic offspring at the second locus, said second locus being heterozygous and occurring on a segment of Chromosome I which is bounded by the limit of 50 percent recombinational distance from a locus belonging to the group MAT and SNT.

A method for improving the efficiency of gene mapping in Agaricus bisporus by improving the efficiency of obtaining homokaryotic offspring for genetic characterization, comprising the steps of:

• providing homokaryons from a first strain of Agaricus bisporus which produce mushrooms which produce basidia, among which basidia bearing at least three spores predominate;
• crossing said homokaryons from said first strain with at least a second strain of Agaricus bisporus to form at least one hybrid heterokaryotic culture, said at least one hybrid heterokaryotic culture being capable of producing mushrooms, the basidia of which predominantly bear at least three spores, at least 10 percent of said spores being homokaryotic, and isolating homokaryons from said spores.