- Raw data of counts of basidial spore numbers in lamellae of 2 varieties of A. bisporus, i.e. var. bisporus and var. burnettii (parents). The intervarietal hybrid and the intercross of haploid offspring of the intervarietal hybrid. These data sets are used to map QTL of the basidial spore number. - A selection of 71 haploid offspring of HBT03 that was outcrossed with H39. This set was used to generate 40-50 haploid offspring that was subsequently genotyped to assess crossover positions. These data were used to QTL map the trait " recombination landscape" - Genotypes of the intervarietal hybrid HBT03 (var. bisporus H97 x var. burnettii H119p4). 180 homokaryotic single spore isolates (SSIs) were genotyped using 215 SNP's using Kasp genotyping method. - 71 haploid offspring of the intervarietal hybrid HBT03 were outcrossed with the var. bisporis homokaryon H39. From each hybrid, 40-50 haploid offspring was genotyped using 4 SNP markers per chromosome: markers at the chromosome ends, and 2 markers 150-200 kb from chromosome ends ("border" marker).