Class | Genotype of disome | Maters (%)^{a} | Nonmaters (%)^{b} |
---|---|---|---|

A | Het. iTHR1 Het. iNAT (parental configuration)^{c} | 14 (24) | NA |

B | Het. iTHR1 Het. iNAT (nonparental configuration)^{d} | 20 (34) | NA |

C | Het. iTHR1 Het. iNAT (configuration unknown)^{e} | NA | 38 (59) |

D | Hom. iTHR1 Het. iNAT^{f} | 14 (24) | 10 (15) |

E | Het. iTHR1 Hom. iNAT^{f} | 9 (16) | 15 (23) |

F | Hom. iTHR1 Hom. iNAT^{g} | 1 (2) | 2 (3) |

% CO frequency | 74^{h} | >38 (72^{i})^{j} |

Disomic Ura

^{+}gene convertants selected from spores of BR4633 were analyzed for crossing over in the*iTHR1-iNAT*interval. Het., heterozygous; Hom., homozygous; NA, not applicable.↵

*a*A total of 58 mating-competent disomes were scored by tetrad analysis.↵

*b*A total of 65 nonmating disomes were analyzed by PCR.↵

*c*The two chromatids retained the parental configuration of markers. One carried*iTHR1*, but not*iNAT*; the other carried*iNAT*, but not*iTHR1*.↵

*d*Both chromatids displayed a recombinant configuration of markers. One carried both*iTHR1*and*iNAT*; the other chromatid carried neither marker.↵

*e*Classes A and B cannot be distinguished by PCR analysis.↵

*f*These classes result from crossing over in the*iTHR1–iNAT*interval.↵

*g*This class represents MII disomes carrying sister chromatids.↵

*h*CO frequency was calculated as the sum of classes B, D, and E divided by the sum of all classes and multiplied by 100.↵

*i*CO frequency represents the minimum frequency; it is the sum of classes D and E divided by the sum of all classes and multiplied by 100.↵

*j*CO frequency was calculated on the basis of the assumption that class C contains disomes with the nonparental configuration of markers (*i.e*., like class C) and that the frequency of these disomes relative to those with the parental configuration (*i.e*., like class B) is the same as it is among mating-competent disomes. Thus, the CO frequency was calculated as the sum of classes D and E plus 0.59 × class C divided by the sum of all classes and multiplied by 100.