Kerrigan R W, Royer J C, Baller L M, Kohli Y, Horgen P A, Anderson J B
Department of Botany, Erindale College, University of Toronto, Mississauga, Ontario, Canada.
Genetics. 1993 Feb;133(2):225-36. doi: 10.1093/genetics/133.2.225.
This study followed the transmission of 64 segregating genetic markers to 52 haploid offspring, obtained from both homokaryotic and heterokaryotic meiospores, of a cross (AG 93b) of Agaricus bisporus, the commonly cultivated "button mushroom." The electrophoretic karyotypes of the AG 93b component nuclei were determined concurrently (n = 13). Eleven distinct linkage groups were identified by two-point analysis. DNA-DNA hybridization showed that nine of these corresponded to unique chromosome-sized DNAs. Two other chromosomal DNAs were marked with nonsegregating markers, including the rDNA repeat. Two remaining chromosomes remained unmarked but hybridized to repeated-sequence probes. Cross 93b had an essentially conventional meiosis in which both independent assortment and joint segregation of markers occurred, but in which crossing over was infrequent over much of the mapped genome. The 48 homokaryotic spore-offspring had overall crossover frequencies that were similar to, but possibly slightly less than, those of three homokaryon constituents of heterokaryotic spore-offspring. These daa provide support for our earlier cytogenetic model of sporogenesis in A. bisporus, that explains why heterokaryotic spore-offspring usually appear to exhibit no recombination. No evidence favoring an alternative, mitotic model of sporogenesis was found. The resulting genetic map appears to survey the genome extensively and for the first time permits localization of loci determining economically important traits in this fungal crop species. Large differences in the vigor of homokaryotic offspring were correlated with the inheritance of certain chromosome segments and were also often associated with significant departures from Mendelian segregation ratios.
本研究追踪了64个分离的遗传标记向52个单倍体后代的传递情况，这些后代来自双孢蘑菇（即常见的栽培“纽扣蘑菇”）的一个杂交组合（AG 93b）的同核和异核减数孢子。同时测定了AG 93b组成细胞核的电泳核型（n = 13）。通过两点分析确定了11个不同的连锁群。DNA-DNA杂交表明，其中9个对应于独特的染色体大小的DNA。另外两个染色体DNA用非分离标记进行了标记，包括rDNA重复序列。其余两条染色体未被标记，但与重复序列探针杂交。杂交组合93b具有基本常规的减数分裂，其中标记既有独立分配又有联合分离，但在大部分已绘制图谱的基因组中很少发生交叉。48个同核孢子后代的总体交叉频率与异核孢子后代的三个同核体成分的交叉频率相似，但可能略低。这些数据支持了我们早期关于双孢蘑菇孢子发生的细胞遗传学模型，该模型解释了为什么异核孢子后代通常似乎没有重组现象。未发现支持另一种有丝分裂孢子发生模型的证据。由此产生的遗传图谱似乎广泛地勘测了基因组，并且首次允许定位决定这种真菌作物物种中经济上重要性状的基因座。同核后代活力的巨大差异与某些染色体片段的遗传相关，并且也常常与显著偏离孟德尔分离比有关。
