TABLE 2

Nonautonomous expression of suo mutations in ascospores

Homozygous crossesHeterozygous crosses
MutationsPigmentationGermination (%)PigmentationGermination (%)
suo1-11Green0Green25
suo2-9Green50Green50
suo3-1Green0Black100
suo4-39Green0Green12
  • Mutant ascospores, issued from either homozygous or heterozygous crosses involving the suo4-30, suo4-32, suo5-17, suo6-11, suo6-20 mutations, are black and show a 100% germination rate. The suo4-39 is a leaky mutant that produces few ascospores in homozygous crosses. The suo4 mutations leading to a complete sporulation deficiency when homozygous in a cross (Table 1) can be tested only in heterozygous crosses: The green (mutant) ascospores germinate in the range of 10% as shown above for the suo4-39 mutant. A total inability to germinate (0%) was ascertained on the following numbers of ascospores: 400 (suo1), 60 (suo3), and 75 (suo4).